Primary non-Hodgkin's lymphoma of bone: poly-ostotic versus mono-ostotic subtypes

Primary non-Hodgkin's lymphoma of bone (PNHLB) accounts for less than 5% of all primary bone tumours and less than 1% of all non-Hodgkin's lymphoma. Due to its rarity, only a few retrospective studies have been published describing the prognosis and its treatment. We report our experience of 20 cases of PNHLB with their clinicopathologic correlation that were treated at our centre over a period of ten years. There were 16 cases of the mono-ostotic subtype and four cases of poly-ostotic subtype. All of these had a histological diagnosis of diffuse large B-cell lymphoma. The age of presentation was fifth to sixth decade. The mono-ostotic subtype commonly presented with the involvement of femur or humerus, while the poly-ostotic subtype commonly had paraparesis due to vertebral involvement. Cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP)-based chemotherapy was given to all patients, but definitive radiotherapy was used only in the mono-ostotic subtype. At median follow-up of 38 months (range 5-96 months), event-free survival was 81% and 25% with mono-ostotic and poly-ostotic subtypes, respectively. Thus poly-ostotic PNHLB is a distinctive entity with a poor prognosis, and larger studies are needed for better management of this subtype.