Primary cutaneous plasmacytomas are rare and little is known about their treatment and progression. We describe for the first time the predilection of primary cutaneous plasmacytoma to occur in a scar or sites of trauma. We report an 89-year-old man who presented with a slowly expanding asymptomatic mass over his pacemaker implantation, 1 year after insertion. Further investigation ruled out multiple myeloma and histology confirmed it to be a cutaneous plasmacytoma. This was treated successfully by local radiotherapy after extraction of the pacemaker and implantation of a new pacemaker on the opposite side. The patient subsequently developed an additional cutaneous plasmacytoma over the new pacemaker site, followed by the development of progressive multiple myeloma. Primary cutaneous plasmacytoma can show predilection for sites of trauma or surgery. Surgical excision of the plasmocytoma and local radiotherapy may be a reasonable strategy in the first initially after pacemaker removal.