| Tumors and tumor-like conditions of sebaceous glands are common in dogs, infrequent in cats, and rare in other domestic animals. Based on morphologic more than on behavioral features, 4 categories of benign sebaceous gland proliferations have been described. In humans, in which a roughly similar classification scheme is traditionally used, it has been proposed that all benign sebaceous gland tumors be called sebaceomas. |
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Sebaceous gland hamartomas are solitary lesions reported only in dogs. These lesions are distinguished from sebaceous gland hyperplasias and adenomas because they are linear or circumscribed, several centimeters in length or diameter, and are usually identified shortly after birth. |
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Sebaceous gland hyperplasias (senile sebaceous hyperplasias) represent a senile change in dogs and cats. In dogs, Manchester, Wheaten, and Welsh Terriers are at greatest risk. In cats, there is no breed predilection, but females develop these lesions more frequently than males. In both species, the head and abdomen are affected most commonly. Sebaceous hyperplasias commonly appear as papillated masses seldom >1 cm in diameter often with a shiny, keratotic surface. |
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Sebaceous gland adenomas are seen in all domestic animals but are so common in older dogs and cats, they can be considered primarily a small animal neoplasm. Coonhounds, English Cocker Spaniels, Cocker Spaniels, Huskies, Samoyeds, and Alaskan Malamutes are the canine breeds most likely to develop these tumors; Persians are the feline breed most predisposed. In dogs, these tumors frequently are clinically indistinguishable from sebaceous hyperplasias, but they tend to be
larger (typically >1 cm). They are often multiple and may occur anywhere on the body but are commonly found on the head. Sebaceous adenomas may be covered with a serocellular crust and exhibit pleocellular inflammation and superficial pyoderma.
Sebaceous gland epitheliomas are a variant of sebaceous adenoma distinguished by lobules composed primarily of basal progenitor cells rather than mature sebocytes. Because they often have irregular lobules that extend into the deep dermis, they can occasionally be confused with sebaceous carcinomas. These tumors are found in older dogs and rarely cats. They appear as ulcerated nodules that may be several centimeters in diameter. A papillated epidermal surface and
pigmentation are variable findings. |
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Sebaceous gland adenocarcinomas are rare in domestic animals. They are recognized almost exclusively in dogs and cats, generally in middle-aged or older animals. Cavalier King Charles Spaniels, Cocker Spaniels, and Scottish, Cairn, and West Highland White Terriers are most at risk. Male dogs and female cats may be predisposed. These lesions are often ulcerated and may be indistinguishable from sebaceous epitheliomas or other cutaneous carcinomas. They are locally
infiltrative and may metastasize to regional lymph nodes late in the disease. |
| Once a diagnosis is established, treatment is optional for benign sebaceous gland tumors unless they are secondarily inflamed and infected. For malignant adenocarcinomas, excision is the treatment of choice, but complete removal can be difficult due to the infiltrative nature of this tumor; adjunct radiotherapy may be required. Even benign sebaceous gland growths recur if remnants are left at the surgical site. In addition, animals that develop one sebaceous gland hyperplasia or
adenoma often develop new lesions at other sites over time. No established protocol of chemotherapy for any of these lesions has been defined. Oral retinoids may prevent recurrence of sebaceous hyperplasia, but their use remains poorly defined and consultation with a veterinary oncologist or dermatologist is strongly recommended. |
