Morphology and Descriptions of Endemic Fungal Infections with Yeasts in Tissues Broad-based budding yeasts: • Description: Broad-based budding yeasts (10-15 microns in size) • Consistent with Blastomyces dermatitidis, however endospores of Coccidioides spp, Candida spp, Histoplasma, Cryptococcus, and Aspergillus conidia can be confused histologically Narrow-based budding yeasts with mucicarmine positive capsule: • Description: Narrow-based budding yeasts (4-10 microns in size) with thick mucicarmine positive capsule and positive with melanin stains (Fontana Masson) • Consistent with Cryptococcus spp; however Candida spp and Histoplasma can be confused histologically Small yeasts with narrow based budding: • Description: small yeasts (2-4 microns in size) with narrow based budding grouped in clusters inside macrophages • Consistent with Histoplasma capsulatum however small variant of B. dermatitidis, capsule deficient Cryptococcus, endospores of Coccidioides spp, Pneumocystisjirovecii, Penicillium marneffei, Candida glabrata can be confused histologically. Spherules with multiple endospores: • Description: spherules with multiple endospores (10-100 microns in size) • Consistent with Coccidioides spp; however Blastomyces, Histoplasma, Candida, Pneumocystis, and other yeasts can be confused histologically when no spherules are present In addition, Rhinosporidium seeberi has sporangia with endospores which are larger Dr. Sara Dong @swinndong #endemic #fungal #infections #morphology #yeasts #pathology #clinical #atlas #fungi #microbiology #differential #diagnosis
