Fungal Differential Diagnosis

The patient's symptoms and laboratory results suggest a fungal infection. Here's a differential diagnosis based on the provided information:

• Single most likely diagnosis
  • Coccidioides immitis/posadasii: The patient's occupation in a cotton mill, exposure to soil from the southwestern US, and the presence of alternating, barrel-shaped arthroconidia in the sputum culture are highly suggestive of coccidioidomycosis. The patient's symptoms, such as fever, chills, weight loss, and anorexia, are also consistent with this diagnosis.
• Other Likely diagnoses
  • Blastomyces dermatitidis: Although less likely, blastomycosis is a possible diagnosis given the patient's symptoms and the fact that the fungus was described as a whitish mold. However, the microscopic examination of the arthroconidia is more characteristic of Coccidioides.
  • Histoplasma capsulatum: Histoplasmosis is another possibility, but the lack of exposure to bird or bat droppings and the microscopic characteristics of the fungus make it less likely.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Cryptococcosis: Although the patient's CSF examination was unremarkable, cryptococcosis can be a life-threatening infection, especially in immunocompromised patients. It's essential to consider this diagnosis, especially given the patient's diabetes mellitus.
  • Mucormycosis: This rare but deadly infection can occur in patients with diabetes mellitus, particularly those with poor glucose control. Although the patient's symptoms and laboratory results do not strongly suggest mucormycosis, it's crucial to consider this diagnosis due to its high mortality rate.
• Rare diagnoses
  • Sporothrix schenckii: Sporotrichosis is a rare fungal infection that typically affects the skin. Although it's unlikely given the patient's symptoms and laboratory results, it's essential to consider this diagnosis, especially if the patient has a history of skin trauma or exposure to contaminated soil.
  • Paracoccidioides brasiliensis: Paracoccidioidomycosis is a rare fungal infection that primarily affects the lungs. Although the patient's symptoms and laboratory results do not strongly suggest this diagnosis, it's essential to consider it, especially if the patient has traveled to or has connections to South America.