Solitary plasmacytoma of the metacarpal bone in an adolescent. Solitary plasmacytoma of the bone (SPB) is a plasma cell neoplasm that usually presents as a lytic lesion mainly localized within the axial skeleton. The occurrence of SPB in young individuals is exceedingly rare, but has been sporadically reported before. We report a case of SPB involving metacarpal bone in a 16-year-old male with a prior history of trauma at the same site.