Apocrine gland anal sac adenocarcinoma with perineural metastasis in a cat.

Case summary: A 15-year-old female spayed domestic shorthair cat was presented for hyporexia and acute development of L4-Cd myelopathy (urinary incontinence, pelvic limb paresis with hyporeflexia and absent tail tone). Humane euthanasia was elected owing to the rapid neurological deterioration and necropsy was performed. Post-mortem examination identified a right-sided anal sac mass and medial iliac lymphadenopathy. No gross lesions were evident in the cauda equina or peripheral nerves. Histopathology and immunohistochemistry utilizing wide-spectrum cytokeratin confirmed apocrine gland carcinoma of the anal sac with lymph node, peripheral nerve and cauda equina metastasis.

Relevance and novel information: This is the first report of feline anal sac adenocarcinoma metastasizing to perineural tissue. In addition, it provides a novel differential diagnosis for L4-Cd myelopathy and urinary incontinence in a cat.