Mycosis fungoides, so named because of the mushroom-like appearance of the tumors in humans, is a tumor of skin and mucous membranes. This term is considered archaic and confusing and has been replaced by canine epitheliotropic cutaneous lymphoma (ECL). The disease occurs in old dogs and has no breed predilection. The lesions evolve from a patch-plaque stage into a tumor stage in which distant metastasis is observed. There are two forms of the disease: cutaneous and oral.
Photos of mycosis fungoides in a Yorkshire terrier dog:
Because early signs of ECL may also occur in many other diseases, the condition is often referred to as great impersonator. Many dogs have itchiness, skin inflammation and seborrhea that do not respond to treatment. Other animals can develop ulcerations on the footpads and in the mouth. Early stages of epitheliotropic lymphoma can resemble inflammatory skin disease. The early stage of ECL progresses to plaques over a period of several months. Affected dogs become depressed, lethargic, have fever and lose appetite. Depigmentation, alopecia, plaques, ulceration, and crusting develop.
The prognosis is poor for both forms of lymphoma. Recurrence of disease is very common despite various treatments. Generalized epitheliotropic lymphoma is often treated with a five-drug chemotherapy. Palliative therapy, such as administration of glucocorticoids and antibiotics combined with antiseborrheic and antibacterial shampoos can temporarily improve the patient's quality of life. Radiation treatment may be helpful, with or without systemic chemotherapy, depending on the stage of disease. However, there is no evidence that the therapies extend the lifespan of a dog diagnosed with mycosis fungoides. Retinoid therapy has been used but with unpredictable success. Surgical removal of the tumors is impossible because such extensive areas of the body are usually involved.
Yorkshire terriers are predisposed to skin diseases and disorders
- Elizabeth A. Nesbit, DVM; Perry J. Bain, DVM, PhD; Nicole C. Northrup, DVM, and Kenneth S. Latimer, DVM, PhD. Canine Round Cell Tumors
- Bernard F. Feldman, Joseph G. Zinkl, Nemi Chand Jain. Schalm's Veterinary Hematology
- Epitheliotropic cutaneous lymphoma (mycosis fungoides) in a dog