Neurocristic cutaneous hamartoma: Case report of a rare entity

Neurocristic cutaneous hamartoma (NCH) is a rare entity characterized by hamartomatous proliferation of melanocytic, neuroid, and mesenchymal tissues. It results from the aberrant development of the neural crest cells. A 29-year-old female presented with a painless pedunculated swelling over the lower back for 1 year. Grossly, the lesion was skin covered polypoidal tissue. Cut section showed gray-white to gray-yellow areas. Histologically, the lesion was composed of mesenchymal elements and ectodermal elements. Mesenchymal elements were composed of lobules of adipocytes, bundles of smooth muscle tissue, and bone tissue. Ectodermal derivative tissues were composed of nerve bundles and melanocytes. Melanocytes showed a normal maturation pattern. Features were suggestive of a hamartomatous lesion favoring NCH. On immunohistochemistry (IHC), melanocytic cells showed strong positivity for S100. They were also positive for HMB45. Spindle-shaped cells in the connective tissue were positive for CD34. IHC supported the histopathological diagnosis. NCH is a rare entity and poses a diagnostic challenge. IHC may be helpful, but a pathologist has to primarily depend on the histopathological characteristics of the lesion for diagnosing the condition.