Free ASCP HT Practice Test: 60 Questions With Explanations

B. Adding to protein side chains, especially lysine, and forming methylene cross-links Formaldehyde is a non-coagulant, additive fixative. It binds basic amino acid side chains (lysine in particular) and peptide nitrogens, and where two binding sites sit close together it forms methylene bridges that cross-link proteins. It penetrates fast but cross-links slowly, which is why under-fixation is a common NBF mistake.

Why not the others: A describes alcohol fixatives. C confuses NBF with Bouin's fluid (picric acid is a coagulant). D describes EDTA decalcification, not fixation.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Fixation: Formaldehyde, pp. 142-143.

C. Differentiation in dilute acid alcohol after the hematoxylin Full-strength Harris is a regressive hematoxylin: it overstains on purpose, and the excess is pulled out of cytoplasm and chromatin by differentiation in dilute acid (for example, 0.5% HCl in 70% ethanol). Skip that step and leftover hematoxylin hides nuclear detail and can block eosin uptake entirely.

Why not the others: Bluing (A) turns hematoxylin from red to blue; it doesn't remove excess dye. A longer eosin step (B) can't use binding sites the hematoxylin already occupies. Dehydration (D) doesn't remove aluminum-hematein.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 13, Table 1 and Table 3; Ch. 20, Table 1 (progressive vs. regressive).

A. The cores were not embedded flat in the same plane Multiple small biopsies in one cassette should lie flat in the same plane so every piece is represented at the same depth. Cores that tilt or sit at different levels force deep trimming, which wastes scarce diagnostic tissue.

Why not the others: Section thickness (B) and water-bath temperature (C) don't change which cores appear at a given depth. Over-fixation (D) affects staining, not where the cores sit in the block.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II A.iv, Tissue Submission, pp. 29–30.

D. 70% ethanol or lower NBF contains phosphate buffer salts. Moving tissue straight into high-concentration alcohol precipitates those phosphates, so the first alcohol after NBF should be 70% or less. Tissue fixed in alcoholic formalin can start at 95% because it has already been in alcohol.

Why not the others: A, B, and C are all high-concentration alcohols that cause exactly the phosphate precipitation the question warns about.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II D.ii.i, Reagents for dehydration, p. 38.

C. Hydrochloric acid and potassium ferrocyanide Dilute HCl releases ferric ions from their binding proteins. The freed ferric ions react with potassium ferrocyanide to form insoluble ferric ferrocyanide, which is Prussian blue. Hemosiderin shows up as coarse blue granules; ferritin, if seen, is a faint blue blush.

Why not the others: A is von Kossa (calcium salt deposits). B is PAS (carbohydrates). D is the rhodanine method for copper.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 12, Iron Stain, p. 109.

A. Alcoholic picric acid This is formalin pigment (acid formaldehyde hematin). It forms when acidic formalin acts on hemoglobin, so it appears in blood-rich tissue. Neutral buffered formalin prevents it; alcoholic picric acid or alkaline alcohol removes it. Its birefringence helps identify it under crossed polarizers.

Why not the others: B removes mercury pigment left by mercuric chloride fixatives. C differentiates hematoxylin. D blues hematoxylin.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 21, "What is formalin pigment?", p. 190.

C. The exposure is at or above the action level but below the PEL and STEL, so monitoring must be repeated at least every 6 months and medical surveillance is required OSHA's formaldehyde limits are an action level of 0.5 ppm (8-hour TWA), a PEL of 0.75 ppm (8-hour TWA), and a STEL of 2 ppm (15 minutes). At 0.6 ppm the worker is at or above the action level but under the PEL, and 1.4 ppm is under the 2 ppm STEL. At or above the action level, the employer must repeat monitoring at least every 6 months and institute medical surveillance.

Why not the others: 0.6 ppm is below the 0.75 ppm PEL (A). 1.4 ppm is below the 2 ppm STEL (B). 0.6 ppm is above the 0.5 ppm action level (D).

Source: OSHA 29 CFR 1910.1048, Formaldehyde, (b) action level; (c)(1)-(2) PEL and STEL; (d)(3)(ii) periodic monitoring; (l)(1)(i) medical surveillance.

B. Apple-green birefringence Amyloid stains pink to salmon with Congo red in ordinary light and shows the characteristic apple-green birefringence under polarized light, which is the preferred way to read the stain. The long, linear dye molecule lines up along amyloid's beta-pleated sheet structure.

Why not the others: A is not how Congo red is read. C describes silver impregnation. D describes metachromatic dyes such as toluidine blue.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 1, Fig. 17; Ch. 18, Congo red; Ch. 22, nerve biopsy.

A. 2 µm Kidney biopsies are cut thin, about 2 µm (CAP/NSH guidance lists 1 to 3 µm), so glomerular basement membranes and cellularity aren't hidden by overlapping cells.

Why not the others: 5 µm (B) is routine paraffin thickness. 8 and 12 µm (C, D) fall in the range used for amyloid and would blur glomerular detail.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II F, Microtomy thickness table, p. 42; Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Embedding and Microtomy, p. 150.

B. EDTA (a chelating agent) at about pH 7-8 When nuclear DNA needs to be preserved, a chelating agent such as disodium EDTA (pH adjusted to about 7 to 8) is preferred. The trade-off is time: EDTA takes weeks rather than days.

Why not the others: Acids (A, C) work faster but can extract RNA and damage DNA, especially with overexposure. Formalin (D) fixes tissue; it doesn't remove calcium.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Decalcification, p. 146.

A. The globules are not glycogen; they are diastase-resistant PAS-positive material Diastase (alpha-amylase) digests glycogen. Since the control proves digestion worked, anything still PAS-positive is something else. In liver, a classic example is alpha-1 antitrypsin globules.

Why not the others: The negative control rules out failed digestion (B). Deteriorated Schiff reagent (C) or a skipped periodic acid step (D) would weaken or remove staining overall, not leave sharp positive globules.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 12, PAS Stain With and Without Enzyme Digestion, p. 113.

C. 150–200 mL At a 15–20:1 fixative-to-tissue ratio, a 10 mL specimen needs about 150–200 mL of total fixative. This recommendation applies to the CAP/NSH guidance for adding fixative when the amount present is inadequate; elsewhere the same guide also says collection procedures should specify at least 10 times the specimen volume for 10% NBF.

Why not the others: A is only 1–2:1, B is 5:1, and D tops out at 10:1. None reaches the 15–20:1 range stated in the scenario.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part I G.ii.b, Delayed time to Gross Examination — Addition of fixative to specimen(s), p. 23.

A. Iron hematoxylin resists decolorization by the acidic dye solutions that follow Trichrome dye solutions are acidic (roughly pH 1.5 to 3.0) and would strip an aluminum-based hematoxylin from nuclei. Iron hematoxylins hold up, leaving black nuclei for contrast against red muscle and blue or green collagen.

Why not the others: Collagen color comes from aniline blue or light green (B). Iron is the mordant in an iron hematoxylin (C). Red cytoplasm comes from the red plasma dye, such as Biebrich scarlet (D).

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 10, Entities: Nuclei; Factors That Affect Trichrome Staining: pH, pp. 93-96.

D. Silver attracted to the slide coating In some silver impregnation methods, silver is attracted to adhesive or charged slide coatings and deposits across the background. Use clean, uncoated slides for these stains.

Why not the others: A deposit on bare glass points to the slide, not the tissue, which rules out A, B, and C.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Embedding and Microtomy, Fig. 3, p. 150.

B. 368 mL Use C1V1 = C2V2: 95% x V1 = 70% x 500 mL, so V1 = 35,000 / 95 = 368.4 mL. Bring the volume to 500 mL with water.

Why not the others: 350 mL (C) treats the stock as if it were 100% alcohol. 332 mL (A) and 475 mL (D) come from setting up the ratio incorrectly.

Calculation: V1 = (C2 x V2) / C1 = (70 x 500) / 95 = 368.42 mL; rounded 368 mL

Source: ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Laboratory Operations B.2, Percent solutions/dilutions, p. 4.

D. Cryptococcus neoformans Mucicarmine stains the polysaccharide capsule of Cryptococcus, which helps separate it from other yeasts.

Why not the others: Mycobacteria (A) are shown with acid-fast stains. H. pylori (B) is usually shown with Giemsa, silver stains, or similar methods. Spirochetes such as Treponema (C) need silver methods such as Steiner or Warthin-Starry.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 1, Table 2 (Mayer's Mucicarmine Stain); Ch. 22, Infectious disease.

C. Michel medium Michel medium is a transport medium designed to preserve tissue-bound immunoglobulins in skin and kidney biopsies headed for immunofluorescence, and it is on the current HT list of fixatives and transport media. Follow the receiving lab's instructions; some ask for fresh tissue delivered promptly instead.

Why not the others: Formalin (A), Bouin's (B), and Carnoy's (D) are fixatives intended for paraffin processing, not the standard choice for direct immunofluorescence transport.

Source: ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Summary of Fixatives/Transport Media, p. 5; CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part I E.iii, specialized biopsies (renal/skin immunofluorescence); Part II C.i.c, non-formalin fixatives (Michel reference).

D. Frozen (cryostat) sections, mounted in an aqueous medium The alcohols and clearing agents used in paraffin processing dissolve neutral fat, so Oil Red O is done on frozen sections and mounted in a medium that won't dissolve the stained lipid.

Why not the others: A, B, and C all send the tissue through paraffin processing, which removes the very lipid being looked for.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 12, Oil Red O Stain, p. 113.

B. Inadequate bluing (too brief, an exhausted bath, or acidic water) Aluminum-hematein stays red until bluing converts it to an insoluble blue form. Bluing that's too brief, an exhausted bluing bath, or acidic tap water leaves nuclei purplish. Blue longer, change the bluing solution daily, or use Scott's tap water substitute.

Why not the others: Over-differentiation (A) makes nuclei pale, not red. Strong eosin (C) affects cytoplasm. Thick sections (D) look darker overall, not red.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 13, Fig. 5; Ch. 20, Table 3 ("Wrong color: purple").

C. 8-10 µm Thicker sections make Congo red-stained amyloid and its birefringence easier to see. CAP/NSH guidance lists 6 to 12 µm and the Dako guide cites 8 to 12 µm, so 8 to 10 µm fits both.

Why not the others: 2 µm (A) is renal-biopsy thickness. 4 µm (B) is routine and can under-show small deposits. 20 µm (D) is far thicker than either source recommends.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II F, Microtomy thickness table, p. 42; Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Embedding and Microtomy, p. 150.

D. Treat with iodine, then sodium thiosulfate Mercury pigment forms throughout tissue fixed in mercuric chloride mixtures and must be removed with iodine followed by sodium thiosulfate. A related point: mercury fixatives dissolve hemosiderin, so they're a poor choice when an iron stain is needed.

Why not the others: Alcoholic picric acid (A) removes formalin pigment. B and C are hematoxylin steps, not pigment removal.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Mercuric Chloride, p. 145; Ch. 21, B5 questions, p. 191.

B. Sulfated mucin is present At pH 2.5, Alcian blue stains both carboxylated and sulfated acidic mucins. At pH 1.0, only sulfated groups stay ionized enough to bind the dye, so staining at pH 1.0 means sulfated mucin.

Why not the others: Neutral mucin (A) and glycogen (D) are Alcian blue-negative and PAS-positive. Carboxylated-only mucin (C) would stain at pH 2.5 but not at pH 1.0.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 1, Table 2 (Alcian Blue); Ch. 23, Alcian Blue.

A. Class B (for example, CO2 or a multipurpose ABC dry chemical) OSHA defines a Class B fire as one involving flammable or combustible liquids, flammable gases, greases, and similar materials, which covers xylene and alcohols. Multipurpose dry chemical is approved for Class A, B, and C fires.

Why not the others: Class A (B) is for ordinary combustibles such as paper and wood. Class D (C) is for combustible metals. Class K (D) is for commercial cooking oils and fats.

Source: OSHA 29 CFR 1910.155, Fire protection definitions, (c)(8)-(11) fire class definitions; (c)(32) multipurpose dry chemical.

B. To replace the dehydrating alcohol with a solvent that mixes with both alcohol and paraffin Water and paraffin don't mix, so tissue is dehydrated in alcohol first. A clearing agent that mixes with both alcohol and paraffin then replaces the alcohol so molten paraffin can infiltrate. The sequence is dehydration, clearing, infiltration.

Why not the others: Formalin removal (A) happens through washing and dehydration. Calcium removal (C) is decalcification. Hardening (D) comes from fixation and paraffin infiltration.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Tissue Processing, p. 148.

A. Hall's bile stain Hall's method demonstrates bile pigment (bilirubin), and it's on the HT stain list that applies from November 1, 2026. A negative Perls' rules out hemosiderin.

Why not the others: Fontana-Masson (B) shows melanin and other argentaffin substances. Rhodanine (C) shows copper. von Kossa (D) shows calcium salt deposits.

Source: ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Summary of Stains, p. 5; Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 1, Table 2 (Hall's Stain); Ch. 12.

A. Dry slides in an oven set just above the paraffin's melting point (commonly 58-60 °C) for an adequate time CAP/NSH guidance: air-dry, then oven-dry just above the paraffin's melting point, commonly 58 to 60 °C for 15 to 30 minutes, with longer drying for some special techniques. Removing the water layer and melting the wax improves adhesion.

Why not the others: B, C, and D all leave water trapped between the section and the glass, a common reason sections lift.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II F.iv.b, Slide Drying; Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Embedding and Microtomy, p. 150.

D. 4 hours For breast specimens tested for ER/PR and HER2, the recommendation is at least 6 hours and 6 to 72 hours total in 10% NBF. Four hours is under-fixation.

Why not the others: 8, 24, and 70 hours (A, B, C) all fall inside 6 to 72 hours.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part I D.iv.e, Fixation time for breast tissue specimens.

C. Fite M. leprae cell walls are easily damaged during deparaffinization and by strong acid decolorizers. The Fite method adds peanut oil to the deparaffinizing solvent and uses a weaker acid, which preserves the organisms.

Why not the others: Standard Ziehl-Neelsen (A) can lose M. leprae. The Gram stain (B) is aqueous and doesn't penetrate lipid-rich mycobacterial walls. GMS (D) is a fungal stain.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 11, Carbol Fuchsin Acid-Alcohol Stain: Modifications, p. 103; Ch. 23, Acid-Fast Stain.

C. Prolonged acid exposure damaging nucleic acids Overexposure to acid decalcifiers extracts RNA and strips bases from DNA, leaving hematoxylin less to bind, so nuclei look pale and smudgy. Decalcification should be monitored to its endpoint and the acid washed out afterward.

Why not the others: Concentrated hematoxylin (B) and thick sections (D) make nuclei darker, not paler. Under-fixation (A) can blur detail, but the scenario points straight at the acid exposure.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Decalcification, p. 146; Ch. 15, Bone, p. 139.

D. Elastic fibers black; collagen red; other tissue yellow Verhoeff's iron hematoxylin stains elastic fibers (and nuclei) black. Van Gieson's picro-fuchsin then stains collagen red and other tissue yellow.

Why not the others: A reverses the colors. B resembles trichrome results. C matches neither component.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 1, Table 2 (Verhoeff/Van Gieson) and Fig. 15a.

C. Use a documented decontamination procedure at defined intervals and keep records of the decontamination CAP/NSH guidance calls for a documented procedure for routine cryostat decontamination at defined intervals, with the decontamination documented and records available for examination. The current HT guideline also includes infection control, including disinfection and decontamination, within Laboratory Operations.

Why not the others: Xylene (A) is a solvent, not the required decontamination policy. Freezing does not eliminate the need for decontamination (B). Defrosting alone (D) is not a documented disinfection procedure.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part I H.ii, Cryostat decontamination, p. 25; ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Laboratory Operations A.4, Infection control, p. 4.

B. Buffered glutaraldehyde The EM portion of muscle and nerve biopsies is fixed in buffered glutaraldehyde and post-fixed in osmium tetroxide, usually by an EM specialist. Glutaraldehyde is on the current HT fixatives list.

Why not the others: NBF (A), Bouin's (C), and alcohol (D) are light-microscopy fixatives and don't preserve ultrastructure as well.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Frozen Sections, p. 148; ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Summary of Fixatives/Transport Media, p. 5.

B. 0.1% Eyewash facilities are required in the immediate work area if eyes could be splashed with solutions containing 0.1% or more formaldehyde. Quick-drench showers are required where skin could be splashed with solutions of 1% or more.

Why not the others: 1% (A) is the skin-splash shower threshold. 10% and 37% (C, D) are far above the eyewash trigger.

Source: OSHA 29 CFR 1910.1048, Formaldehyde, (i)(2) quick drench showers; (i)(3) eyewash facilities.

D. Too few, or dye-laden, alcohol rinses after the eosin Good eosin gives at least three tones: deep pink muscle and cytoplasm, lighter pink collagen, and orange-red red cells. Intense, undifferentiated eosin usually means the post-eosin alcohol rinses aren't removing excess dye, either because there are too few dips or because the rinses have become dilute eosin themselves.

Why not the others: Hematoxylin problems (A, B) don't produce excess pink. Exhausted eosin (C) causes pale staining, not intense staining.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II G.i, H&E quality criteria; Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 20, Table 4 (eosin troubleshooting); Ch. 13, notes on rinses.

B. Processing time was too short for fatty tissue, leaving incomplete dehydration, clearing, and infiltration Fatty specimens need longer fixation and processing than small biopsies. A schedule tuned for biopsies can leave fatty tissue incompletely processed and poorly infiltrated.

Why not the others: Over-fixation (A) makes tissue firmer, not softer. Paraffin temperature (C) wouldn't single out one tissue type. Section thickness (D) comes after the problem has already happened.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Tissue Processing, pp. 148-149; CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II C.ii.b, Fixation by tissue type.

C. Fontana-Masson In Fontana-Masson, melanin (and some amines) reduces an alkaline silver diammine solution directly. That's an argentaffin reaction. A melanin bleach can confirm the pigment.

Why not the others: Reticulin (A), Grimelius (B), and Warthin-Starry (D) are argyrophil methods: they need a separate reducing or developing step to make the silver visible.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 19, "What is the difference between argentaffin and argyrophilic reactions?", pp. 167-168; Ch. 11, Silver Stains.

B. Label slides only as needed, and match slides to their blocks before they leave the lab CAP/NSH guidance calls it good practice to label slides only as required and to avoid pre-labeling large numbers in advance. Slides should be matched against their blocks before delivery. Each slide needs the accession number, block identifier, level, patient name, and stain identifier.

Why not the others: Large batches of pre-labeled slides (A) invite mix-ups. Labeling after staining (C) breaks the link between the section and its block during the run. An accession number alone (D) leaves out required identifiers.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II F.iv.a, Slides — Labelling, p. 43.

A. Mordanting the sections in Bouin's fluid NBF isn't the ideal fixative for trichromes. Post-fixing (mordanting) paraffin sections in a picric acid solution such as Bouin's boosts the intensity and brilliance of trichrome staining.

Why not the others: B targets formalin pigment, not trichrome intensity. C removes mercury pigment. D is a decalcifier.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 10, Factors That Affect Trichrome Staining: Fixation, p. 96; Ch. 16, Bouin's Fluid, p. 144.

D. To tone the silver, turning fibers from brown to black After oxidation, sensitization, silver impregnation, and reduction (development in formalin), gold chloride replaces the silver with metallic gold. This toning step turns reticulin fibers from brown to black.

Why not the others: Oxidation (A) uses an oxidizer such as permanganate. Sensitization (B) uses a metal salt. Reduction (C) is the formalin development step.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 12, Reticulin Stain: Principles of Staining, p. 109.

B. 29.2 g Grams = molarity x molecular weight x liters = 0.5 x 58.44 x 1 = 29.22 g.

Why not the others: 58.4 g (A) makes a 1 M solution. 11.7 g (C) makes 0.2 M. 5.8 g (D) makes 0.1 M.

Calculation: g = M x MW x L = 0.5 x 58.44 x 1 = 29.22 g

Source: ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Laboratory Operations B.3, Molar solutions, p. 4.

A. Centrifuge it, fix the pellet, and process it as a cell block A cell block is made from the centrifuged pellet, fixed, embedded in paraffin, sectioned, and stained. It sometimes shows cells that weren't on the smears. Cell blocks are named under Processing in the content guideline.

Why not the others: Fluid can't be frozen-sectioned directly (B). Decalcification (C) is irrelevant. An air-dried spread (D) is a smear, not a block you can section.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 13, Appendix, p. 128; ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Processing B.8, Cytologic specimens (e.g., cell blocks), p. 2.

D. The phosphate or carbonate anions of calcium salts In von Kossa, silver displaces calcium from calcium phosphate or carbonate deposits, forming silver salts that light reduces to black metallic silver. So it marks the anion, not the calcium itself. Alizarin red S, by contrast, binds calcium.

Why not the others: Calcium itself (A) is shown by alizarin red S. Iron (B) is Perls'. Copper (C) is rhodanine.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 19, argentaffin/argyrophil discussion (von Kossa), p. 167; Ch. 18, Alizarin red S, p. 165.

B. Add an adhesive such as gelatin to the water bath Water-bath adhesives such as gelatin (or adhesive slides) improve section attachment. Skip adhesive coatings for some silver stains, which deposit silver on them.

Why not the others: Xylene (A) doesn't mix with water. Alcohol (C) won't flatten paraffin ribbons properly. Boiling (D) melts and distorts sections.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II F.ii, water-bath additives; ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Embedding/Microtomy B.3, Gelatin/adhesive, p. 3.

A. 3-4 mm Thickness controls how well reagents penetrate. CAP/NSH guidance recommends gross sections no thicker than 3 to 4 mm that fit easily between the top and bottom of the cassette. In 10% NBF, a 4 mm section reaches complete fixation in about 24 hours.

Why not the others: 1 cm (B) and 6-8 mm (C) are too thick for even fixation and processing. D is false; overly thick tissue under-fixes in the center no matter how long it sits.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II A.iv, Tissue Submission, p. 29; Part II C.ii.c, Tissue Size, p. 34.

A. Fungal walls black on a green background GMS deposits silver on the polysaccharides in fungal cell walls, so fungi appear black or gray-black against a light green counterstain.

Why not the others: Magenta (B) describes PAS. Red on blue (C) describes acid-fast stains. Apple-green birefringence (D) describes Congo red-stained amyloid.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 1, Table 2 and Fig. 6; Ch. 22, Fig. 5.

C. Water carried forward from exhausted alcohols, preventing proper clearing and paraffin infiltration Water and paraffin don't mix. When dehydrating alcohols are diluted by carryover, water reaches the clearing agent and paraffin, and the center of the tissue never infiltrates. Reagent rotation should be scheduled by workload, such as the number of cassettes or runs processed.

Why not the others: Embedding temperature (A) doesn't leave unprocessed centers. Over-fixation (B) firms tissue. A dull blade (D) causes cutting artifacts, not soft, unprocessed tissue.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Tissue Processing, p. 148; CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II D, processor maintenance and reagent rotation.

C. Don't use it as is: lost sulfur dioxide has regenerated basic fuchsin, which can cause false-positive staining Schiff reagent turns pink when it loses SO2, which regenerates some basic fuchsin. That free dye can bind polyanions such as cartilage matrix and mast cell granules and give false positives, so the reagent is unfit until it's regenerated with a sulfurous acid source or replaced, per lab policy.

Why not the others: A and B ignore the false-positive risk. Periodic acid (D) is the oxidizing step done on the slide, not a fix for the reagent.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 19, "How does pH influence the staining mechanism of Schiff's reagent?", p. 170.

D. Temperature of the embedding paraffin CAP/NSH guidance calls for daily monitoring of the embedding paraffin's temperature, along with set temperatures for the holding paraffin, the work surface, and the forceps.

Why not the others: Blade angle (A) and water-bath additives (B) belong to microtomy, not the embedding center. Mold cleaning (C) is a procedure item, not the daily temperature check.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II E.i, Embedding center operation, p. 41.

C. Absolute or 95% ethanol Sodium urate crystals dissolve in water, so aqueous fixatives, NBF included, can wash them out. Specimens from patients with gout are usually fixed in alcohol.

Why not the others: NBF (A), Bouin's (B), and Zenker's (D) are all aqueous fixatives.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Alcoholic Fixatives (p. 145) and Table 1, Urate Crystals (p. 146).

C. Hold the specimen and follow the lab's written label-discrepancy and rejection procedure, contacting the submitting source At least two patient-specific identifiers must match between the container and the requisition. Mismatches follow the lab's documented correction and rejection policy. In some cases only the originator may make labeling changes, and irreplaceable specimens have a defined correction pathway.

Why not the others: Fixing it yourself (A) bypasses the policy. One identifier (B) isn't enough. Discarding (D) can destroy a specimen that can't be replaced.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part I A-B, Patient Identification and Proper Labeling; Part I E.ii.e, Quality Assurance Monitors.

C. Lower the pH of the hematoxylin solution Epithelial mucin should be clear on a good H&E. Blue mucin usually means the hematoxylin's pH is too high, and that hematoxylin often overstains nuclei too. Lowering the hematoxylin pH should remove the mucin staining.

Why not the others: Longer bluing (A) changes color, not where the hematoxylin binds. Stronger eosin (B) doesn't remove blue from mucin. Thinner sections (D) lighten everything without fixing the cause.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 15, Gastrointestinal Tract and Fig. 2, p. 137.

A. Carnoy's fluid Carnoy's fluid is ethanol, chloroform, and acetic acid (60:30:10). It contains no water, fixes by coagulating proteins and chromatin, and nearly dehydrates the tissue, so paraffin processing can be shorter than after NBF.

Why not the others: NBF (B) and zinc formalin (C) are aqueous, formaldehyde-based fixatives. Glutaraldehyde (D) is an aldehyde cross-linker used mainly for electron microscopy.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Alcoholic Fixatives (p. 145) and Zinc salts (p. 145); ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Summary of Fixatives/Transport Media, p. 5.

D. 2-3 µm The CAP/NSH thickness table lists 2 to 3 µm for bone marrow, thinner than routine tissue, so densely packed marrow cells can be told apart.

Why not the others: 4-5 µm (C) is the routine paraffin range. 6-8 µm (B) and 8-10 µm (A) fall in the thicker ranges used for amyloid or nerve histochemistry.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II F, Microtomy thickness table, p. 42.

B. EA The Pap stain is essentially an H&E with extra dyes: OG-6 (orange G) as the first counterstain, then EA, which contains light green SF yellowish and eosin Y. Bismarck brown, a traditional EA dye, is usually left out today because phosphotungstic acid precipitates it.

Why not the others: OG-6 (A) is the orange G counterstain. Harris hematoxylin (C) is the nuclear stain. Scott's (D) is a bluing solution.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 13, Appendix, p. 129; ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Staining B.13, Cytologic stains, p. 3.

C. Speeds removal of the clearing agent, making wax infiltration more efficient A vacuum-assisted processor improves the efficiency of wax infiltration by speeding the removal of the clearing agent from the tissue.

Why not the others: Vacuum doesn't fix tissue (A), remove calcium (B), or remove pigment (D).

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Tissue Processing, p. 148.

D. A human-readable identifier (accession, specimen, and block) Barcodes must not be the only identifying mark; a human-readable identifier is also required. At minimum, the unique cassette identifier includes the accession case identifier, the specimen identifier, and the block identifier, and it must stay legible through processing.

Why not the others: Date of birth (A) and the pathologist's name (C) aren't part of the minimum cassette identifier. B is exactly what the guidance rules out.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II B, Tissue Cassette Identification, p. 30; ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Laboratory Operations F.1, Quality assurance, p. 4.

A. To produce a visible colored product where the antibody-antigen reaction is detected IHC finds a specific antigen with an antibody. The reaction is labeled by a detection system and made visible by a chromogen, such as DAB, which leaves a colored deposit at the site. For HT, IHC is tested at the level of terms like this plus fixation and processing; detection theory and antigen retrieval are HTL-only.

Why not the others: Fixation (B) happens before staining. Unmasking antigens (C) is antigen retrieval. A nuclear counterstain (D) is a separate dye, such as hematoxylin.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II G.iii, Immunohistochemical stains (definition and DAB detection); ASCP BOC HT/HTL Examination Content Guideline (testing dates beginning Nov 1, 2026; revised July 10, 2026), Staining B.11.a, IHC terminology/definitions, p. 3.

B. Standardize the block-holder (chuck) position on all microtomes CAP/NSH guidance says to standardize the position of the microtome chuck on every microtome so blocks can be recut on any of them without re-facing and losing tissue.

Why not the others: Deeper trimming (A) is the tissue loss you're trying to avoid. Thickness (C) doesn't fix the angle. Re-embedding (D) is unnecessary and risky.

Source: CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II F.ii.a, Block trimming.

C. Modify antigenic sites and weaken immunostaining Formaldehyde adds chemically to proteins, and that can modify antigenic sites and suppress immunostaining. That's one reason labs set fixation-time ranges, such as 6 to 72 hours in 10% NBF.

Why not the others: A is backward. B is false; formaldehyde binds protein side chains. D describes decalcification.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 16, Fixation, p. 141; CAP/NSH Practical Guide to Specimen Handling in Surgical Pathology, v12.0 (Mar 2025), Part II C.ii.a, Fixation times (6-72 h).

D. Their thick peptidoglycan walls retain the crystal violet-iodine Crystal violet stains everything, and iodine helps it stick to gram-positive walls, which are rich in peptidoglycan. The acetone-alcohol decolorizer washes the dye out of gram-negative bacteria, which have thin peptidoglycan and a lipid outer membrane; the counterstain then colors them pink.

Why not the others: Mycolic acid (A) explains acid-fast staining. Gram-negative bacteria, not gram-positive, take the red counterstain (B). Silver (C) belongs to other methods, such as Warthin-Starry.

Source: Dako/Agilent Education Guide: Special Stains and H&E, 2nd ed. (2010), Ch. 11, Gram Stain: Principles of Staining, p. 99; Ch. 23, Brown and Brenn Stain.