Differential Diagnosis for Fungus Infection with Ulcer on Skin and Purple Patches

• Single most likely diagnosis:
  • Chromoblastomycosis: This is a fungal infection of the skin caused by various species of fungi, including Fonsecaea, Phialophora, and Cladophialophora. It typically presents with ulcerative lesions and purple patches, making it a strong candidate for the described symptoms.
• Other Likely diagnoses:
  • Sporotrichosis: This fungal infection, caused by Sporothrix schenckii, can lead to skin ulcers and lesions, sometimes with a purple discoloration, especially in its fixed cutaneous form.
  • Eumycetoma: A chronic granulomatous infection of the skin and subcutaneous tissue caused by various fungi, which can present with ulcers, sinuses, and purple patches.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Mucormycosis: Although less common and typically associated with more severe, life-threatening infections, mucormycosis can cause skin lesions and ulcers, especially in immunocompromised patients. Its rapid progression and high mortality rate make it crucial not to miss.
  • Histoplasmosis: In rare cases, histoplasmosis can cause skin lesions, including ulcers, particularly in immunocompromised individuals. Given its potential severity, it should not be overlooked.
• Rare diagnoses:
  • Phaeohyphomycosis: A rare fungal infection caused by dematiaceous fungi, which can lead to skin lesions, including ulcers and purple patches, though it is less common than other diagnoses listed here.
  • Lobomycosis (Jorge Lobo's disease): A rare, chronic fungal infection of the skin caused by Lacazia loboi, characterized by keloid-like lesions and, in some cases, ulcers and discoloration, including purple patches. It is endemic to certain regions of Central and South America.