Apocrine adenocarcinoma of the anal sacs is a malignant neoplasm arising from the apocrine glands. These tumors are common in dogs and relatively uncommon in cats. The tumors are usually unapparent to owners but are discovered by digital rectal palpation. Because the tumors are often occult, the majority will have already metastasized to regional lymph nodes at the time of diagnosis. Distant metastases may be found in the lungs, spleen, or liver. Larger masses may impinge on the rectum, resulting in straining to defecate. Paraneoplastic hypercalcemia occurs in approximately half of cases and is associated with a shorter survival time. Depending on the size and local invasiveness of the tumor, complete surgical resection or debulking is beneficial. Also, surgical removal of enlarged lymph nodes may increase survival time. Adjunct chemotherapy or radiation therapy may increase survival time but is not usually curative.
Links to sections in MVM:
Anal Sac Disease
Apocrine Gland Tumors of Anal Sac Origin
Hepatoid Gland Tumors
Hypercalcemia of Malignancy
References
Potanas CP, Padgett S, Gamblin RM. Surgical excision of anal sac apocrine gland adenocarcinomas with and without adjunctive chemotherapy in dogs: 42 cases (2005-2011). J Am Vet Med Assoc. 2015 Apr 15;266(8):877-884. doi: 10.2460/javma.246.8.877
Anderson CL, MacKay CS, Roberts GD, Fidel J. Comparison of abdominal ultrasound and magnetic resonance imaging for detection of abdominal lymphadenopathy in dogs with metastatic apocrine gland adenocarcinoma of the anal sac. Vet Comp Oncol. 2015 Jun 13(2):98-105. doi: 10.1111/vco.12022