Plantar malignant melanoma. Statistical and clinicopathological studies

Medial Plantar Fasciocutaneous Flap Reconstruction for Load-Bearing Foot Defects in Patients With Acral Melanoma

BACKGROUND

Acral lentiginous melanoma (ALM) is a rare subtype of malignant melanoma that usually involves the weight-bearing plantar area. Plantar defect reconstruction has traditionally been performed with skin grafts or free flaps. This study examined the efficacy and safety of a medial plantar artery perforator flap (MPAPF) for plantar defect reconstruction after wide excision of an ALM.

METHOD

Twenty-five patients who underwent reconstruction with a MPAPF between 2011 and 2021 were enrolled in this study. The defects were classified into 6 plantar zones. Demographic and clinical data were retrospectively analyzed.

RESULTS

Reconstruction with medial plantar fasciocutaneous island flaps was performed in all cases, except for 4 patients who had lesions in forefoot, which required free medial plantar flaps. Defects in lateral and posterior heel were more likely to present with venous congestion and require longer healing times and revision surgery (P < 0.05). The average follow-up period was 49 months. Four and 5 patients developed local recurrence and distant metastasis, respectively. Four cases of hyperkeratosis and paresthesia were documented, but there were no cases of ulceration or wound dehiscence. None of the cases required secondary debulking procedures.

CONCLUSIONS

The MPAPF is safe and effective for plantar defect reconstruction among patients with ALM. Meticulous dissection and adequate tunneling are needed, particularly for defects in the lateral and posterior heel, to minimize flap congestion and revision operations.

PTEN Promoter Hypermethylation Is Associated with Breslow Thickness in Acral Melanoma on the Heel, Forefoot, and Hallux

Background

Acral melanoma occurs on glabrous skin or the nail apparatus and is distinct from ultraviolet-related melanoma due to differing genetic alteration patterns. Although the pathogenesis of acral melanoma is not well understood, mechanical stress is thought to induce acral melanoma. The incidence of gene mutation and promoter methylation has been reported in tumors from acral melanoma; however, an association between genetic/epigenetic alterations and mechanical stress in acral melanoma remains unclear.

Objective

To investigate the relationship between clinical/genetic factors and mechanical stress in acral melanoma.

Methods

A retrospective review of 52 patients diagnosed with acral melanoma was performed. We reviewed the clinical characteristics of patients, tumor status, and tumor location. Mutations in BRAF, NRAS, and the TERT promoter, along with KIT amplification and PTEN promoter methylation were analyzed in the tumors.

Results

The heel (34/52, 65.4%) was the most common anatomical tumor site. Mutations in BRAF (6/48, 12.5%), NRAS (6/49, 12.2%), and the TERT promoter (4/33, 12.1%), along with KIT amplification (3/37, 8.1%) and PTEN promoter hypermethylation (12/48, 25.0%) were observed in the tumors. On the forefoot, heel, and hallux, PTEN promoter hypermethylation was significantly associated with Breslow thickness (p=0.001) and ulceration rate (p=0.042). On the midfoot and lesser toes, there was no significant difference in Breslow thickness or ulceration rate regardless of PTEN promoter hypermethylation (p>0.05).

Conclusion

PTEN promoter hypermethylation is associated with Breslow thickness and tumor ulceration on the forefoot, heel, and hallux in acral melanoma in Korean patients.

Translational pathology, genomics and the development of systemic therapies for acral melanoma

Acral melanomas arise on the non-hair bearing skin of the palms, soles and in the nail beds. These rare tumors comprise 2-3 % of all melanomas, are not linked to UV-exposure, and represent the most frequent subtype of melanomas in patients of Asian, African and Hispanic origin. Although recent work has revealed candidate molecular events that underlie acral melanoma development, this knowledge is not yet been translated into efficacious local, regional, or systemic therapies. In the current review, we describe the clinical characteristics of acral melanoma and outline the genetic basis of acral melanoma development. Further discussion is given to the current status of systemic therapy for acral melanoma with a focus on ongoing developments in both immunotherapy and targeted therapy for the treatment of advanced disease.

A clinicopathological analysis of 153 acral melanomas and the relevance of mechanical stress

The pathogenesis of melanomas emerging in plantar surfaces remains unclear; however, mechanical stress has been reported to increase the formation of melanomas. In this study, we conducted a multicenter retrospective analysis of 153 acral melanomas diagnosed between 2000 and 2015 in Taiwan. The male-to-female ratio of the patients in question was 1:1.28, and the mean age at diagnosis was 68 years. We examined whether melanomas which developed in different areas of the patients' soles differed in their associations with various clinicopathological characteristics and survival. Testing by goodness of fit indicated that stress-bearing areas were significantly more conducive to the generation of melanomas than non-stress-bearing areas (P < 0.0001). More specifically, compared to the arch, the rear of the foot and front of the foot were significantly more conducive to the generation of melanomas (P < 0.0001 and P < 0.0001, respectively). The distribution pattern was not associated with differences in age, gender, right/left foot involvement, ulceration, mitosis, lymph node metastasis, tumor thickness, or stage. The overall, distant metastasis-free, and recurrence-free survival rates did not differ significantly between the stress-bearing and non-stress-bearing areas. Furthermore, while acral melanomas tended to develop on stress-bearing areas, the distribution pattern was not associated with the prognostic index or survival.

Superficial spreading melanoma arising in a longstanding melanocytic nevus on the sole

In Asians, the plantar surface is the commonest site for cutaneous melanoma, and most melanomas arising in this region are the acral lentiginous type. Herein we describe a rare case of superficial spreading melanoma arising in a longstanding melanocytic nevus on the sole of a Korean.

Distinctive dermatoscopic features of acral lentiginous melanoma in situ from plantar melanocytic nevi and their histopathologic correlation

BACKGROUND

An acral lentiginous melanoma in situ on the sole is often difficult to differentiate with the naked eye from an acquired plantar melanocytic nevus. Recent technical advances in epiluminescence microscopy have contributed to the differentiation of these two pigmented skin lesions.

OBJECTIVE

In this study, the correlation between dermatoscopic and histopathologic findings of acral lentiginous melanoma in situ on the sole are compared to those of acquired plantar melanocytic nevi.

METHODS

Three acral lentiginous melanomas in situ on the sole, and two cases of acral lentiginous melanoma were compared with 50 acquired plantar melanocytic nevi by means of dermatoscopy and histopathology.

RESULTS

The dermatoscopic surface profiles of acquired melanocytic nevi were composed of linear pigmentation accentuated mainly on the sulcus superficialis. Histologically, some areas of the sulcus superficialis corresponded to rete ridges of the epidermis, and nests of nevus cells were also often located there. In contrast, the acral lentiginous melanomas in situ showed diffuse, irregularly shaped pigmentation distributed in a disorderly fashion over the entire surface. Histologically, isolated areas of proliferation and small nest formations of atypical melanocytes were irregularly distributed in the epidermis.

CONCLUSION

A distinctive dermatoscopic feature of acral lentiginous melanoma in situ is diffuse and irregular pigmentation over the entire surface of the lesion. This feature is helpful for differentiating acral lentiginous melanoma in situ from acquired plantar melanocytic nevi.

Dermatoscopic and videomicroscopic features of melanocytic plantar nevi

Nearly 10% of Japanese people have pigmented nevi on the soles. Since malignant melanoma also occurs on the plantar area in the Japanese, it would be very valuable to be able to differentiate benign and malignant lesions in the early clinical state. We have investigated the epiluminescence microscopic features of 500 melanocytic nevi on the soles of Japanese people using a dermatoscope and a videomicroscope that can magnify lesions from x 10 to x 200. The results showed that the surface profile of benign melanocytic nevi is mainly classified into five types; that 9% of plantar nevi, however, do not fit into this classification and are categorized as a miscellaneous type; and that the other nonmelanocytic disorders, such as verruca vulgaris and black heel, are easily differentiated by their surface profile. More important, the histological examination showed that atypical nevi, malignant melanoma in situ, and acral lentiginous melanoma are exclusively compartmentalized in the miscellaneous type of surface profile. Our data suggested that epiluminescence microscopy may be a useful method for discrimination of plantar benign and malignant melanocytic lesions.

Black heel with atypical melanocytic hyperplasia

Two cases with a black pigmented patch on the heel are reported. Biopsy specimens showed that atypical melanocytic hyperplasia was confined to the epidermis despite the lesion being present for a long time. The diagnosis of atypical melanocytic hyperplasia should be considered in the differential diagnosis of the black heel.

Plantar malignant melanoma in a white Caucasian population

Fifty-one white Caucasian patients from the west of Scotland, with stage I primary malignant melanoma arising on the plantar surface were studied. Subungual lesions were excluded from the study. Clinical and pathological features were related to survival, and compared with a group of 239 cases of clinical stage 1 melanoma of the lower limb, excluding the foot, collected in the same geographical area over the same period of time (1979-84). The average age of patients with plantar melanoma was 67 years and was significantly older than those with leg melanomas, in whom the mean age was 53 years. Twenty patients with plantar lesions had superficial spreading melanomas, 27 had acral lentiginous melanomas, and four had nodular lesions. The female:male ratio was 3:2 which was significantly different from the 7:1 female:male ratio for leg lesions. Plantar melanomas were more commonly ulcerated (57%) than were melanomas on the leg (29%) [P < 0.001]. There was no significant difference between the mean thickness of melanomas on the plantar surface and those on the leg. Nine (17%) of the patients with plantar melanomas gave a clinical history of pre-existing naevus and in 27% there was pathological evidence of a pre-existing naevus. Disease-free survival at 5 years for the population with plantar melanomas was 82, 51 and 0%, respectively, for melanomas 0-1.49, 1.5-3.49 and over 3.5 mm in thickness. This compares with 95, 71 and 46%, respectively, for leg lesions. In each thickness category patients with leg melanomas have a significantly better survival.(ABSTRACT TRUNCATED AT 250 WORDS)