A densely cellular tumor composed of sheets of malignant round cells exhibiting eccentric nuclei, coarse chromatin, and moderate amounts of amphophilic cytoplasm. Given the morphologic features, plasma cell myeloma is the primary consideration; however, for confirmation of this possibility and exclusion of the other less like possibilities, marker study (CD138, MUM1, EMA, CD20, LCA, CK, Synaptophysin, CD99, SATB2).
Pathologic fracture of the left humeral neck, MRI-identified cystic lesion.
Soft tissue fragments collectively measured 5.5x5x1 cm, totally embedded.
Left humeral neck lesion, biopsy: