Canine Cutaneous Plasmacytosis: 21 Cases (2005-2015)

Area of Science:

• Veterinary Oncology
• Dermatology
• Internal Medicine

Background:

• Cutaneous plasmacytosis (CP) is a rare syndrome characterized by multiple cutaneous plasma cell tumors in dogs, distinct from multiple myeloma.
• Treatment protocols for canine CP are often adapted from human multiple myeloma therapies.
• This study represents the first case series describing CP in veterinary literature.

Purpose of the Study:

• To characterize the clinical presentation of cutaneous plasmacytosis in dogs.
• To evaluate treatment response rates and duration for canine CP.
• To determine the overall survival time for dogs diagnosed with CP.

Main Methods:

• Medical records of 21 client-owned dogs diagnosed with cutaneous plasmacytosis were retrospectively reviewed.
• Diagnosis was confirmed via histopathologic evaluation of cutaneous or subcutaneous lesions (≥3 lesions per dog).
• Dogs with suspected multiple myeloma were excluded from the study.

Main Results:

• Golden retrievers and Labrador retrievers were the most commonly affected breeds.
• The majority of dogs presented with numerous lesions, often described as raised, pink-to-red, and variably alopecic or ulcerated.
• Combined melphalan and prednisone achieved a 73.7% overall response rate (ORR), while single-agent lomustine showed a 71.4% ORR. Median progression-free interval was 153 days, and median survival was 542 days.

Conclusions:

• Alkylating agents, including melphalan and lomustine, are effective in achieving remission for canine cutaneous plasmacytosis.
• Corticosteroids were frequently used in combination therapies.
• Survival times observed in this study are comparable to those reported for dogs with multiple myeloma treated with similar chemotherapeutic agents.