Case Abstract

Paige Mackey
Oklahoma State University, '13

IMMUNOHISTOCHEMICAL EXPRESSION OF C-KIT PROTEIN IN CANINE CUTANEOUS PLASMACYTOMAS

*Paige E. Mackey (1), Catherine G. Lamm (2), and Gregory A. Campbell (3)

1 Department of Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater OK; 2 Veterinary Pathological Sciences, University of Glasgow, Glasgow, UK 3 Oklahoma Animal Disease Diagnostic Laboratory, Oklahoma State University, Stillwater, OK.

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c-KIT is proto-oncogene that encodes a tyrosine kinase receptor, KIT, that is expressed by normal cells as well as various neoplasms in both humans and animals. Most notably, c-KIT expression is used for diagnosis and grading of canine mast cell tumors. In this study, immunohistochemistry was used to determine if c-KIT expression occurs in canine plasmacytomas. The Universal Veterinary Information System database at the Oklahoma Animal Disease Diagnostic Laboratory was searched from January 1st, 2008 to March 1st, 2010 for any domestic canid with a cutaneous plasmacytoma. The routinely stained slides from 41 dogs were reviewed by two board-certified pathologists to confirm the original diagnosis and immunohistochemistry for KIT was performed.  Immunoreactivity for KIT was detected in 37/41 plasmacytomas. Immunoreactivity was defined as the percentage of plasma cells with a brown cytoplasmic staining pattern. Of the 41 neoplasms examined, 4 of those examined were diffusely immunoreactive for c-KIT.  The remaining 80% of cases (33/41) had variable immunoreactivity, ranging from 5% to 80% immunoreactive cells within the neoplastic population. Based on these results, KIT immunoreactivity should not be used to differentiate canine cutaneous round cell neoplasms.