Hepatoid Gland Tumors
(Perianal gland tumors, Circumanal gland tumors) |  |
| These common neoplasms arise from modified sebaceous glands that are most abundant in the cutaneous tissues around the anus but may also be present along the ventral midline from the perineum to the base of the skull, the dorsal and ventral tail, and in the skin of the lumbar and sacral regions. Because androgens stimulate the development of hepatoid glands, the incidence of proliferative lesions of hepatoid glands in intact, male dogs is 3 times that in females. |
| Benign hepatoid gland tumors are divided into
hepatoid gland hyperplasias and adenomas; however, as with benign sebaceous gland tumors, there is a continuum from hyperplasia to adenoma. Here, they will be considered as a single entity. Hepatoid gland adenomas are most common in aged dogs. Siberian Huskies, Samoyeds, Pekingese, and Cocker Spaniels are most commonly affected. Tumors may develop at any site where hepatoid glands are present, but 90% occur in the perianal
region. Grossly, they appear as one or (more commonly) multiple intradermal nodules 0.5-10 cm in diameter. Larger lesions commonly ulcerate, and hemorrhagic, keratinaceous material can often be extruded with local pressure. Large tumors can compress the anal canal and make defecation difficult. Up to 95% of male dogs respond completely to castration; in those that do not, the pituitary-adrenal axis should be evaluated and, if no abnormality is detected, the dog should be reevaluated
for the presence of a low-grade hepatoid gland adenocarcinoma. Excision may be used concurrently to remove extremely large or ulcerated tumors that have become secondarily infected. Surgery is the treatment of choice for females with hepatoid gland adenomas but may need to be repeated because recurrence is common. Radiation therapy is also an option and has a 2-yr cure rate of 69% for benign tumors. Cryosurgery is another therapeutic alternative, but because of the complication of
fecal incontinence, should be used only when tumors are not amenable to surgical intervention. Diethylstilbestrol has been used in the past as an alternative to castration, but because of severe side effects, including aplastic anemia and cystic prostatic hyperplasia, it should be used with extreme caution, if at all. |
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Hepatoid gland adenocarcinomas are uncommon canine neoplasms that generally appear as nodular lesions affecting the perianal region. These tumors are found in male dogs 10 times more commonly than in females. Siberian Huskies, Alaskan Malamutes, and Bulldogs are most likely to develop this tumor. Histologic evaluation is the best means of diagnosis; however, there is debate about how to distinguish low-grade malignant tumors from hepatoid adenomas because
well-differentiated forms can be confused with adenomas, and anaplastic forms can be confused with apocrine gland adenocarcinomas of anal sac origin. These tumors have metastatic potential and often spread to regional lymph nodes. Treatment consists of wide surgical excision including involved lymph nodes and, possibly, subsequent radiation. These tumors are generally not responsive to castration or to estrogen therapy, and it is unknown whether chemotherapy is of benefit for
metastatic disease. The prognosis is guarded. |
