A rare case of anaplastic variant of diffuse large B-cell lymphoma presenting as a lung primary.

Primary pulmonary lymphoma is an uncommon neoplastic disorder representing approximately 0.5% to 1% of primary pulmonary malignancies. The vast majority are of low-grade, mucosa-associated lymphoid tissue type. Primary diffuse large B-cell lymphoma of the lung is rare, though cases of the centroblastic and immunoblastic variants have been described. We present herein an interesting case of an 80-year-old man who presented with both respiratory and constitutional symptoms and was found to have a 4.5 cm left hilar mass with bilateral hilar and mediastinal lymphadenopathy on imaging. Endobronchial biopsy revealed an aggressive large cell lymphoma, with scattered large, bizarre-shaped nuclei resembling Reed-Sternberg cells, positive for CD20, PAX5, CD30, and MUM-1, consistent with an anaplastic variant of diffuse large B-cell lymphoma. Imaging showed no evidence of extrathoracic disease. Standard treatment with cyclophosphamide/vincristine/prednisone and rituximab resulted in significant clinical and radiological response and the patient remains in remission 21 months later. To the best of our knowledge, this modified Ann Arbor stage II2E primary pulmonary lymphoma, is the first description in the English literature of anaplastic variant of diffuse large B-cell lymphoma presenting as a lung primary.