adiaspiromycosis

Adiaspiromycosis is a rare fungal infection of the lungs caused by inhalation of adiaspores produced by environmental fungi of the genus Emmonsia, most often Emmonsia crescens and Emmonsia parva. The disease is characterized by a granulomatous reaction to large, thick-walled, non-replicating adiaspores that form within pulmonary tissue.

Pathogenesis involves the inhalation of conidia that convert into adiaspores in the alveoli. Unlike many other mycoses, adiaspores do not germinate into yeast or mold within the host; instead, they provoke granulomatous inflammation, which can lead to nodular lesions and, in some cases, calcification.

Epidemiology and presentation are variable. Adiaspiromycosis is uncommon and reported in diverse geographic regions. Most infections are asymptomatic and discovered incidentally on imaging or at autopsy. When symptoms occur, they may include chronic cough or mild dyspnea. Radiologic findings typically show solitary or multiple pulmonary nodules or nodular interstitial lesions, which can mimic histoplasmosis, sarcoidosis, or other granulomatous diseases.

Diagnosis relies on histopathology and integration of clinical and radiologic data. Lung tissue reveals large, thick-walled adiaspores within granulomatous nodules. Cultures are often negative or non-diagnostic, and serology is not routinely helpful. Molecular techniques can aid species identification in research settings. The differential diagnosis includes histoplasmosis, coccidioidomycosis, and sarcoidosis.

Treatment is generally not required for asymptomatic cases. For symptomatic or diagnostically uncertain nodules, management may involve observation or surgical excision of the lesion. Antifungal therapy has limited evidence of benefit. The prognosis is typically favorable, with lesions often remaining stable over time; disseminated disease is rare and occurs mainly in immunocompromised individuals. Adiaspiromycosis is not considered contagious between humans.