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Apocrine Gland Tumors of Anal Sac Origin |  |
| These have been definitively identified only in dogs, although anecdotal reports suggest they may also occur in cats. Older English Cocker and Springer Spaniels, Dachshunds, Alaskan Malamutes, German Shepherds, and mixed-breed dogs are most at risk. Unlike hepatoid gland tumors (see
Hepatoid Gland Tumors), there is no sex predilection. They most commonly appear as deep, firm, nodular masses near the anal sac. As these lesions grow, they may compress the rectum and induce constipation. Some of these tumors are associated with a paraneoplastic syndrome that is characterized by hypercalcemia and results in anorexia, weight loss, polyuria, and polydipsia. They are often highly infiltrative into the pelvic canal and commonly (90%) metastasize to the
sublumbar lymph nodes or to distant internal organs (40%). Wide surgical excision, including involved lymph nodes, is the treatment of choice. Even if the tumor cannot be totally resected, debulking can be of value in dogs with pseudohyperparathyroidism because the hypercalcemia is related to the total tumor mass. Adjunct chemotherapy and radiation therapy may also be of benefit, but few dogs live >1 yr after the tumor has been recognized. |
