Case #12:

Clinical Presentation:
A 35-year-old man with AIDS complains of painless oral ulcers (Case 12 Image 1)

Clinical Diagnoses:
Primary Syphilis
Oral Fusospirochetosis
Oral Histoplasmosis
Viral Oral Lesion (eg Herpes Simplex, CMV)

Case 12 Image 2: scraping of oral lesion demonstrating ovoid yeasts of the dimorphic fungus Histoplasma capsulatum within macrophage cytoplasm.
Case 12 Image 3: peripheral blood smear demonstrating phagocytosized yeasts within a polymorphonuclear leucoctye.
Case 12 Image 4: Silver-staining of a liver biopsy showing clusters of ovoid budding yeast forms of Histoplasma.

Discussion:
Microbiologic Diagnosis:
Histoplasmosis
Present as a mold in soil and as a yeast in tissue, H capsulatum can cause a severe, disseminated systemic mycosis in immunocompromised persons. Inhalation of spores transmits this infection. It is endemic to the central and eastern US. Bats can be infected and pass the organism in their guano.