September 2019


Signalment (JPC 2031602):  A dog

HISTORY:  This large mass was located lateral to the anus.

HISTOPATHOLOGIC DESCRIPTION:  Anal sac:  Effacing subepithelial connective tissue, partially surrounding the anal sac, replacing normal anal sac apocrine glands, infiltrating and compressing adjacent skeletal muscle, and compressing adjacent moderately ectatic anal sac apocrine glands is an unencapsulated, multilobulated, infiltrative, densely cellular neoplasm composed of polygonal cells arranged in multiple patterns including formation of variably sized islands and tubuloacini (tubular type), solidly cellular areas, and multifocal rosette and pseudorosette formation, on a coarse  fibrovascular stroma. Neoplastic cells are cuboidal to columnar with variably distinct borders and moderate amounts of eosinophilic cytoplasm with rare apical blebbing. Nuclei are round to oval, located basally within tubuloacinar arrangements, and have finely stippled chromatin with 1-2 nucleoli. There is mild anisocytosis and anisokaryosis and the mitotic rate averages 2-3 per 40x high power field. Multifocally glandular lumina contain eosinophilic amorphous secretory product occasionally mixed with sloughed neoplastic cells and necrotic cellular debris. There is multifocal scattered single cell necrosis and hemosiderin-laden macrophages. Neoplastic cells are present within dilated lymphatic vessels. Neoplastic cells focally form a large single duct lined by multiple layers of columnar neoplastic cells that contains low numbers of erythrocytes, sloughed neoplastic cells, hemosiderin-laden macrophages, and fibrous connective tissue with necrotic cellular debris. Multifocally the periglandular and subepithelial connective tissue surrounding the neoplasm is infiltrated by moderate numbers of lymphocytes, plasma cells, and fewer eosinophils. Subjacent to the hyperpigmented and mildly hyperplastic anal sac epithelium are multifocal melanin-laden macrophages (pigmentary incontinence).

MORPHOLOGIC DIAGNOSIS:  Anal sac:  Adenocarcinoma of the apocrine glands of the anal sac, breed not specified, canine.

CONDITION:  Adenocarcinoma of the apocrine glands of the anal sac (also see D-N06)

SYNONYMS:  Adenocarcinoma of the apocrine glands of the anal sac (AAGAS)

                          Anal sac gland carcinoma (ASGC)

                          Carcinomas of the apocrine glands of the anal sac (CAGAS)

                          Anal sac apocrine gland adenocarcinoma (ASAGAC)








Microscopically – Perianal neoplasia:

Clinically – Hypercalcemia: HARDIONS-T



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