Giant Congenital Melanocytic Nevus (Bathing Trunk Nevus)- A Case Study

Abstract

A thirteen-years-old female child presented to our Dermatology Department, had a large circumferentially pigmented area in front of neck, spread to chest, abdomen to thighs and up to knees as well as same spread to back of body bilaterally, interposed darkened lesions were present. Born by normal delivery to non-consanguineous parents presented with an asymptomatic hyperpigmented encompassing the entire trunk involving chest, back, buttocks and genitalia covering more than 40% of body area present since birth. It has been growing in size with age. The lesions were flat initially and gradually started becoming thicker. Scalp, mucosa, palms, soles and nails were normal. There were no signs of jaundice, haemolysis, meningomyelocele or abnormal hair growth. The rest of the physical examination including cardiovascular, pulmonary and abdominal system and genitourinary functioning was normal. Complete blood picture was within normal range. There was immediate concern of melanoma by Paediatric Dermatology and General Surgery physicians. Magnetic resonance imaging of the lumbar spine and brain revealed no intracranial abnormalities, hydrocephalus or suggestion of meningeal inflammation. Giant congenital melanocytic nevi are rare and occur in about one out of every 2,00,000 to 5,00,000 births. There is a significant association between bathing trunk nevus and neurofibromatosis and lipomatosis. Apart from this association of bathing trunk nevus with abnormalities like spina bifida occulta, meningocoele, club foot and hypertrophy or atrophy of deeper structures of a limb have been described. Biopsy report showed skin with groups of nevoid cells extending into underlying fat, intimately associated with the lobules and surrounding many blood vessels. Pathologic examination revealed benign congenital intradermal nevus without evidence of malignancy. The systemic examination was normal. This is a typical case of giant congenital melanocytic nevus. As the surface area is greater than 50 cm in diameter, the risk of developing melanoma is higher. [1] Congenital melanocytic nevus is a benign neoplasm composed of naevomelanocytes, which occurs in about 1% to 2% of new-borns. Giant congenital melanocytic nevus is a variant of congenital melanocytic nevus, characterised by its extensive size and is defined as melanocytic nevus measuring