Pigmented broken hairs at scalp level, often indicating active follicular damage or breakage.
Black dots are remnants of broken hairs visible at the scalp surface on trichoscopy. They can be seen in active alopecia areata, tinea capitis, trichotillomania and other causes of hair breakage. Their significance depends on the clinical pattern and associated signs. In a smooth patch with exclamation mark hairs, black dots support alopecia areata; in a scaly inflamed patch in a child, fungal infection becomes more likely. They are a clue, not a complete diagnosis.
DermNet trichoscopy: https://dermnetnz.org/topics/trichoscopy ; DermNet hair loss: https://dermnetnz.org/topics/hair-loss