Neurocristic Hamartoma With Lymph Node Involvement: A Diagnostic Dilemma.

Neurocristic hamartoma (NH) is a rare dermal melanocytic lesion that is formed due to the aberrant development of neural crest-derived melanocytes during their course of migration through the dermis at the time of embryogenesis. Here, we describe a case of NH in a 6-year-old boy who clinically presented with diffuse plaque-type blue nevus on his scalp with a contiguous extension into the cervical region and lymph node involvement. A subcutaneous nodule displaying a marked histological heterogeneity with lymph node involvement is a very unusual and diagnostically challenging presentation of NH. The importance of an accurate diagnosis of NH lies in the fact that malignant transformation can rarely occur within these lesions over an unpredictable time course and remain undetected, rendering clinical management difficult. Although our child had a benign course after a follow-up of 5 years despite lymph node involvement, the possible risk of development of malignant melanoma in such a lesion warrants long-term surveillance. This case report highlights the unusual clinical presentation and histopathological features of this rare entity along with a relevant review of the literature. The present case also underscores the concept that sentinel lymph node involvement in certain melanocytic lesions in children must not be mistaken for malignant melanoma.