Peritoneal blastomycosis. Blastomycosis is a systemic fungal infection caused by Blastomyces dermatitidis. Involvement of the peritoneum is unusual, with only two previously reported cases that occurred in association with disseminated disease. A single case of histopathologically proven blastomycosis involving the peritoneum is presented, as well as a short overview of previously published cases on gastrointestinal and peritoneal blastomycosis. The case is unique in that chronic peritonitis was the only manifestation of disease. The diagnosis was made by laparoscopy. 