Pulmonary Coccidioidomycosis: Pictorial Review of Chest Radiographic and CT Findings

Abstract

Pulmonary coccidioidomycosis is a fungal disease endemic to the desert regions of the southwestern United States, Mexico, Central America, and South America. The incidence of reported disease increased substantially between 1998 and 2011, and the infection is encountered beyond the endemic areas because of a mobile society. The disease is caused by inhalation of spores of Coccidioides species. Individuals at high risk are those exposed to frequent soil aerosolization. The diagnosis is established by direct visualization of mature spherules by using special stains or cultures from biologic specimens. Serologic testing of anticoccidioidal antibodies is used for diagnosis and treatment monitoring. The infection is self-limited in 60% of cases. When the disease is symptomatic, the lung is the primary site of involvement. On the basis of clinical presentation and imaging abnormalities, pulmonary involvement is categorized into acute, disseminated, and chronic forms, each with a spectrum of imaging findings. In patients with acute disease, the most common findings are lobar or segmental consolidation, multifocal consolidation, and nodules. Adenopathy and pleural effusions are also seen, usually in association with parenchymal disease. Disseminated disease is rare and occurs in less than 1% of patients. Pulmonary findings are miliary nodules and confluent parenchymal opacities. Acute respiratory distress syndrome is an infrequent complication of disseminated disease. The acute findings resolve in most patients, with chronic changes developing in approximately 5% of patients. Manifestations of chronic disease include residual nodules, chronic cavities, persistent pneumonia with or without adenopathy, pleural effusion, and regressive changes. Unusual complications of chronic disease are mycetoma, abscess formation, and bronchopleural fistula. Patients in an immunocompromised state, those with diabetes mellitus, pregnant women, and those belonging to certain ethnic groups may show severe, progressive, or disseminated disease.

Top Questions in the Diagnosis and Treatment of Coccidioidomycosis

“…Serologic testing for coccidioidomycosis is often negative, as these nodules represent residua of past infection. The features of these nodules on CT do not allow easy distinction from malignancy, as they may be spiculated, have irregular margins, and typically do not calcify [45]. Chronic cavitary disease may also be mistaken for cavitary malignancy.…”

Coccidioidomycosis: Recent Updates

“…36,37 Pulmonary coccidioidomycosis often has associated intrathoracic lymphadenopathy with hilar and/or mediastinal nodes enlarged in up to 20% of patients undergoing computed tomographic (CT) imaging. 38 Traditionally, lymphadenopathy was thought to demonstrate regional spread from the pulmonary parenchyma to the lymphatic system and represent early disseminated disease. However, further studies have disproven this presumed association.…”

“…A small proportion of patients with acute pneumonia will develop chronic fibrocavitary disease. 38 Patients experience persistent cough and sputum production as well as fevers, night sweats, and weight loss. 41 In most cases, serological testing will remain positive.…”

Radiologic Imaging Techniques for the Diagnosis and Management of Invasive Fungal Disease

“…Chronic pulmonary coccidioidomycosis causes nodules, fibrosis, bronchiectasis, and/or cavities that can be thick or thin walled. Diffuse reticulonodular or miliary nodules are also seen in disseminated disease [56][57][58]. Extrapulmonary sites of infection include bone, brain, and skin.…”