A rapidly growing pigmented nail streak resulting in diffuse melanosis of the nail. A possible sign of subungual melanomain situ

Abstract

Subungual melanomas are one of the most common types of malignant melanoma among the Japanese population. Although most pigmented nail streaks are benign and remain unchanged in their color and shape for a long time, rarely are they precursor lesions of subungual melanomas, i.e., a rapid growing pigmented nail streak resulting in diffuse melanosis of the nail is thought to be an early stage of subungual melanoma in situ. We found four patients with these changes; three of these patients were children. The lesions occurred on the right index finger, right thumb, left middle finger, and right great toe, respectively. A slightly haphazard combination of colors ranging from dark brown to black, the important characteristic of subungual melanoma in situ, was observed in two cases. In the remaining two cases, although the haphazard combination of colors was not distinctive, many fine, dark, longitudinal lines were seen within diffuse, light-brownish pigmentation. Serial histologic examination of the excised tissue specimens showed great proliferation of vacuolated melanocytes with variable nuclear atypicality along the entire basal layer in all cases. These histologic changes were compatible with those of atypical melanocytic hyperplasia or intraepidermal melanoma (in situ melanoma), which is an early lesion of subungual melanoma. An adult case is thought to be a definite example of a subungual melanoma in situ. We also made the diagnosis of melanoma in situ in the remaining three cases of children with rapidly growing pigmented nail streaks because their histopathologic features were distinguishable from those of the adult case. However, there remains some hesitation about this because invasive subungual melanoma is rare in children. Cancer 64:2191-2197, 1989. ACIAL DIFFERENCES are pronounced in the inci-R dence and predilection of melanoma types. Malignant melanoma occurs much less frequently among Jap-anese individuals than among white individuals, and melanoma occurring in the acral regions including the subungual position is the most common type of mela-noma among the Japanese population.' Reflecting its predilection, there have been several case reports of the acral type of melanoma in situ in the Japanese litera-t ~ r e , ~-~ including one report of subungual melanoma in sir^.^ However, only one case report has been published about palmar melanoma in situ in a white woman.6 Currently , however, in all of the instances a sharp demarcation cannot be made between atypical melanocytic hyperplasia (melanocytic dysplasia) and in situ

Nail Melanoma in Children: Differential Diagnosis and Management

“…Six cases were diagnosed as melanoma in situ (Kato et al, 7 Hori et al, 6 Kiryu, 9 and Antonovich et al 10 ). Three of these six (Kato 7 ) have been criticized by some authors 4 who believed they should have been diagnosed as benign melanocytic hyperplasia even if the histopathology showed nuclear atypia and melanocytic transepidermal migration. Even the case of Kiryu 9 has been criticized 4 and possibly considered a highly active junctional nevus.…”

“…In children nail melanoma is very rare, and melanonychia is generally due to nail matrix nevi (benign melanocytic hyperplasia) 3,4 . To our knowledge, until now only eight cases have been reported in the literature 5–10 . We report two additional cases and discuss the histopathology, differential diagnosis, and management.…”

Paediatric melanoma of the nail unit with rapid progression: a case report with dermatoscopic follow‐up and intraoperative dermatoscopic images

“…Previous reported cases of paediatric nail unit melanoma have been considered by some authors as atypical but probably representing benign lentiginous melanocytic hyperplasia or highly active junctional naevi rather than melanoma . Subsequently, other reports described acral melanomas in children after supportive evidence by immunohistochemical staining (p16, S‐100, HMB‐45).…”

Malignant Melanoma In situ Arising in the Nail Unit of a Child

“…However, there are no proven cases of such malignant melanomas arising in children reported so far, except for a few probable cases (6,7). In this report, a patient that is considered clinically and histopathologically to be a very rare case of malignant melanoma in situ arising in the nail unit of a child is presented, and the significance of the early diagnosis is discussed.…”