To the Editor:
An 85-year-old man with a history of hypertension and chronic kidney disease presented with a localized darkening patch of hair on the left parietal scalp that had progressed over the last 7 years (Figure 1A). He had no prior history of skin cancer. Physical examination revealed the remainder of the hair was gray. There was an irregularly pigmented plaque on the skin underlying the darkened hair measuring 5.0 cm in diameter that was confirmed to be melanoma (Figure 1B). He underwent a staged excision to remove the lesion. The surgical defect was closed via a 5.0×6.0-cm full-thickness skin graft.
FIGURE 1. A, Localized darkening of hair on the left parietal scalp. B, An irregularly pigmented plaque measuring 5.0 cm in diameter was noted underlying the darkened hair.
The initial biopsy showed melanoma in situ. However, the final pathology report following the excision revealed an invasive melanoma with a Breslow depth of 1.0 mm (Clark level IV; American Joint Committee on Cancer T1b).1 Histopathology showed pigment deposition with surrounding deep follicular extension of melanoma (Figure 2).
FIGURE 2. Staged excision of the pigmented area of the left parietal scalp revealed an emerging hair shaft with dark, variably chunky pigment deposition seen in association with surrounding melanoma (H&E, original magnification ×100).
The patient declined a sentinel lymph node biopsy and agreed to a genetic profile assessment.2 The results of the test identified the patient had a low probability of a positive sentinel lymph node and the lowest risk of melanoma recurrence within 5 years. The patient was clear of disease at 12-month follow-up.
Based on a PubMed search of articles indexed for MEDLINE using the terms hair repigmentation and melanoma, there have been 11 other reported cases of hair repigmentation associated with melanoma (Table).3-13 It initially was suspected that this rare phenomenon primarily existed in the female population, as the first 5 cases were reported solely in females,3-7 possibly due to the prevalence of androgenetic alopecia in males.11 However, 6 cases of repigmentation associated with melanoma were later reported in males8-13; our patient represents an additional reported case in a male. It is unknown if there is a higher prevalence of this phenomenon among males or females.
Most previously reported cases of repigmentation were associated with melanoma in situ, lentigo maligna type. Repigmentation also has been reported in malignant melanoma, as documented in our patient, as well as desmoplastic and amelanotic melanoma.5,6 In every case, the color of the repigmentation was darker than the rest of the patient’s hair; however, the repigmentation color can be different from the patient’s original hair color from their youth.4,5,11
The exact mechanism responsible for hair repigmentation in the setting of melanoma is unclear. It has been speculated from prior cases that repigmentation may be caused by paracrine stimulation from melanoma cells activating adjacent benign hair follicle melanocytes to produce melanin.7,14,15 This process likely is due to cytokines or growth factors, such as c-kit ligand.14,15 Several neural and immune networks and mediators activate the receptor tyrosine kinase KIT, which is thought to play a role in activating melanogenesis within the hair bulb.14 These signals also could originate from changes in the microenvironment instead of the melanoma cells themselves.6 Another possible mechanism is that repigmentation was caused by melanin-producing malignant melanocytes.4
Because this phenomenon typically occurs in older patients, the cause of repigmentation also could be related to chronic sun damage, which may result in upregulation of stem cell factor and α-melanocyte–stimulating hormone, as well as other molecules associated with melanogenesis, such as c-KIT receptor and tyrosinase.15,16 Upregulation of these molecules can lead to an increased number of melanocytes within the hair bulb. In addition, UVA and narrowband UVB have been recognized as major players in melanocyte stimulation. Phototherapy with UVA or narrowband UVB has been used for repigmentation in vitiligo patients.17