International Journal of Clinical & Medical Images

Abstract A 14 year old boy presented with a bathing trunk naevus since birth which progressively showed hypertrichosis, nodularity and areas of lax skin

Clinical presentation A 14 year old boy, product of a non-consanguinous marriage and born by normal vaginal delivery presented with history of a circumscribed light brown patch over the back since birth which progressively became darker and increased in size to involve whole of the back, major portion of the chest and abdomen and proximal parts of upper and lower limbs. There is history of progressively increasing hair growth, thickening and development of nodular lesions over the dark brown patch. The developmental history is normal. General physical and systemic examination is normal. Cutaneous examination reveals light to dark brown area with increased terminal hairs, thickening and erythematous nodules at places covering the whole of the back, major portion of the chest and abdomen and proximal parts of upper and lower limbs. Few areas of lax skin (anetoderma) were also present over the back. The histopathology was consistent with melanocytic naevus with areas of elastolysis.

Discussion Congenital melanocytic naevi are a type of melanocytic naevi which are found in infants at birth. The majority of these naevi are found in the region of head and neck and the estimated prevalence is approximately 1% of the infants worldwide. These are divided into small (<2 cm) medium-sized (2-20 cm) and giant melanocytic naevi also known as bathing trunk naevus or garment naevus (>20 cm). Surgical excision is the standard of care for large naevi. The risk of malignant transformation into melanoma vary from 2-42% in the literature, but are most commonly considered to be at the low end of that spectrum due to early observer bias.