Nevus comedonicus. Clinical case

Nevus comedonicus is a rare benign hamartoma of the sebaceous follicle which is more common on the face, neck, shoulders, chest or abdomen. Nevus is group of small or large open comedones. It is a type of organoid epidermal nevus and usually appears before the age of 10 years. The linear configuration of the lesion along Blaschko’s lines suggests that the nevus is a manifestation of mosaicism. A possible cause of nevus comedonicus is mosaic postzygotic mutation of the NEK9 gene. Nevus comedonicus syndrome is also associated with extracutaneous abnormalities. Extracutaneous manifestations most often include ocular abnormalities: ipsilateral cataracts and corneal changes. Associated skeletal abnormalities include abnormalities of the fingers/toes (polysyndactyly or clinodactyly, etc.), scoliosis and other spinal malformations. We present our patient with a large nevus comedonicus localized on the left half of the abdomen with transition to the thigh. The lesion consists of multiple densely located elements with a diameter up to 1–2 mm in the form of expanded orifices of hair follicles — open comedones and inflammatory nodes. Scars remain in place of resolved nodes. A feature of the nevus in our patient is the large size of the nevus and the presence of inflammatory nodes. Dermoscopy reveals numerous light and dark brown, round or barrel-shaped, homogeneous areas with protruding keratin plugs. The treatment was carried out at the clinic with minocycline and gel adapalene externally. Thus, comedo nevus is a rare skin pathology that usually appears at birth and can affect any area of the skin. It can be an isolated skin pathology or as a component of comedo nevus syndrome, which requires additional examination of patients.