A retrospective study of canine oral extramedullary plasmacytoma over a 15‐year period (July 2004–July 2019): Treatment, histologic parameters and clinical outcomes

Abstract

A total of 45 cases of canine oral extramedullary plasmacytomas (EMPs) presented to a tertiary referral institution over a 15‐year period were examined. Histologic sections of 33 of these cases were examined for histopathologic prognostic indicators. Patients underwent variable treatment including surgical intervention, chemotherapy and/or radiation therapy. Long term survival was observed in the majority of dogs with a median survival time of 973 days (2–4315 days). However, almost 1/3 of dogs had progression of plasma cell disease, including two cases with myeloma‐like progression. Histologic characterization of these tumours did not reveal criteria to predict tumour malignancy. However, cases without tumour progression did not exceed 28 mitotic figures in ten 400× fields (2.37 mm2). All cases with tumour related death showed at least moderate nuclear atypia. Oral EMPs may represent a local manifestation of systemic plasma cell disease or singular focal neoplasia.

Cutaneous Plasmacytoma with Systemic Metastases in a Cape Serotine Bat (Laephotis capensis)

“…Indeed, in humans, although EMPs generally have a good prognosis, 11–36% of cases have been reported to proceed to MM [ 40 , 41 , 42 ]. Some studies in canines have found EMPs tend to be benign (although oral EMPs are locally aggressive), carrying an excellent prognosis following complete surgical excision [ 1 , 2 , 43 , 44 ], although a recent study found that up to a third of cases had a progression of plasma cell disease, with two cases showing myeloma-like progression [ 45 ], and there are occasional case reports of dogs with EMPs showing progression to a disseminated myeloma [ 46 ]. However, cutaneous involvement in patients with MM is very uncommon and usually occurs in the late stages of the disease, with the development of multiple skin lesions reflecting the increased tumour cell burden [ 47 , 48 , 49 ].…”

Recurrence of cutaneous plasmacytoma in a dog with immune-mediated thrombocytopenia

“…EMP progresses to multiple myeloma in approximately 30% of patients in human medicine 4,5 . However, the patient shows no corresponding symptoms regarding multiple myeloma, and serum globulin level is normal without monoclonal spike.…”