Abstract Background Coccidioidomycosis, commonly known as Valley Fever, is a fungal infection caused by Coccidioides immitis or Coccidioides posadasii. While endemic to the southwestern United States, its presentation often overlaps with bacterial pneumonia or malignancy, leading to diagnostic uncertainty. Pulmonary coccidioidomycosis presenting as a hilar or mediastinal mass is particularly rare and can closely mimic primary lung cancer or lymphoma on imaging. Case Presentation A 61-year-old Filipina woman with a history of hypertension, type 2 diabetes, and thalassemia minor, and no smoking history, presented with a two-week history of progressive cough, dyspnea, and fatigue. Initial chest radiography revealed right lower lobe pneumonia. Despite treatment with oral antibiotics, her symptoms worsened, prompting CT imaging that demonstrated complete right middle lobe atelectasis and a right mediastinal/hilar mass with confluence lymphadenopathy—raising strong concern for primary malignancy or lymphoma. She reported unintentional 7-lb weight loss, night sweats, and decreased appetite.She was admitted for further evaluation. Laboratory workup showed leukocytosis and microcytic anemia. Pulmonology was consulted, and bronchoscopy with endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) and bronchoalveolar lavage (BAL) were performed. Cytology was negative for malignancy. Fungal culture and serologic testing later confirmed Coccidioides species, consistent with pulmonary coccidioidomycosis.The patient was started on oral fluconazole with close outpatient follow-up. Her symptoms improved markedly over several weeks. Repeat imaging demonstrated resolution of mediastinal lymphadenopathy and reduction in the mass-like opacity. Discussion This case underscores an atypical manifestation of pulmonary coccidioidomycosis, initially indistinguishable from thoracic malignancy. While Coccidioides infections frequently present with pulmonary infiltrates or cavitations, the formation of a hilar mass with lymphadenopathy is uncommon. Filipinos, along with other certain ethnic groups, are at increased risk for disseminated or severe coccidioidomycosis, making early identification critical.Recognition of this fungal infection’s diverse radiographic presentations is vital, particularly in endemic regions. Misdiagnosis may result in unnecessary invasive procedures or delayed antifungal therapy. Conclusion This case highlights the importance of considering coccidioidomycosis in the differential diagnosis of pulmonary masses, especially in endemic areas and among high-risk ethnic groups. Early integration of fungal testing in atypical pneumonias or mass-like pulmonary presentations can prevent misdiagnosis and guide timely, appropriate treatment. This abstract is funded by: None
Varias et al. (Fri,) studied this question.