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Basosquamous Carcinoma

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Supported by the Savannah and Barry French Poodle Memorial Fund
University of Pennsylvania School of Veterinary Medicine
Last Modified: August 21, 2005

Michael H. Goldschmidt, MSc, BVMS, MRCVS, Diplomate ACVP Professor and Head, Laboratory of Pathology and Toxicology Chief, Surgical Pathology Department of Pathobiology
Frances S. Shofer, PhD, Adjunct Associate Professor of Epidemiology and Biostatistics

Definition: A low-grade malignancy composed of basal cells with foci of squamous or follicular infundibular differentiation.

Epidemiology

Clinical Presentation/Physical Exam Findings

• an exophytic (growing outward from the skin) growth, freely movable over the subcutaneous tissue
• seen less often on the head and neck than trichoblastomas
• more are seen on other body sites

Tumor Pathology

Gross Findings

• extensions into the deep dermis and subcutaneous tissue
• cut surface of the tumor may be white or pigmented

Microscopic Findings

• multilobulated mass occupies and infiltrates the dermis 
• may have association with the epidermis
• at the periphery of the lobules are the basaloid cells
• in the center of the lobules, cells show abrupt keratinization
• keratinized cells display atypia
• numerous mitotic figures may be observed
• melanin may be present in the peripheral basaloid cells

Clinical Behavior

Basosquamous carcinomas may recur at the site of excision. Metastasis has not been reported with basosquamous carcinomas.

References

• Goldschmidt, M.H., & Hendrick, M.J. (2002). Tumors of the skin and soft tissue. In D.J. Meuten (Ed.), Tumors in domestic animals 4 th ed (pp. 45-119). Iowa: Iowa State Press
• Goldschmidt, M.H., & Shofer, F.S. (1998). Skin tumors of the dog and cat. Woburn, MA: Butterworth-Heinemann
• Gross, T.L., Ihrke, P.J., & Walder, E.J. (1992). Veterinary dermatopathology: A macroscopic and microscopic evaluation of canine and feline skin disease. (pp. 327-485). St. Louis, Missouri: Mosby Year Book
• World Health Organization (1998). Histological classification of epithelial and melanocytic tumors of the skin of domestic animals (2 nd series, vol 3). Washington, DC: Armed Forces Institute of Pathology
• Yager, J.A. & Wilcock, B.P. (1994). Color atlas and text of surgical pathology of the dog and cat. Ontario, Canada: Mosby Year Book