Solitary phalanx plasmacytoma relapse with disseminated extramedullary plasmacytomas and myeloma after short duration of remission.

Solitary bone plasmacytomas account for 5-7% of multiple myeloma cases and are assumed to have a fairly good prognosis, with a long duration of relapse-free survival after primary local treatment. Isolated phalanx plasmacytoma is a very rare entity, because involvement of extremities is seen in less than 1% of all solitary bone plasmacytomas, where they are usually localized centripedally, often in the axial skeleton. A 68 year old patient with a lytic lesion involving 5th phalanx was diagnosed as having a biopsy-proven solitary plasmacytoma, with a negative work-up for coexisting plasma cell dyscrasia. Three and a half months after completion of radiotherapy of the involved phalanx, the patient was readmitted with hypercalcemia, renal insufficiency and subsequently diagnosed as having atypical plasma cell infiltration of marrow, and plasmacytomas involving the right vocal cord and the premaxillary region, as well as pathological ulna fracture. Plasmacytoma of the phalanx, with extreme short duration of remission and an aggressive type of clinical relapse, is in sharp contrast with the natural stable course of a solitary plasmacytoma where the use of systemic treatment is subject to intense debate.