Pulmonary Histoplasmosis in a Referral Hospital in Mexico City

Abstract

Pulmonary histoplasmosis is caused by inhaling Histoplasma capsulatum. Less than 1% develops the disease. Risk factors in immunocompetent individuals are environmental exposures in endemic areas. The objective of this study is to determine the frequency, clinical, and microbiological characteristics in immunocompetent patients. A retrospective case series study of patients diagnosed with pulmonary histoplasmosis was performed in a respiratory care unit in Mexico City from 2000 to 2020. Each patient had bronchial lavage, and three patients underwent thoracoscopy for the lung tissue sample taken for the culture in Sabouraud Dextrose Agar. Twelve patients were identified, 8 males and 4 females; the predominant symptoms were fever (83%), dyspnea (75%), chest pain (66%), hemoptysis (41%), and weight loss (33%). The computed tomography of the chest showed the following findings: patchy consolidation 12 (100%), hilar adenopathy 6 (50%), pleural effusion 6 (50%), caverns 3 (25%), and solitary pulmonary nodule in one patient (8%). Histoplasma capsulatum was found in the culture of all twelve patients. The signs and symptoms of the disease are mediated by the immune status of the host. The clinical picture is often confused with systemic diseases. It is important to have a high degree of clinical suspicion to make a timely diagnosis.

Figure 1

Necrotizing pneumonia due to Histoplasma capsulatum. (a) Chest X-ray (PA), with the presence of heterogeneous consolidation with radio lucid areas inside. (b, c) Chest CT showing lobar consolidation, cavitation in the right upper lobe, and parahilar lymphadenopathy.

Figure 2

(a) Multiple nodular, hemorrhagic, and cavitated lesions scattered throughout the lung parenchyma. (b) Sabouraud's dextrose agar medium observing white, downy-looking colonies. (c) Direct examination with lactophenol cotton blue, in which thin, septate, hyaline hyphae with round, spiculated macroconidia were observed in a 40X image.