A 32-year-old HIV-infected man from Manipur with a CD4 count of 50 cells per microlitre presents with fever, weight loss, hepatosplenomegaly and diffuse papular skin lesions resembling molluscum contagiosum. Bone marrow smear shows intracellular and extracellular round yeast-like cells 3 to 8 micrometres across, some showing a central transverse septum. Which organism is responsible?

• A Histoplasma capsulatum var capsulatum
• B Leishmania donovani
• C Talaromyces marneffei ✓
• D Cryptococcus neoformans var grubii

Explanation

Talaromyces marneffei, formerly Penicillium marneffei, is a dimorphic fungus endemic to Southeast Asia including Northeast India. In tissue it is the only thermally dimorphic fungus that divides by fission, producing the characteristic central transverse septum seen in the bone marrow smear, and it causes disseminated disease with molluscum-like skin lesions in advanced AIDS. Histoplasma divides by budding and lacks the septum, Leishmania amastigotes contain a kinetoplast and nucleus rather than a septum, and Cryptococcus is encapsulated and extracellular.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.