Sebaceous epithelioma

(Click on image thumbnails to enlarge).

Typical sebaceous epithelioma in a ferret. Small, fleshy warty growth with small scabs, probably from self-trauma. (Photo courtesy of Michele Abel Focer)
Very aggressive looking neoplasm at the lateral canthus. Initially thought to be severe ocular trauma. Just a sebaceous epithelioma! (Photo courtesy of Mary G. Mewton)
The same neoplasm when scrubbed and cleaned for surgery - doesn't look so bad now, does it?!(Photo courtesy of Mary G. Mewton)
Same ferret as in the previous picture, with another sebaceous epithelioma. These tumors may have central cavitation, and are more than occasionally diagnosed as spider bites or other envenomations.(Photo courtesy of Mary G. Mewton)
Close up of a sebaceous epithelioma on the paw of a ferret. Note the cauliflower, warty appearance that is characteristic of these neoplasms. (Photo courtesy of Mary Lou Steinweg)
For those interested in histopathology - very characteristic lobular pattern of immature basaloid cells thoughout which are scattered islands of well differentiated sebaceous cells.
Also occasionally referred to as sebaceous adenomas or basal cell tumors, sebaceous epitheliomas are the most common cutaneous neoplasm in the ferret. These raised, warty tumors often look very ugly, belying their meek and mild nature. More than one practitioner has been fooled into believing that these ugly tumors are some devastating disease, only to be pleasantly surprised when the pathology report comes back.

Sebaceous epitheliomas are invariably benign, and pose no significant health risk, other than that incurred with general anesthesia and surgery. However, they may occasionally misdiagnosed as malignancies (the early literature refers to these as "basosquamosebaceous carcinomas" -- an incorrect assessment as well as a poor appellation), usually as a result of associated inflammation and proliferation of adjacent dermal elements.

The precise diagnosis of this tumor as sebaceous epithelioma vs. sebaceous adenoma vs. basal cell tumor is primarily a matter of semantics, and is based on the number of cells showing sebaceous (a type of oil gland in the skin) differentiation. Tumors with a high number of sebaceous cells are often labelled as "sebaceous adenoma", neoplasms with few to no cells are labelled as "basal cell tumors", and the vast majority have about 10-20%, and are classified as "sebaceous" epithelioma.

Regardless of the name, the treatment is always the same - surgical excision and the prognosis is generally excellent. These tumors rarely invade deeply, and are usually removed without complication. Most surgical excisions are easily closed, but if the tumor has grown to a large size, the incision may have to heal as an open wound due to a lack of loose skin to sew up. No matter - it'll usually heal, and heal well.

If these neoplasms are always benign, why should we remove them? Look at these pictures. Untreated, they will continue to grow, get uglier, and serve as a source of irritation for the ferrets, and may eventually become a portal of entry for infection as a result of continuous self-trauma. In two cases in my archive, a malignant squamous cell carcinoma arose in longstanding tumors. Catch them early and the surgery is a snap.

References:

1.  Williams BH and C. Weiss. Neoplasia. In: Ferrets, Rabbits and Rodents - Clinical medicine and surgery, Carpenter J, Quesenberry KE (eds.), Saunders, Philadelphia, 44-52, 2002 (In press.)

2.Parker GA, Picut CA. Histopathologic features and post-surgical sequelae of 57 cutaneous neoplasms in ferrets (Mustela putorius furo). Vet Pathol 30:499-504, 1993. 3. Li X, Fox JG et. al.  Neoplastic diseases in ferrets (Mustela putorius furo):  a review of Veterinary Medical Data Base (1968-1997).  JAVMA (212): 1402-1406, 1998.

Bruce Williams, December 2001

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