Long‐term survival in a dog with suspected primary nodal plasmacytoma treated with surgical excision

Abstract An 8‐year‐old Staffordshire bull terrier presented for left submandibular lymphadenopathy. Cytology showed a monomorphic population of mature plasma cells suggestive of plasma cell neoplasia. On physical examination, no other lymphadenomegaly, cutaneous or oral lesions were found. Biochemistry showed mild total hypercalcaemia with normal ionised calcium. Lymphadenectomy was performed, and histological evaluation showed effacement of the lymph node by a neoplastic round cell population with a plasmacytoid appearance. Neoplastic cells labelled positively for MUM‐1, but were negative for CD3, CD79a and CD20. Computed tomography showed no evidence of systemic involvement. Adjuvant treatment was not pursued, and the dog was still alive 22 months after diagnosis without evidence of recurrence. Based on histopathology and immunohistochemistry in combination with the clinical outcome, a diagnosis of primary nodal plasmacytoma was favoured. Similar to its human counterpart, canine primary nodal plasmacytoma may be associated with an indolent behaviour and a good outcome with local treatment alone.