Subcutis: Pyogranulomatous inflammation with intra-lesional foreign material

This was an aspirate from a foreign body reaction in a dog. Notice the marked variability in the macrophage morphology. Some macrophages are spindle shaped and some epithelioid and display phagocytosis. A ruptured squamous cyst was suspected.

A: Spindleoid clumped macrophages with a central plasma cell and peripheral neutrophils.

B: Refractile foreign material (presumed keratin).

C: Epithelioid macrophages displaying neutrophil phagocytosis.

D: Foreign body giant cell.

First published: Wed, Dec 1 2010