Unusual primary osseous Hodgkin lymphoma in rib with associated soft tissue mass: a case report and review of literature

Hodgkin lymphoma (HL) typically presents as nodal lesion and may involve extranodal sites during the progression of the disease. Primary osseous HL without any lymph node association is extremely rare and only a few such cases have been described in the literature. We present a case of unusual primary HL in rib occurring in a middle-aged female patient. Computed tomography (CT) scan revealed an osteolytic lesion was located at the right second rib and was associated with a large soft tissue mass. There was no regional lymph node involvement. CT scan of neck and abdomen was performed and showed no pathologic findings, particularly no lymphadenopathy and organomegaly could be observed. Histologically, typical binucleated Reed-Sternberg (RS) cells and lacunar cells were scattered in the background of reactive inflammation with infiltration of lymphocytes, histiocytes and eosinophilic granulocytes. By immunohistochemistry, RS cells and lacunar cells were positive for CD15 and CD30 with typical membrane and paranuclear dot-like staining pattern. However, these cells were negative for Epstein-Barr virus detection by in situ hybridization. A diagnosis of primary osseous HL was made. The patient received systemic chemotherapy and local radiotherapy, and was on regular follow-up for 24 months. There was no sign of recurrence of tumor and lymph node or bone marrow involvement. Because there is a possibility of secondary bone involvement by systemic HL, strict histological analysis and thorough radiographic examination are suggested to be necessary for accurately diagnosing this tumor when it presents as a solitary bone lesion.