Clinical & Radiological Spectrum of Histoplasmosis in Dehli-NCR: A Retrospective Analysis and Evidence of Emerging Endemicity

Abstract

Background:
Histoplasmosis, caused by the dimorphic fungi Histoplasma capsulatum and acquired primarily through inhalation of spores from soil enriched with bird or bat droppings, has traditionally been considered rare in India. Recent reports, however, suggest rising recognition from previously non-endemic regions. This case series describes nine patients from Delhi-NCR, highlighting diagnostic challenges and signals of emerging endemicity.

Methods:
Nine patients with histopathologically confirmed histoplasmosis were retrospectively reviewed at a tertiary care centre in Delhi-NCR. Clinical presentation, radiology, diagnostic modalities, treatment, and outcomes were analyzed. Histopathology using Periodic acid-Schiff (PAS) and Gomori methenamine silver (GMS) stains confirmed the diagnosis in all cases.

Results:
Nine patients with a median age of 64 years were identified, with a male predominance (88.9%). Eight of nine patients were immunocompromised, either due to diabetes mellitus (77.8%), prior tuberculosis (55.6%), or other causes of immunosuppression. Most presented with cough (100%), fever (66.7%), weight loss (44.4%), hemoptysis (22.2%), chest pain, or non-resolving pneumonia. Radiologically, consolidation and cavitation were most common (66.7%), frequently mimicking pulmonary tuberculosis, mediastinal lymphadenopathy (44.4%), and occasionally complicated by pneumothorax or pleural effusion. All diagnoses were confirmed through tissue histopathology. Localized histoplasmosis responded well to azole monotherapy (66.7%), while disseminated disease was associated with poorer outcomes and often required amphotericin B in combination with or followed by an azole. Seven patients (77.8%), improved clinically and radiologically; two patients succumbed to progressive disease (22.2%).
Conclusion:
Histoplasmosis in the Delhi-NCR region commonly masquerades as tuberculosis and is likely underrecognized. A high index of suspicion in patients with non-resolving pneumonia or cavitary lung lesions, early tissue diagnosis, and timely institution of antifungal therapy are critical to improving outcomes. The present series supports the possibility of emerging endemicity of histoplasmosis in North India and underscores the need for heightened clinical awareness and further epidemiological studies.