ICD-10 Code B36.3 – Black piedra (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B36.3 – Black piedra
What it is
B36.3 identifies black piedra, a superficial fungal infection of the hair shaft. It usually affects scalp hair and causes hard, dark nodules attached to the hair.
Clinical signs
Look for firm black to brown concretions on hair shafts, often with a rough or gritty feel. Clinical features vary; refer to documentation, and confirm the diagnosis when the appearance matches black piedra.
When to use this code
Use B36.3 when the provider documents black piedra or describes a fungal infection of hair shafts consistent with this condition. Use it for confirmed cases involving scalp or other hair-bearing areas, not for nonspecific hair breakage or dandruff.
Do not use for
Do not use this code for white piedra, tinea capitis, or simple debris on the hair. If the record does not clearly identify black piedra, check documentation before coding.
Coding tip
Assign B36.3 only when the note names black piedra or clearly describes the classic hair-shaft nodules.