Clinicopathologic profile of extramedullary plasmacytoma in Central Valley.

Abstract

e20551 Background: Extramedullary Plasmacytoma (EMP) occurs when neoplastic plasma cells cross the bone cortex to the surrounding soft tissue or spread hematogenously to other organs. The incidence rate of isolated plasmacytoma is reported to be 2-5% of plasma cell neoplasm. The skeletal system, head and neck are common organs involved. Our study evaluates the clinicopathologic characteristics of patients with EMP, with or without multiple myeloma (MM) in Central Valley, California. Methods: This is a retrospective review of 354 patients diagnosed with plasma cell dyscrasias, from January 2000 to January 2018. 33 patients had pathologically confirmed EMP and were evaluated for clinicopathologic data. Results: The incidence rate of EMP during the study period was 9%. Of the 33 patients diagnosed with EMP, 26 (78%) were associated with MM. The mean age at diagnosis was 62.6 years with no significant difference in mean age at diagnosis between patients with isolated EMP and EMP with MM (p = 0.23). Of the 33 patients, 11 (36.7%) were Hispanic, 11 (36.7%) were Caucasian whilst the rest constitute other minorities. This mirrored the 2010 population profile of the county. There are no statistically significant ethnic differences in the incidence of EMP with OR of 1.96 (p = 0.84). Compared to isolated EMP where aerodigestive system is most common site, bone with soft tissue (21%) is the most frequent site of involvement in EMP with MM [Table]. 9 (37%) patients were found to have IgG kappa as most common serum immunofixation finding in EMP with MM. FISH displayed high risk cytogenetics in 11 (45%) patients in the group. 91% of patients with EMP and MM were treated with chemotherapy alone or in combination with surgery or radiation. The median overall survival of patients with isolated EMP and EMP with MM was 46 months [95% CI: 11.2-80.9] and 55 months [95% CI: 16.3-93.7] respectively. Conclusions: The number of patients with isolated EMP is small for comparison with patients with EMP and MM. EMP occurs frequently with MM either at diagnosis or with disease progression. It tends to have high risk cytogenetics and may signify more aggressive disease. [Table: see text]