Spontaneous regression and regrowth of central nervous system lymphomatoid granulomatosis: case report.

A 74-year-old woman presented with central nervous system (CNS) lymphomatoid granulomatosis (LYG) that spontaneously regressed and then regrew shortly thereafter. Initial magnetic resonance imaging studies showed a well demarcated, round, enhanced lesion with perifocal edema in the left temporal lobe. The enhanced lesion and perifocal edema had drastically regressed without treatment at follow-up examination. Two months later, the lesion reappeared and was larger, so was completely removed via left fronto-temporal craniotomy. The histological diagnosis was CNS LYG. CNS LYG should be considered in the differential diagnosis of spontaneously regressing brain tumors.