B72-01 Disseminated Coccidioidomycosis Masquerading as an Invasive Soft Tissue Tumor

Abstract Introduction Coccidioidomycosis, also known as Valley Fever, is a dimorphic fungal infection endemic to the southwestern United States, Mexico, and parts of Central and South America. While usually asymptomatic, symptomatic cases typically involve the lungs and resemble community-acquired pneumonia. Disseminated coccidioidomycosis (DCM) occurs in 0.5-2% of cases, often affecting skin, soft tissue, meninges, or bone. Patients who are immunocompromised, or have diabetes, pregnancy, or certain ethnic backgrounds (African American, Filipino) have an increased risk for severe disease. We report a rare case of DCM presenting as a sternal mass. Case Presentation A 29-year-old African American female with asthma and 2 months postpartum was referred for evaluation of a painful, enlarging sternal mass. She reported two weeks of dyspnea, malaise, and intermittent night sweats, accompanied by the onset of a sternal mass and localized chest wall pain. The outside CT Chest reported innumerable scattered pulmonary nodules and a lytic 5.8 x 4.7 x 8 cm lesion of the manubrium with soft tissue extension into the anterior chest wall and adjacent musculature. Upon admission, vital signs and laboratory studies were normal. Empiric broad-spectrum antibiotics were initiated but discontinued after low suspicion for bacterial infection. Differentials included malignancy or disseminated infection. Repeat CT Chest showed a destructive manubrial lesion with soft tissue involvement and basilar opacities (Figure 1). Further imaging, including CT abdomen/pelvis and MRI brain, was unrevealing. A percutaneous ultrasound-guided biopsy was performed, and the patient was discharged with pain control and outpatient pulmonology follow-up. Histopathology revealed granulomatous inflammation with fungal organisms consistent with Coccidioides species. Oral fluconazole was initiated twice daily, with a planned duration of at least 12 months and close outpatient monitoring. Discussion Most cases of coccidioidomycosis are asymptomatic or present with mild symptoms. Our patient had several risk factors that placed her at risk for severe disease: African American race, recent pregnancy, and residing in southern Nevada. While skeletal involvement in DCM is common, it typically affects the vertebral column or distal extremities; sternal invasion is exceedingly rare. Bone involvement requires prolonged antifungal therapy, often longer than 12 months, and may necessitate surgical intervention depending on severity or location. This case underscores the importance of maintaining a broad differential diagnosis while having heightened suspicion for endemic disease when needed. This abstract is funded by: None