Giant congenital melanocytic nevus with neurofibroma‐like changes and spina bifida occulta

Abstract

A 12‐year‐old Iranian girl presented with a bathing trunk congenital melanocytic nevus. Multiple other pigmented lesions were present. The nevi were distributed over the entire body including the oral mucosa. There were also bilateral, soft, pendulous tumors and nodules in the area covered by the giant congenital melanocytic nevus. The tumors had been present since birth and showed continuous growth during childhood. She was otherwise healthy. Her parents were not consanguineous. There was no family history of similar lesions.Physical examination revealed a large dark‐brown circumferential plaque extending evenly from the upper back and abdomen down to the lumbar region, buttocks, and thighs (Fig. 1). It had a smooth surface, with excessive growth of hair. There were soft, redundant, exuberant folds of skin overhanging the back and buttock, localized to the area covered by the bathing trunk nevus. On palpation, they appeared as deep, multilobulated masses mimicking giant neurofibromas. There were also several smaller dark‐ or skin‐colored, soft, dermal nodules in this area. On other parts of the integument, there were numerous pigmented nevi of different sizes and colors, including speckled nevi, café‐au‐lait spots, and some clinically dysplastic nevi. There was hypertrichosis over some of the nevi. Mucosal examination revealed dark‐brown macules on the hard palate and conjunctiva. General physical examination was otherwise normal. There was no axillary freckling. Ophthalmologic examination was negative for Lisch nodules, and the fundal appearance was normal. Neurological examination revealed no abnormalities. Spinal X‐ray showed spina bifida occulta in the fifth lumbar vertebra. Brain and spinal magnetic resonance imaging (MRI) with gadolinium contrast was performed to detect neurocutaneous melanosis, which was negative. Two deep incisional biopsies were performed of the proliferative nodules over the hips, with the clinical impression of giant neurofibroma. Histologic examination revealed superficial nests of melanocytes with focal involvement of the dermo‐epidermal junction, extending into the dermis (Fig. 2). The melanocytes became spindle shaped within the reticular dermis (Fig. 3). Immunohistochemical techniques showed strong positive staining for both S100 protein and MART‐1 in both the superficial and deep portions of the proliferation, consistent with a melanocytic nevus.Bathing trunk melanocytic nevus with large, pendulous skin lesions mimicking neurofibromas over the buttocks and lower back and multiple other melanocytic nevi of variable size distributed all over the bodyimageHistologic examination of a pendulous pigmented mass reveals nests of melanocytes extending from the superficial into the deep dermis (low power, hematoxylin and eosin)imageThere is focal involvement of the dermo‐epidermal junction; melanocytes become spindle shaped within the reticular dermis (medium power, hematoxylin and eosin)imageAs the pathological examination was consistent with proliferative nodules in a giant congenital melanocytic nevus, excision of the tumors was planned to improve the cosmetic appearance of the patient and to decrease the possibility of malignant transformation via debulking of the melanocytic mass.