Plasmacytoma: A Rare Case of Bone Malignancy

Solitary Plasmacytoma is a rare disease characterized by a localized proliferation of neoplastic monoclonal plasma cell, without evidence of systemic disease. It can be subdivided into solitary bone plasmacytoma if the lesion originates in bone, or solitary extramedullary plasmacytoma if the lesion involves a soft tissue. A 25-year-old male patient is admitted to our clinic with hip pain. In the biopsy performed from the left iliac bone, atypical cells with rounded nuclei, granular chromatin and eccentrically located, extensive cytoplasm, and plasma cell morphology were observed. Because of CD38 positivity and plasma cell morphology, kappa lambda examination performed by CISH showed kappa positive lambda negative. Plasmocytomas are easily recognizable on tissue sections if the plasma cells are not poorly differentiated (plasmoblastic or anaplastic). In poorly differentiated lesions, immunohistochemical staining or in situ hybridization studies of kappa and lambda light chains can be performed