General Considerations

•sebaceous gland tumors are subdivided into adenomatous hyperplasia, epithelioma, adenoma, or ADC according to the level of cellular maturation

•modified sebaceous glands include eyelid meibomian gland and perianal gland

•sebaceous gland tumors are rare in cats (2.3%-4.4%), but common in dogs (6.8%-7.9%)

Adenomatous Hyperplasia

•sebaceous hyperplasia can progress to sebaceous adenoma or ADC and may be a precursor to their development

•breed predisposition: Beagle, Cocker Spaniel, Poodle, and Miniature Schnauzer

•sex predisposition: males in cats and dogs

•androgen influence is suspected in pathophysiology and hyperadrenocorticism should be assessed in female dogs and dogs with recurrent adenomatous hyperplasia of the sweat glands

•gross appearance: solitary (± multiple) and grossly indistinguishable from adenoma

•sites: head in cats and limbs, trunk, and eyelids in dogs

•treatment: surgery

•prognosis: good with local tumor recurrence rare (1.1%) but de novo tumor development in up to 10%

Sebaceous Epithelioma

•breed predisposition: Shih Tzu, Lhasa Apso, Alaskan Malamute, Siberian Husky, and Irish Setter

•solitary form occurs primarily on the head and particularly the eyelids

•generalized form has been reported

•treatment: surgery

•prognosis: good with local tumor recurrence rate 6%

Sebaceous Gland Adenoma

•breed predisposition: Cocker Spaniel, Springer Spaniel, Boston Terrier, and Wire-Haired Terrier

•gross appearance and biologic behaviour similar to adenomatous hyperplasia

•sites: head

•treatment: surgery

Sebaceous Gland Adenocarcinoma

•rapid growth rate and ulceration

•site: perianal

•gross appearance: solitary, poorly circumscribed, ulcerated, and invasive

•local tumor recurrence and metastasis risk varies from low to 70%-90%