Pleural Effusion in Pulmonary and Extrapulmonary Blastomycosis

Objective: Pleural effusion secondary to blastomycosis infection is an uncommon clinical manifestation of the disease. We undertook a retrospective study to assess the incidence and involvement of pleural effusion in patients with blastomycosis infection.

Study design: Institutional cytology and surgical pathology records were searched from December 1995 to October 2017 for cases of blastomycosis. The cytologic, surgical pathology, and clinical pertinent information was reviewed in detail.

Results: A total of 77 cases of blastomycosis infection were recorded, with a male-to-female ratio of 1.7:1.0. Forty-eight cases of blastomycosis were pulmonary (62.3%), while 29 cases of blastomycosis were found in extrapulmonary sites (37.7%). The diagnosis of pulmonary blastomycosis was established by 24 lung biopsies/wedge resections, 22 bronchial alveolar lavages, and 2 lung fine needle aspirations. The 29 cases of extrapulmonary blastomycosis included 13 cases of bone (44.8%), 8 cases of skin (27.6%), 6 cases of soft tissue (20.7%), and 2 cases of brain infections (6.8%). Twenty-eight of 48 pulmonary cases were complicated by unilateral or bilateral pleural effusion (58.3%) detected by imaging studies. Four of the 28 pleural effusions were aspirated and examined by cytology. Two of the 4 pleural fluid cytologies showed involvement by blastomycosis (50%). In the extrapulmonary blastomycosis group, 9 of 29 patients showed unilateral or bilateral pleural effusions (31.0%), including 4 cases of bone, 4 cases of skin, and 1 case of brain involvement. Only 2 of the 9 pleural effusions were aspirated for cytology study. One of the 2 pleural fluid cytologies showed blastomycosis (50%).

Conclusion: Pleural effusion detected by imaging is common in blastomycosis patients. Blastomycosis can involve pleural fluid in both pulmonary and extrapulmonary diseases. A broad infectious differential that includes blastomycosis should be considered to make a timely diagnosis and initiate antifungal therapy to prevent systemic infection and further dissemination of the disease.