+ 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%