Title: Delayed Diagnosis of Disseminated Coccidioidomycosis Due to Misdiagnosis of Lymphoma: A Case Report.

Background: Coccidioidomycosis, or valley fever, is a fungal infection caused by inhaling Coccidioides imitis/posadasii. These fungi are endemic to the southwestern USA, Mexico, and Central and South America. Incidence has been rising, likely due to population growth, climatechange, and increased awareness. The infection presents diversely, with most cases being asymptomatic. About one-third develop pulmonary illness, and a small percentage experience dissemination to other body areas, commonly to skin, bone, and CNS, particularly in immunocompromised individuals and certain ethnic groups.

Case presentation: A 39-year-old Hispanic female with a history of non-Hodgkin's lymphoma and treated tuberculosis presented with painful ulcerative skin lesions. Initial labs showed mild leukocytosis, microcytic anemia, hypokalemia, and hypoalbuminemia. Imaging revealed bilateral pulmonary infiltrates, mediastinal adenopathy, and extensive lymphadenopathy. A skin biopsy report from Mexico indicated non-Hodgkin lymphoma, but no treatment was initiated at the time of diagnosis. A neck lymph node biopsy revealed fungal spherules and hyphae, consistent with coccidioidomycosis. Serology confirmed high titer IgG for Coccidioidomycosis. Further testing ruled out other conditions, including lymphoma. The patient started high-dose fluconazole. A lumbar puncture showed positive IgG for Coccidiomycosis in CSF, indicating CNS involvement. A repeated skin biopsy was negative for lymphoma, confirming disseminated coccidioidomycosis and ruling out lymphoma diagnosis. The patient was discharged on oral fluconazole and prophylactic TMP-SMX. Two months later, she was readmitted with worsening weakness and altered mentation. Despite adequate treatment, the imaging showed new lytic lesions in the left scapula and T2 body. Repeated lumbar puncture confirmed CNS involvement. Her condition improved with continued antifungal. Not candidate for amphotericin B.

Discussion: This case highlights the difficulty in diagnosing coccidioidomycosis, which is often mistaken for other conditions. The patient's initial misdiagnosis of lymphoma while undergoing care in Mexico led to a delay in appropriate treatment. Initially, treatment focused on a superimposed skin infection, assuming the underlying cause was NHL. However, even after diagnosing pulmonary coccidioidomycosis, the misdiagnosis of NHL persisted until a repeat skin biopsy ruled it out. This case highlights the challenge of differentiating reactive inflammatory changes from malignancy, which can delay a definitive diagnosis. The diagnosis was eventually confirmed through lymph node biopsy and subsequent serology testing, the most appropriate diagnostic methods. The initial treatment with fluconazole was appropriate as azoles remain the gold standard for therapy. The case underscores the need for timely and accurate diagnosis to initiate appropriate antifungal therapy and prevent complications.