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Cutaneous plasmacytoma with Mott cell differentiation in a dog
Cheryl L Auch1, Alyona Michael2
1Departments of Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
Insights
A rare canine plasma cell tumor with Mott cell differentiation was identified in a Yorkshire Terrier. This cytologic and histopathologic study describes a unique case of this neoplasm in veterinary medicine.
Area of Science:
- Veterinary Pathology
- Canine Neoplasia
- Cytopathology
Background:
- Plasma cell tumors are common in dogs, typically affecting bone marrow or extramedullary sites.
- Mott cells, characterized by intracytoplasmic immunoglobulin inclusions (Russell bodies), are typically associated with chronic inflammation or certain types of plasma cell neoplasms.
- Differentiation between plasma cell tumors and B-cell lymphomas can be challenging based on cytology alone.
Abstract:
Cytologic evaluation of aspirate slides from a small, <1-cm, interdigital mass on a 9-y-old, spayed female Yorkshire Terrier revealed a proliferation of discrete, round cells containing few-to-many, variably sized, round, eosinophilic, cytoplasmic inclusions. The top differentials based on the cytologic findings were either a plasma cell tumor or a B-cell lymphoma with Mott cell differentiation. The unencapsulated, well-demarcated, multilobulated round-cell neoplasm was completely excised. Immunohistochemical stains were performed to further characterize the neoplasm, which had immunolabeling for multiple myeloma oncogene 1 and vimentin, but did not react with CD3, CD20, melan A, or ionized calcium-binding adapter molecule 1, nor with a Giemsa special stain. Ultrastructurally, the cytoplasmic granules had Russell body-like morphology. A solitary, cutaneous plasmacytoma with Mott cell differentiation has not been described previously in veterinary medicine, to our knowledge.
