Lymphomatoid granulomatosis involving the central nervous system: complication of a renal transplant with terminal monoclonal B-cell proliferation.

A 33-year-old man, an immunosuppressed renal allograft recipient, developed fever of unknown etiology, multiple pulmonary densities, space-occupying lesions in the liver, confusion, disorientation, and seizures with cerebral infarcts. At autopsy, changes classical of active lymphomatoid granulomatosis (LYG) were found in the brain but those studied in the lungs and liver were in the healing phase. In addition, one cerebral focus in the right temporo-occipital lobe showed a lymphomatous transformation. Immunofluorescence studies done on this focus showed monoclonal IgG-lambda cytoplasmic staining in the perivascular infiltrate. Immunoperoxidase studies confirmed the monoclonal nature of this focus but showed a polyclonal pattern in the other foci. This finding is discussed along with the relationship between LYG and lymphoma.