Treatment and Outcomes for Primary Cutaneous Extramedullary Plasmacytoma: A Case Series

Background Primary cutaneous plasmacytoma (pcp) is a rare disease, with few studies to guide therapy. Our primary study objective was to define treatments used for pcp; a secondary objective was to describe outcomes of patients, including disease recurrence and death. Methods An institutional cancer registry was used to identify cases for retrospective chart review. In a systematic review, treatments for, and outcomes of, all known cases of pcp were described. Results Three eligible cases identified at our institution; each patient had a solitary pcp. The systematic review identified 66 patients. Radiotherapy was the most commonly used primary treatment modality (31% of all patients; 42% for patients with solitary lesions), followed by surgery (28% of all patients; 36% for patients with solitary lesions). Median survival for all patients was 10.4 years [95% CI: 4.3 years to not reached], with a trend toward a decreased risk of death with solitary lesions compared with multiple lesions (hazard ratio: 0.37; 95% CI: 0.13 to 1.08; p = 0.059). For patients with solitary lesions, the median and recurrence-free survivals were, respectively, 17.0 years (95% CI: 1.7 years to not reached) and 11.0 years (95% CI: 2 years to not reached); for patients with multiple lesions, they were 4.3 years (95% CI: 1.3 to not reached) and 1.4 years (95% CI: 0.6 years to not reached). Disease recurrence, including progression to multiple myeloma, was the most common cause of death. Conclusions Compared with patients having multiple pcp lesions, those presenting with a single pcp lesion might experience longer overall survival. Local therapy (radiation or surgery) is a reasonable curative treatment for a solitary pcp lesion.