[Primary bone anaplastic large cell lymphoma]

Anaplastic large cell lymphoma (ALCL) is a neoplasia of T-cell or null-cell origin accounting for approximately 3% of non-Hodgkin lymphomas in adults and 10-30% of lymphomas in children. It involves the lymph nodes as well as various extranodal sites, but the involvement of bone as either the primary or secondary site of spread, is rare.

A 47-year-old male presented with an ALCL and multiple bone lesions involving the vertebrae, ribs, and iliac bone, with no other site of involvement. Histologic findings included interstitial and focal bone infiltrate consisting of large pleomorphic cells with an inflammatory background and marked fibrosis. There was immunohistochemical expression of CD30, EMA, CD45RO, CD43, CD8, Glut-1 and ALK-1.

There are 20 reported cases of ALCL (T/null cell) arising from the bone. To diagnose primary bone lymphoma it is necessary to first exclude systemic lymphoma of the lymph nodes or the skin with bone spread. The differential diagnoses include osteomyelitis, small round cell tumors, mainly Ewing sarcoma/PNET, metastatic carcinoma, melanoma, Hodgkin lymphoma and Langerhans' cell histiocytosis. In this case, the differential FDG accumulation in the lesions observed in the PET-CT was associated with the degree of Glut-1 expression.