Poliosis in a scalp nodule. Congenital intradermal nevus with poliosis

Poliosis Circumscripta Associated with Neurofibroma

“…In those cases, they suggested that the pathogenesis of the poliosis might involve a cytotoxic T‐cell‐mediated autoimmune response to the melanocytes located around the matrices of the hair follicles (5, 7). Walker et al(5) also reported one case of poliosis circumscripta associated with a congenital melanocytic nevus, and Mendez et al(2) reported a similar case. It was postulated that fetal melanocytes might have failed to migrate from the neural crest into the hair bulbs but had instead proliferated in the perifollicular dermis to form a congenital intradermal nevus around non‐pigmented hairs (2).…”

“…Walker et al(5) also reported one case of poliosis circumscripta associated with a congenital melanocytic nevus, and Mendez et al(2) reported a similar case. It was postulated that fetal melanocytes might have failed to migrate from the neural crest into the hair bulbs but had instead proliferated in the perifollicular dermis to form a congenital intradermal nevus around non‐pigmented hairs (2). Dunn et al(8) reported a case of melanoma of the scalp presenting as poliosis circumscripta.…”

Poliosis circumscripta in the acquired intradermal nevus on the scalp: a brief review on the pathogenesis of this phenomenon

“…Poliosis circumscripta is a localized patch of white to gray hair associated with many benign and malignant dermatologic disorders. This condition has been described in patients with congenital melanocytic nevus, 1–5 but there have been only a few case reports of poliosis in patients with acquired melanocytic nevus. We describe a patient with acquired intradermal nevus who developed poliosis circumscripta and briefly review the pathogenesis of this phenomenon.…”

“…Poliosis may also arise embryogenetically 2 . According to this hypothesis, fetal melanocytes that fail to migrate from the neural crest into the hair bulbs may proliferate into the perifollicular area, forming a congenital melanocytic nevus with non‐pigmented hair, a pathogenic pathway that may occur in patients with poliosis with congenital melanocytic nevi 2,3 .…”

“…According to this hypothesis, fetal melanocytes that fail to migrate from the neural crest into the hair bulbs may proliferate into the perifollicular area, forming a congenital melanocytic nevus with non‐pigmented hair, a pathogenic pathway that may occur in patients with poliosis with congenital melanocytic nevi 2,3 . In these patients, the adjacent skin may show normal pigmentation and an absence of inflammatory infiltration, 2–5 features differentiating between poliosis in congenital melanocytic nevi and poliosis in acquired melanocytic nevi. There was no exact indication of the duration of poliosis, but poliosis was not fully regressed in the reported cases associated with congenital melanocytic nevi 3,4 .…”