Almeida Hiram Larangeira de, Assis Thales de Moura, Faria Eduardo Camargo, Gimenes Viviane Mazo Fávero
Postgraduate Studies in Health and Behavior, Department of Dermatology, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
Postgraduate Studies in Health and Behavior, Universidade Católica de Pelotas, Pelotas, RS, Brazil.
An Bras Dermatol. 2025 Jul-Aug;100(4):501140. doi: 10.1016/j.abd.2025.501140. Epub 2025 Jul 3.
White piedra is a disease caused by some species of the genus Trichosporon. A case of white piedra was investigated, whose molecular examination identified Cutaneotrichosporon (Trichosporon) debeurmannianum as the causative agent.
Scanning electron microscopy (SEM) was used to examine the affected hairs, as well as the fungal colony of C. debeurmannianum obtained from the hairs. For comparative purposes, a colony of Trichosporon mucoides obtained from a mycotheque was also examined.
Examination of the affected hairs using SEM easily demonstrates nodules on the hair shaft with a predominance of rounded yeast-like structures, adhered to each other by a cementing substance. Examination of the C. debeurmannianum colony demonstrates significant adhesion between the fungal cells by a reticular extracellular matrix. Examination of the T. mucoides colony obtained from a mycotheque demonstrates a small production of fibrillar substance between the blastoconidia.
Examination of the colony obtained from the piedra showed significant formation of extracellular matrix, adhering to and covering the fungal structures, forming a biofilm. This matrix must correspond to the cementing substance described in the condition.
The synthesis of the extracellular matrix must be crucial in the formation of white piedra nodules.
白癣是由毛孢子菌属的某些菌种引起的一种疾病。对一例白癣病例进行了调查，其分子检测确定皮状毛孢子菌（毛孢子菌）德布尔曼尼氏菌为病原体。
使用扫描电子显微镜（SEM）检查受影响的毛发以及从毛发中分离得到的德布尔曼尼氏菌的真菌菌落。为作比较，还检查了从真菌保藏库获得的粘液毛孢子菌的菌落。
使用SEM检查受影响的毛发很容易发现毛干上有结节，主要是圆形的酵母样结构，通过一种粘结物质相互粘附。对德布尔曼尼氏菌菌落的检查表明，真菌细胞之间通过网状细胞外基质有显著的粘附。对从真菌保藏库获得的粘液毛孢子菌菌落的检查表明，在芽生孢子之间有少量的纤维状物质产生。
对从白癣中获得的菌落的检查表明，细胞外基质大量形成，附着并覆盖真菌结构，形成生物膜。这种基质必定与该病症中描述的粘结物质相对应。
细胞外基质的合成在白癣结节的形成中必定至关重要。
