Epidemiology and prognosis of subungual melanoma in 34 Japanese patients

Abstract

The incidence of malignant melanoma is much lower in the Japanese than in caucasians. However, amongst the various types of malignant melanoma, the subungual and periungual sites are commonly found in the Japanese. One hundred and fifty-one cases of cutaneous malignant melanoma were seen over a 25-year period at our hospital. We found that, in 34 patients (23%), the subungual region was involved, a high frequency for one institution. We have analysed these patients and looked at their treatment. The finger nails were affected in 21 cases (62%) and the toe nails in 13 cases (38%). The thumb nails or great toe nails were affected in 25 of the 34 patients (73%). In 25 patients, histopathological features of acral lentiginous melanoma were found, with four cases of superficial spreading melanoma and five of nodular amelanotic melanoma. Of the latter group, four mimicked fibrous histiocytic tumour, and one was a desmoplastic malignant melanoma. The proportion of patients presenting with stage III disease decreased after 1982, with a corresponding increase in patients whose tumour thickness was less than 4 mm (stage II). Concurrently, the prognosis for subungual malignant melanoma improved. The 5-year survival rate in each of the periods 1969-82 and 1983-93 was 53 and 87%, respectively. This is similar to that found in plantar malignant melanoma and is felt to be due to a greater public awareness of the condition and to the introduction of effective chemotherapy (the DTIC-AC nitrosurea-vincristine (DAV) regimen). Although the frequency of malignant melanoma is rather low in the Japanese, our data indicate that there is a high incidence of subungual malignant melanoma. Public awareness of the early stage of malignant melanoma seems to have improved prognosis.

Concomitant traumas influence prognosis in melanomas of the nail apparatus*

“…1,4,13,18,19 Comparing the characteristics of our group of patients with other studies, age and gender distributions agreed largely with those reported previously in NAM. 2,13,19,20 In agreement with other literature, the most frequent primary clinical signs that were observed by our patients were nail and/or periungual pigmentations (longitudinal melanonychia, Hutchinson sign). 18 Nail and periungual pigmentation is not specific for NAM but can be observed regularly in early and advanced stages, sometimes many years before establishment of a mass that led to making the diagnosis.…”

“…[21][22][23] As expected, we found acrolentiginous melanoma to be the most frequent histological type. 3,13,19,20 In our study, mean ± SD TT of the melanomas (3AE95 ± 2AE58 mm) and a high rate of ulcerated tumours were within the range of the data reported elsewhere, 13,19,20 indicating late recognition, diagnosis and treatment in comparison with other melanomas of the skin. It can be assumed that late diagnosis per se might be responsible for the unfavourable prognosis rather than the specific tumour location.…”

Primary Malignant Tumors of the Nail Unit

“…125 In a small series, systemic treatment with dacarbazine, vincristine, and nitrosourea was credited with improving prognosis. 102 Overall, the prognosis in cases of melanoma of the nail unit is poor, although there are trends to show that this is improving, namely from earlier diagnosis and more in situ and superficial tumors. Surgical extirpation remains a challenge.…”

“…A study of nail unit melanomas in Japanese patients compared survival rates in the periods 1969-1982 and 1983-1993. 102 The 5-year survival rates increased from 53% to 87%, respectively. The authors credited this dramatic progress to greater public awareness (and discovery of thinner melanomas) and to the introduction of improved chemotherapy.…”

Desmoplastic Melanoma of the Nail

“…2,4 Prognosis in nail melanoma is related to tumor depth 1-3 and biological grade 2 but not to histological type. 3 One of the greatest difficulties is delayed diagnosis related to correct clinical and, sometimes, histological identification.…”