Central nervous system involvement in pyothorax-associated lymphoma: ring enhancement on CT scan.

A 71-year-old male was diagnosed as having pyothorax-associated lymphoma (PAL), a rare hematological malignancy associated with artificial pneumothorax for the treatment of pulmonary tuberculosis. Because of the low incidence, its clinical features have not been fully clarified. The PAL lesion in this patient disappeared after local radiotherapy and corticosteroid treatment. However, 8 months after the initial diagnosis, he developed a variety of neurological disorders and low-grade fever. Neither recurrence of the primary pulmonary lesion nor nodal enlargement was observed. Immediate magnetic resonance imaging of the brain revealed a ring-enhanced mass, suggesting a brain abscess. However, through a stereotactic biopsy of the brain lesion, infiltration of PAL cells was identified. The brain lesion rapidly enlarged despite intensive radiotherapy, and he finally died of lymphoma progression. This case demonstrates that PAL may progress as a type of extranodal lymphoma, and that brain lesions may produce a ring-enhanced pattern on computed tomography.