Black piedra

This code represents black piedra, a superficial fungal infection of the hair shaft caused by Piedraia hortae. It is characterized by the formation of hard, dark, gritty nodules firmly attached to the hair, typically affecting the scalp hair but can also occur on facial or body hair. The infection does not invade the hair follicle or cause inflammation of the scalp.

Assign this code when documentation confirms a diagnosis of black piedra based on clinical examination and/or microscopic identification of Piedraia hortae. This code is appropriate for reporting the presence of the fungal infection itself, regardless of the treatment modality.

• Differentiate from white piedra (Tinea nodosa), which is caused by Trichosporon species and coded elsewhere.
• Do not use for other superficial fungal infections of the hair, such as tinea capitis, which involve the hair follicle and surrounding skin.
• Ensure the documentation specifies "black piedra" or clearly describes the characteristic hard, dark nodules on the hair shaft.