Longitudinal melanonychia caused by trichophyton rubrum. Histochemical and ultrastructural study of two cases.
Two patients had black pigmentation affecting a great toenail that clinically simulated longitudinal melanonychia; Trichophyton rubrum with a diffusible black pigment was consistently isolated from the nail lesions. Light microscopic examination of nail samples stained with hematoxylin-eosin-safranine showed hyphae containing a brown cytoplasmic pigment. The positive Masson-Fontana stain suggested that the pigment was related to melanin. Both histologic and ultrastructural studies demonstrated intracytoplasmic polymerization, a method of final enzymatic polymerization that is unusual for melanin-producing fungal strains.
Department of Pathology, Centre Hospitalier et Universitaire, Nice, France.
C
C
Perrin
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R
Baran
D000328:Adult; D000368:Aged; D005260:Female; D005533:Foot Dermatoses / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D008543:Melanins / Q000096:biosynthesis*; D008854:Microscopy, Electron; D009262:Nails / Q000382:microbiology* / Q000473:pathology*; D014009:Onychomycosis / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology*; D010858:Pigmentation; D014249:Trichophyton / Q000302:isolation & purification / Q000378:metabolism*
D008543:Melanins