Hypotrichotic nevus (congenital triangular alopecia).

Abstract

A 9-year-old boy was first observed due
to alopecia areata at the nape. However, his mother said
that the alopecic area had been present from the first
period of life and had not changed substantially over
time, despite the many topical therapies made. The family
history was negative for alopecia areata and other
autoimmune diseases. His family and personal history
was negative for atopy.
The physical examination highlighted at the back
hair line a round area of about 2 cm, apparently devoid
of hair (Fig. 1). At closer observation thin and less pigmented
hair (Fig. 2) could be observed.
The dermoscopic observation (Fig. 3) confirmed the
clinical finding showing also the absence of pseudocomedos,
of "cadaverized" and exclamation mark hairs
and thus leading to the final diagnosis of hypotrichotic
nevus.