HTL Histopathology & Diagnostic Techniques 3 — Questions and Answers
Question 1: Which fixative is considered the gold standard for routine surgical pathology and immunohistochemistry?
- 10% neutral buffered formalin (Correct answer)
- Bouin's solution
- Zenker's fixative
- Carnoy's fixative
Correct answer: 10% neutral buffered formalin
10% neutral buffered formalin (NBF) provides excellent morphological preservation and antigen retention, making it the standard fixative for most IHC applications.
Question 2: Frozen section diagnosis is most limited by which artifact?
- Ice crystal artifact distorting cellular detail (Correct answer)
- Over-staining of nuclei
- Loss of antigenicity
- Excessive tissue hardening
Correct answer: Ice crystal artifact distorting cellular detail
Ice crystals form during freezing and cause vacuolization and disruption of cellular architecture, limiting cytological detail in frozen sections.
Question 3: A gastric biopsy shows replacement of normal gastric mucosa by intestinal-type epithelium with goblet cells. This change is called:
- Intestinal metaplasia (Correct answer)
- Pseudopyloric metaplasia
- Dysplasia
- Hyperplasia
Correct answer: Intestinal metaplasia
Intestinal metaplasia is the replacement of gastric epithelium by intestinal-type epithelium, including goblet cells, and is a risk factor for gastric adenocarcinoma.
Question 4: In electron microscopy, which ultrastructural feature is pathognomonic for melanoma?
- Premelanosomes (melanosomes at various stages) (Correct answer)
- Weibel-Palade bodies
- Birbeck granules
- Dense-core neurosecretory granules
Correct answer: Premelanosomes (melanosomes at various stages)
Premelanosomes — melanosomes at stages I–IV of development — are the definitive ultrastructural marker of melanocytic differentiation in melanoma.
Question 5: The HER2/neu gene amplification status in breast carcinoma is most accurately assessed by which technique on tissue sections?
- Fluorescence in situ hybridization (FISH) (Correct answer)
- Routine H&E morphology
- PAS stain
- Giemsa stain
Correct answer: Fluorescence in situ hybridization (FISH)
FISH directly visualizes gene copy number at the chromosomal level and is the gold-standard method for confirming HER2 amplification when IHC is equivocal.
Question 6: Which staining method is preferred to demonstrate basement membrane thickening in diabetic nephropathy?
- Jones methenamine silver (JMS) stain (Correct answer)
- Hematoxylin and eosin
- Alcian blue
- Ziehl-Neelsen
Correct answer: Jones methenamine silver (JMS) stain
Jones methenamine silver stain highlights basement membranes black, making it ideal for demonstrating basement membrane thickening and the Kimmelstiel-Wilson nodules of diabetic nephropathy.
Question 7: A skin biopsy shows epidermotropism of atypical lymphoid cells with hyperconvoluted (cerebriform) nuclei. What diagnosis does this suggest?
- Mycosis fungoides (Correct answer)
- Seborrheic keratosis
- Psoriasis
- Lichen planus
Correct answer: Mycosis fungoides
Mycosis fungoides is a cutaneous T-cell lymphoma characterized by epidermotropic atypical lymphocytes with cerebriform nuclei, often forming Pautrier microabscesses.
HTL Histopathology & Diagnostic Techniques 3
Which fixative is considered the gold standard for routine surgical pathology and immunohistochemistry?