Pathology and Microbiology Flashcards

Which type of granuloma, characterized by central caseation necrosis, is pathognomonic of tuberculosis?

Answer: Caseating granuloma

Caseating granulomas with central cheesy necrosis surrounded by epithelioid histiocytes and Langhans giant cells are characteristic of Mycobacterium tuberculosis infection.

A decedent's liver shows a large abscess containing 'anchovy paste' material. Which organism is most likely responsible?

Answer: Entamoeba histolytica

E. histolytica produces hepatic abscesses with characteristic reddish-brown 'anchovy paste' or 'chocolate sauce' contents due to liquefied necrotic hepatocytes.

Which cell type predominates in a chronic inflammatory infiltrate observed histologically?

Answer: Lymphocytes and macrophages

Chronic inflammation is characterized by lymphocytes, macrophages, and plasma cells rather than the neutrophils seen in acute inflammation.

During embalming, the formaldehyde-based solution acts as a fixative primarily by:

Answer: Cross-linking proteins

Formaldehyde creates methylene bridge cross-links between amino groups of proteins, halting autolysis and microbial decomposition.

Which stain is used to identify acid-fast organisms such as Mycobacterium tuberculosis in tissue sections?

Answer: Ziehl-Neelsen stain

The Ziehl-Neelsen (carbol-fuchsin) stain highlights mycobacteria as bright red rods on a blue background due to their waxy cell walls.

A 45-year-old decedent has bilateral pleural effusions and ascites at autopsy. This pattern of fluid accumulation is best described as:

Answer: Anasarca

Anasarca is generalized edema involving body cavities and subcutaneous tissue, commonly resulting from heart failure, cirrhosis, or nephrotic syndrome.

Which hepatitis virus is transmitted exclusively via the parenteral route and has no vaccine available?

Answer: Hepatitis C

Hepatitis C is transmitted through blood/needles; unlike HBV, no approved vaccine exists, and it frequently leads to chronic liver disease.