Coccidioidomycosis imaging reveals a broad spectrum of clinical and radiologic manifestations, ranging from simple limited pulmonary disease to severe disseminated multiorgan infections. The dimorphic fungi Coccidioides immitis and Coccidioides posadasii induce this disease, which is endemic to the southwestern United States and parts of Mexico. Consequently, doctors practicing in non-endemic areas, like India, must consider this diagnosis in patients with a relevant travel history. Inhalation of arthroconidia from disturbed soil initiates the infection. Once inside the host, the arthroconidia transform into spherules, which in turn trigger a host cell-mediated immune response. However, an inadequate response allows the organism to convert into endospores, hence enabling hematogenous and lymphatic dissemination throughout the body. Therefore, the body’s immune response ultimately dictates whether the infection remains localized or becomes widely disseminated.
Pulmonary Manifestations of Coccidioidomycosis Imaging
The airborne route of transmission gives the infection a high propensity for pulmonary involvement, which is the most common disease manifestation overall. Acute pulmonary coccidioidomycosis appears on CT with features such as nodules, lobar or segmental consolidation, and multifocal consolidation. Moreover, mediastinal adenopathy or pleural effusions often accompany these acute parenchymal findings. Because coccidioidomycosis symptoms can mimic other prevalent infectious diseases, especially tuberculosis, correlation with travel history and serology is critical for timely diagnosis. Indeed, the disease can closely resemble tuberculosis or histoplasmosis. Chronic pulmonary disease may also develop in a small percentage of patients. Chronic changes on imaging include residual nodules, chronic cavities, localized fibrosis, and calcified lesions. Thus, imaging remains crucial for monitoring disease progression and treatment response. Furthermore, long-standing disease may result in significant residual abnormalities requiring prolonged antifungal therapy.
Disseminated Coccidioidomycosis Imaging Features
Extrapulmonary dissemination is rare, generally occurring in only 1% to 5% of patients; however, it affects virtually any organ system. Musculoskeletal involvement is common in cases of dissemination. Specifically, discitis-osteomyelitis is a frequent manifestation. Notably, this often demonstrates relative disk sparing, analogous to the pattern observed in tuberculosis or other causes of atypical infectious spondylitis. Conversely, some cases may show disk space destruction, mimicking pyogenic spondylitis. When osteomyelitis involves the appendicular skeleton juxta-articularly, it can progress to septic arthritis. Less common musculoskeletal features include fungal tenosynovitis and soft-tissue abscesses.
Neurologic involvement is frequent in disseminated disease. Complications include meningitis, cerebritis, and abscess formation. Consequently, these neurologic issues often induce vasculopathic and neuropathic sequelae, becoming a leading cause of morbidity and mortality in disseminated cases. When suspecting coccidioidal spondylitis, clinicians must image the entire neuroaxis due to the potential for skip lesions. Other systems are less commonly involved; these conditions include pyelonephritis, peritonitis, lymphadenitis, and endocarditis. Untreated disseminated disease, especially meningitis, is often fatal, emphasizing the need for prompt and accurate imaging interpretation.
Frequently Asked Questions
Q1: How is Coccidioidomycosis transmitted, and why does it affect the lungs most often?
Coccidioidomycosis is transmitted when humans inhale airborne arthroconidia that are disturbed from the soil. The respiratory tract is the primary entry point; therefore, the infection shows a strong propensity for initial pulmonary involvement, which is its most common manifestation.
Q2: What is the significance of “relative disk sparing” in coccidioidal discitis-osteomyelitis?
Relative disk sparing is an important imaging feature because it suggests a more indolent infectious process, which is typical of fungal infections like Coccidioidomycosis or tuberculosis, rather than a rapidly destructive pyogenic bacterial infection.
Q3: Which patient population is at highest risk for Coccidioidomycosis dissemination?
Dissemination is rare (1%-5%) but the risk is significantly higher in individuals with altered cellular immunity due to conditions like HIV infection or in patients undergoing corticosteroid therapy.
References
- Haug LP et al. Multisystemic Imaging Features of Coccidioidomycosis. Radiographics. 2026 Feb undefined. doi: 10.1148/rg.250064. PMID: 41610037.
- Demos TC et al. Classic and contemporary imaging of coccidioidomycosis. AJR Am J Roentgenol. 2003 Jun;180(6):1481-93.
- Lee N et al. Pulmonary Coccidioidomycosis: Pictorial Review of Chest Radiographic and CT Findings. Radiographics. 2011 Nov-Dec;31(7):1939-55.
- Multisystemic Imaging Features of Coccidioidomycosis | RadioGraphics. RSNA. 2026 Jan.
- Galgiani JN. Coccidioidomycosis. MSD Manual Professional Edition. Last updated Mar 2024.
- Verghese S et al. Coccidioidomycosis in India: report of a second imported case. Med Mycol. 2002 Aug;40(4):307-9.