Multicentric Oral Plasmacytoma in 3 Dogs

Abstract

Oral extramedullary plasmacytomas (EMP) are locally aggressive tumors in the dog that rarely metastasize. They represent 5.2% of all canine oral tumors and 22.0 to 28.0% of all EMPs diagnosed are in the oral cavity. EMPs consist of neoplastic plasma cells that do not arise from the bone marrow. No relationship between EMP and the development of multiple myeloma has been determined in dogs. Complete surgical excision is the primary treatment for this neoplasm and is usually curative. Multiple oral EMPs within the same patient have been rarely reported with tumors arising in the same location in the mouth. To the authors' knowledge, multicentric oral EMP, as described in the following cases, has not been reported in the dog.

Long‐term survival of a dog diagnosed with a primary multicentric hepatic plasma cell tumour treated with surgery and chemotherapy

“…Several features of the current case appear to be unique including the multicentric presentation and the long‐term outcome with surgery and chemotherapy. The multicentric presentation may have been attributable to intraorgan metastasis of a single primary hepatic EMP or a true multifocal presentation as reported for oral and cutaneous EMP 4,20 . However, the long‐term outcome suggested a non‐aggressive disease with a low likelihood of metastasis.…”

“…Localised cutaneous and oral EMPs are associated with an excellent prognosis when adequate local treatment is carried out, 4–6 whereas gastrointestinal non‐colorectal EMPs tend to have a more guarded prognosis 7–9 . Information on the behaviour of EMPs in other locations is scarce and consists of single case reports or small case series 11–17 .…”

“…EMP excisions, even when marginal, are often associated with a low recurrence rate and a fair prognosis. 5,14 Although surgery is the treatment of choice for almost all solitary EMP, 4,5 this dog could have potentially been managed with chemotherapy alone since PCTs are often chemotherapyresponsive tumours. 3,20 In the present case, melphalan was well tolerated when used for 6 months as single-agent chemotherapy.…”

“…When localised to the bone, EMP is usually classified as solitary osseous plasmacytoma (SOP) 2 . Cutaneous and oral EMP are usually benign in clinical behaviour, and localised therapies are almost always associated with an excellent prognosis 4–6 . Gastrointestinal EMP and SOP are associated with a more aggressive clinical behaviour; gastrointestinal non‐colorectal EMP, in particular, tends to be associated with regional lymph node metastasis, and in humans, SOP tends to progress to MM 7–10 .…”

Atypical, non‐secretory presentation of multiple myeloma in a dog

“…Plasmacytomas are reported to occur in the oral cavity; however, it is rare for them to occur as part of MM. Indeed, typically they are solitary and have an excellent prognosis with surgery and/or radiation (Wright and others 2008; Smithson and others 2012; Culp and others 2013). Similar to the case for the radius lesion being the primary site, this is plausible also for the oral mass, but it is just as possible that it is one of the multifocal lesions of MM in a slightly atypical site and of atypical appearance.…”