Canine Extramedullary Plasmacytoma: A Round-Cell Tumor Outside Bone Marrow

A pink or red raised skin nodule, an oral mass, bleeding, ulceration, licking, eating difficulty, or a gastrointestinal sign may occur depending on site. A round, smooth appearance is not diagnostic.

Skin of the head, ears, limbs, and other sites and the oral cavity are commonly discussed. Less common gastrointestinal or other extramedullary sites can have different behavior.

Fine-needle aspiration may identify a plasma-cell population. Histopathology confirms architecture and margins and may prompt additional testing when features are atypical. Blood, urine, imaging, or bone-marrow assessment is selected only when systemic disease is a concern.

Uncontrolled bleeding, airway or swallowing difficulty, collapse, or severe GI signs needs urgent care. A stable skin nodule still needs sampling because other round-cell tumors can look similar.

Complete local excision is often discussed for accessible cutaneous lesions. Radiation or other local therapy may help selected incompletely removable sites. Systemic therapy is reserved for diagnoses and extent that justify it, not for every solitary skin lesion.

Track the treated site and check for new nodules without assuming they are the same diagnosis. Record oral comfort, appetite, stool, weight, wound healing, and any recurrence at the edge of the scar.