T. Stewart1,2, I. Pye2, M. Whitfeld1,2,3
The pathogenesis of hair greying remains poorly understood. A close interaction between the nervous system and melanocytes has long been suspected based on their shared embryologic origin and involvement in conditions such as segmental and follicular vitiligo. Confocal microscopic analysis and electron microscopy has shown cutaneous nerve endings in close proximity with melanocytes, similar to synaptic contacts in neural tissue. Further, melanocyte synthesis rates are altered by neuropeptides (e.g. substance P) secreted by these afferent nerve endings.1,2 Surgical sympathectomy has resulted in segmental alterations in hair pigmentation and spontaneous repigmentation has been seen with various neuropathies.3,4 We present three patients with asymmetric hair greying. Two displayed altered hair pigmentation on the anterior trunk with sharp demarcation at the midline. The third exhibited three distinct hair colour tones producing a checkerboardlike appearance. There was no premature greying nor any neurological signs present. This small case series provides insights into possible contributing factors in the pathogenesis of hair greying.
1. Innervation of melanocytes in human skin. The Journal of Experimental Medicine. 1996;184(4):1385–1395.
2. Mukuno K, Witmer R. Innervation of melanocytes in humaniris; An electron microscopic study. Albrecht Von Graefes Arch Klin Exp Ophthalmol. 1977;203(1):1–8.
3. Ortonne JP, Thivolet J, Guillet R. Graying of hair with age andsympathectomy. Arch Dermatol.1982;118(11):876–877.
4. Adiga GU, Rehman KL, Weirnick PH. Permanent localized hairrepigmentation following herpes zoster infection. Arch Dermatol.2010;146(5):569–570.