Acral Lentiginous Melanoma treated by wide excision with split-thickness skin graft: Case in images

ABSTRACT

@#Acral lentiginous melanoma (ALM) is the rarest of the four subtypes of cutaneous melanoma.1 It accounts for only 2-8% of melanomas in caucasians.2 Only 52 cases of ALM have been recorded in the Philippine Dermatological Society Health Information System from 2011 to 2016.3 Histopathologic demonstration of cytologic atypia, presence of mitoses in the deep dermis, pagetoid spread of epidermal melanocytes and lack of maturation of nests with descent into the dermis are features diagnostic of melanoma.2 4 ALM is primarily managed through wide surgical excision. The most common sites for ALM are the soles, palms, and subungual areas.2 The rarity of ALM, the inconspicuousness of the locations of some lesions, and the difficulty in discerning ALM from benign lesions and traumatic changes usually delay the diagnosis and contribute to the poor prognosis of the disease.4 5 6 A 53-year-old male consulted us for an enlarging pigmented plaque on the sole of his left foot. The lesion started as a junctional nevus, which the patient had since birth. The nevus, originally measuring approximately 0.5 x 0.5 cm, started to increase in size one year prior to the consultation. One month before consultation, the patient noted a black nodule on the center of the lesion. A week before consultation, the lesion bled and became painful after manipulation by the patient. Dermatologic examination of the plantar aspect of the left foot revealed a 1.7 x 1.6 cm, dark brown-black, asymmetric plaque with cobblestone-like surface and a black indurated nodule on the center (Figure 1A). Dermoscopic findings of bluish white veil and irregular pigmentation with variable hypopigmented blotches are suggestive of acral melanoma (Figure 1B). Skin punch biopsy and immunohistochemical stains for S100, Melan A, HMB-45, and KI-67 confirmed the diagnosis of ALM (Figure 2, 3). We did a wide local excision of the lesion with a 2-cm margin from the tumor edge, with depth up to the suprafascial level (Figure 4A). The excisional defect was repaired with a split-thickness skin graft taken from the patient’s skin on the right thigh (Figure 6), which provided excellent aesthetic result. We also did a sentinel lymph node biopsy on the left inguinal area (Figure 5A,B). Frozen section biopsy showed solid nests of atypical melanocytes invading the surrounding fibrous stroma. Individual cells exhibit round to oval, deeply basophilic nuclei and abundant, clear to eosinophilic cytoplasm. Some areas showed prominent melanin pigmentation. Sections along lines of resection, lymphovascular channels, nerves and adipose tissues of the excised mass (Figure 4 B,C) and lymph nodes from sentinel biopsy were all devoid of malignant tumor cells. Histopathologic findings from frozen section biopsy and permanent section biopsy were both consistent with malignant melanoma with 3 mm Breslow thickness. The patient’s postoperative course, including wound healing, was uneventful (Figure 7). During the patient’s 12-month follow up period, we did not observe any signs of local or distant recurrence of the tumor.