SIGNALMENT: 4 year old, male neutered, Havanese, canine.
SOURCE/HISTORY: Biopsy of the colon. Diffuse thickening of the colon with barely any lumen left.
Colon: Markedly expanding the deep submucosa and extending into the underlying muscle is a marked multifocal to coalescing inflammatory infiltrate consisting of epithelioid macrophages, multinucleated giant cells, neutrophils, lymphocytes, and plasma cells. Small numbers of eosinophils are occasionally admixed. There is a marked regionally extensive area of necrosis. In these areas, the normal architecture is replaced by cellular debris and radiating eosinophilic material. The mucosal surface is multifocally ulcerated. Areas of fibroplasia extend into the serosal adipose tissue.
Colon: Marked, regionally extensive granulomatous colitis with necrosis and intralesional fungal hyphae Margins: Extends to margins of portions submitted
The changes within the sections examined were inflammatory in nature and an infectious etiology was suspected. Fungal hyphae were detected within the sections examined with PAS and GMS stains. Based on the anatomic location and morphology of the organisms, Pythium spp. was the top differential. Pythium PCR on the submitted tissue was positive for Pythium spp., confirming the histologic suspicion.
PATHOLOGIST: Catherine Lamm, DVM, MRCVS
Diplomate, American College of Veterinary Pathologists