Clinical characteristics of histoplasmosis in Siriraj hospital

Background: Histoplasmosis is a rare infectious disease caused by Histoplasmosis capsulatum (H. capsulatum), a dimorphic fungus. Histoplasmosis is not endemic to Thailand. Cases of histoplasmosis are sporadic and mostly associated with HIV disease. Clinical characteristics and treatment outcomes of histoplasmosis in Thai patients have not been well described. Objective: To investigate the clinical characteristics and outcomes of patients with histoplasmosis at Siriraj Hospital in Bangkok, Thailand Material and Method: This retrospective investigation studied adult patients with histoplasmosis who attended Siriraj Hospital for treatment between 2002 and 2012 (11 years). Clinical characteristics, microbiological data, and treatment outcomes were analyzed. Results: Fifty-seven patients were included in the study. Twenty-one (37%) were culture-proven, 37 (64.9%) were male, and mean age was 37 years. Fifty-four (95%) patients had co-morbid diseases, of which HIV infection was the most common (85%), followed by autoimmune diseases. Mean CD4 count among HIV-infected patients was 40 (range: 1-320) cells/mm3. The most common clinical syndrome of histoplasmosis was progressive disseminated histoplasmosis (PDH) (86%), followed by chronic non-cavitary histoplasmosis (7%), and fungal synovitis (5%). Organ involvement included lungs (38%), oral cavity (4%), adrenal gland (2%), and heart valve (2%). Bone and joint infection was found in three patients, all of which were HIV-negative. Common clinical manifestations were fever (84%), weight loss (88%), anemia (63%), jaundice (16%), hepatomegaly (38%), splenomegaly (18%), lymphadenopathy (41%), and molluscum-like skin lesions (30%). Chest radiography was abnormal in 54% of patients, with 65% of those having bilateral pulmonary lesions. Interstitial infiltration was the most common radiographic finding (42%), followed by perihilar adenopathy (19%) and cavitary lesion (16%). Microscopic examination was positive for yeast-like organism in bone marrow and skin in 66% and 89% of patients, respectively. Budding yeasts were detected in all biopsied tissues obtained from oral lesions, synovium, and adrenal gland. Fungal cultures were positive from bone marrow, skin, and blood in 20%, 17%, and 5% of patients, respectively. All adrenal glands and heart valve vegetations sent for culture were positive. Fifty-one patients received amphotericin B deoxycholate followed by itraconazole, with clinical cure achieved in 86%. Survival rates at 6- and 12-month were 88% and 75%, respectively. Conclusion: PDH is the most common syndrome of histoplasmosis in Siriraj Hospital. Skin and bone marrow study are the most useful investigations for diagnosis. Effective treatment includes amphotericin B, followed by oral itraconazole.