A 40-year-old man develops erythema nodosum, conjunctivitis, and a pleural effusion. Over several weeks, pulmonary lesions lead to cavitation and a large, thin-walled cavity. He was traveling in Arizona before becoming ill. Sputum samples reveal mature spherules. Which of the following is the most likely diagnosis?
**Core Concept**
Erythema nodosum, conjunctivitis, and pleural effusion are symptoms that can be associated with various infectious and inflammatory conditions. In this case, the presence of mature spherules in sputum samples and the clinical presentation of cavitation in the lungs points towards a specific fungal infection.
**Why the Correct Answer is Right**
The patient's symptoms and the presence of mature spherules in sputum samples are characteristic of coccidioidomycosis, a fungal infection caused by *Coccidioides immitis* or *Coccidioides posadasii*. These fungi are endemic to the southwestern United States, including Arizona, and can cause a range of symptoms, from mild respiratory illness to severe pulmonary disease. The mature spherules are a hallmark of this infection and can be identified in sputum samples or tissue specimens. The presence of erythema nodosum, conjunctivitis, and pleural effusion in this patient suggests a disseminated infection.
**Why Each Wrong Option is Incorrect**
**Option A:** Histoplasmosis is another fungal infection that can cause pulmonary disease, but it is typically associated with exposure to bird or bat droppings, and the presence of mature spherules is not characteristic of this infection.
**Option B:** Blastomycosis is a fungal infection caused by *Blastomyces dermatitidis*, but it typically presents with skin lesions and lung disease, and the presence of mature spherules is not a diagnostic feature.
**Option C:** Aspergillosis is a fungal infection caused by *Aspergillus* species, but it typically presents with allergic bronchopulmonary aspergillosis or invasive aspergillosis in immunocompromised patients, and the presence of mature spherules is not characteristic of this infection.
**Clinical Pearl / High-Yield Fact**
Coccidioidomycosis is a fungal infection that can cause severe pulmonary disease, particularly in immunocompromised patients. The presence of mature spherules in sputum samples or tissue specimens is a diagnostic hallmark of this infection. Travel history to endemic areas, such as Arizona, can increase the risk of exposure to this fungus.
**Correct Answer: C. Coccidioidomycosis**