The spectrum of pathogens in 187 cases of pulmonary fungal disease diagnosed by histopathology-a retrospective analysis

Abstract

Objective: To investigate the spectrum of pathogens causing lung fungal disease diagnosed by histopathology through histochemical special staining, compared to the fungal culture results, and to further evaluate the diagnostic value of histochemical special staining in pulmonary fungal disease. Methods: We performed a retrospective analysis of 187 cases of pulmonary fungal disease diagnosed by histopathology in Peking Union Medical College Hospital from 2001 to 2015 (including 92 cases with pulmonary resection or open lung biopsy, 33 with percutaneous lung biopsy and 62 ones with fiberoptic bronchoscopic lung biopsy). All cases were treated with hexamine silver, PAS, mucus carmine and acid-fast staining in addition to conventional HE staining. The clinical records and the fungal culture results were reviewed. Results: There were 103 male and 84 female patients, aged from 12 to 70 years [average (48±14) years]. There were 85 cases(45.5%) of pulmonary aspergillosis(including 60 cases of invasive infection and 25 cases of aspergilloma), 51 cases(27.3%) of pulmonary cryptococosis, 6 cases (3.2%)of pulmonary mucormycosis, 3 cases(1.6%) of pulmonary histoplasmosis, 3 cases (1.6%)of pulmonary candidiasis, and 2 cases (1.1%) of pneumocystosis, while in the remaining 37 cases (19.8%) the pathogens could not be clearly classified by microscopy due to limited tissue or degeneration. Among the 88 patients with pulmonary fungal disease diagnosed by histopathology from 2011 to 2015, 35 ones (39.9%) were detected by fungal culture (including lung biopsy, intraoperative swab, blood, bronchoalveolar lavage fluid and sputum, etc.). The diagnostic results of 18 cases were completely consistent between histopathological examination and fungal culture (18/35, 51.4%), while 13 cases (13/35, 37.1%) were diagnosed by histopathology but no fungi were cultured, and in 3 cases (3/35,8.6%) the culture was positive for fungi which could not be classified clearly by histopathology. In another case the pathogen was found to be Cryptococcus histopathologically but the lavage culture grew"candida", but the patient's blood cryptococcal antigen was positive. Conclusions: Among patients with histopathological diagnosis of pulmonary fungal disease, pulmonary aspergillosis was the most common, followed by pulmonary cryptococcosis, pulmonary mucormycosis, pulmonary histoplasmosis, pulmonary candidiasis and pneumocystosis. A small number of cases could not be classified by histopathology through histochemical special staining. There was a high consistency in discovering fungal pathogens between pathological histochemical special staining and culture method, but 37% pulmonary fungal disease diagnosed by histopathology were culture negative. In practice, the role of histochemical special staining in diagnosing pulmonary fungal disease should be paid more attention.