Primary pulmonary lymphoma diagnosed by gene rearrangement: report of a case.

We report herein the case of a 59-year-old asymptomatic man who was referred to our department for investigation of an abnormal shadow detected on a routine chest roentogenogram. Computed tomography (CT) showed an infiltrative shadow and air bronchogram in the right middle lobe without mediastinal lymphadenopathy, and a right middle lobectomy was performed with hilar and interlobar lymph node excision. Microscopically, the tumor consisted of small lymphoid cells without atypia, admixed with neutrophils and other mononuclear cells, but there was no invasion of the bronchial cartilage or visceral pleura, or any lymph node involvement. Most of the tumor cells were positive for L26 and some for UCHL-1. Although a germinal center was not seen, pseudolymphoma could not be ruled out. Southern blot analysis of the frozen tissues revealed clonal rearrangements of the immunoglobulin heavy-chain JH and light-chain J kappa, whereby the tumor was diagnosed as malignant lymphoma of the small lymphocytic B-cell type. Thus, when such lymphoproliferative diseases which are difficult to diagnose are encountered, frozen tissue should be preserved for genetic analysis.