An aggressive extramedullary cutaneous plasmacytoma associated with extreme alterations in the innate immune system

The role of natural killer (NK) cells in plasma cell diseases has not yet been fully characterized.

We present the case of a 47-year-old man with an extremely aggressive extramedullary plasmacytoma of the lung with associated cutaneous lesions, whose disease was accompanied by a significantly decreased number of NK cells (CD56+, CD16+, CD3-) in the peripheral blood, very low NK cell activity levels, and a decreased interleukin-2 production from cultured cells in vitro. Histology and immunohistochemistry of the lung and cutaneous lesions identified that the tumor was composed of clonal plasma cells which were CD38+++, CD138+++, lambda chain+, kappa chain-, and cytokeratin-. Bone marrow histology and cytology were initially normal. The disease progressed rapidly despite local radiotherapy and systemic chemotherapy, and the patient died shortly after diagnosis.

Cutaneous involvement in extramedullary plasmacytoma represents a clinically aggressive variant of plasma cell tumor, which runs a rapid course and has associated devastating effects on the patient's innate immune system.