Pulmonary cryptococcosis: atypical results in the serum test for cryptococcal antigen.

Two cases of pulmonary infection with Cryptococcus neoformans are reported. In both patients the cryptococcal antigen titres remained positive following initiation of effective therapy, and despite clinical evidence of resolution of disease. The possible causes for these findings are discussed and it is suggested why this atypical serological response does not necessarily indicate dissemination or active infection.