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Types of Cancer > OncoLink Vet > Veterinary Oncology > Tumors
Benign Melanocytic Tumors
Supported by the Savannah and Barry French Poodle Memorial Fund
Affiliation:
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
Introduction
Melanocytes are derived from neural crest cells. Precursor cells migrate from the neural crest to the epidermis in utero. The melanocytes develop dendritic cell processes and produce intracytoplasmic pigment granules. They send their dendritic processes up in between the keratinocytes and transfer the melanin to the keratinocytes.
Normal melanocytes inhabit the basal layer of the skin and the bulb of the hair follicle.
The two terms below are used to classify some of the different types of melanomas.
Junctional activity: the proliferation of nests or th èques (aggregations) of melanocytes along the dermo-epidermal junction.
Compound tumor: indicates that there is a junctional and an intradermal component to the tumor.
Melanocytic neoplasms can either be benign or malignant. To distinguish benign from malignant in dogs the following should be evaluated:
- the anatomic location of the tumor
- the cytologic features
- mitotic activity
- cell morphology
All histopathologic sections should be bleached prior to evaluation as the nuclear morphology may be obscured by the intracytoplasmic melanin granules.
Melanocytoma
Introduction
Definition: A benign tumor arising from melanocytes either in the epidermis, dermis, or adnexa, primarily the external root sheath of the hair follicles.
Synonyms: Cutaneous Melanoma, Dermal Melanoma, Benign Melanoma