tinea versicolor tinea nigra white Piedra and Black Piedra

Superficial mycoses are fungal infections limited to the stratum corneum and its adnexal structures. The most frequent types are dermatophytoses or tineas. Tinea versicolor involves the skin in the form of hypochromic or hyperchromic plaques, and tinea nigra affects the skin of the palms with dark plaques. White Piedra and Black Piedra are parasitic infections of scalp hairs in the form of concretions caused by fungal growth. Diagnosis of these mycoses is made from mycologic studies, direct examination, stains, and isolation, and identification of the fungi. Treatment includes systemic antifungals, topical antifungals, and keratolytics.

tinea versicolor tinea nigra white Piedra and Black Piedra

Superficial mycoses are fungal infections limited to the stratum corneum and its adnexal structures. The most frequent types are dermatophytoses or tineas. Tinea versicolor involves the skin in the form of hypochromic or hyperchromic plaques, and tinea nigra affects the skin of the palms with dark plaques. White Piedra and Black Piedra are parasitic infections of scalp hairs in the form of concretions caused by fungal growth. Diagnosis of these mycoses is made from mycologic studies, direct examination, stains, and isolation, and identification of the fungi. Treatment includes systemic antifungals, topical antifungals, and keratolytics.

ultrastructure of Black Piedra

Summary. Black Piedra or nodular tricho-mycosis is a superficial mycosis of the hair shaft, prevalent in the tropical areas of South America and Asia and caused by the fungus Piedraia hortai. By scanning electron microscopy the invasion of the hair keratin and the elimination of spores through canals was seen. Transmission electron microscopy showed a complex, well-organized microsystem, in which cement-producing hyphae constitute the pseudoparenchyma. Both sexual and asexual reproduction were found. Sexual reproduction gives rise to ascospores and asexual reproduction to arthrospores. The ascospores were found in thick-walled bags, the asci; the arthrospores, that undergo gemmation, are eliminated through canals, disseminating the disease.

Zusammenfassung. Die schwarze Piedra, Piedra nigra oder nodulare Trichomykose ist eine oberflachliche Mykose des Haarschaftes, die in den tropischen Gebieten Sudamerikas und Asiens vorkommt. Der Erreger ist Piedraia hortai. Die rasterelektronenmikroskopische Untersuchung belegt die Invasion des Haarkeratins und die Freisetzung von Sporen an der Knotchenober-flache. Transmissionselektronenmikroskopisch lies sich ein komplexes, gut organisiertes Mikro-system darstellen: Eine vom Pilz sezernierte Kittsubstanz zementiert die Hyphen zu einem Pseudoparenchym zusammen. Sexuelle und asexuelle Reproduktion tritt nebeneinander auf. Die sexuelle Vermehrung fuhrt zur Askosporenbildung, die asexuelle zur Arthrosporenbildung. Die Askosporen finden sich in dickwandigen, sackformigen Asci. Arthrosporen sind zur Gemmenbildung befahigt und verbreiten die Infektion durch ihre Streuung.