Paediatric cellular blue naevus presenting with lymph node involvement: a case report

Cellular blue naevi are benign melanocytic neoplasms typically arising in the dermis. While cases of lymph node involvement have been documented, this is a rare finding and may mimic more clinically concerning lesions including metastatic melanoma. We present the case of a 11-year-old female presenting with a slow growing left neck mass. Excisional biopsy of the mass revealed a cellular pigmented lesion consisting of sheets of spindled cells with occasional whorling formations, nested epithelial areas and a lymphoid cuff. There was no significant pleomorphism. The lesion was positive for SOX10, MelanA, HMB45 and negative for BRAF and PRAME. Molecular studies were undertaken and a gain of chromosome 6p identified. The patient was known to have a congenital pigmented lesion on the scalp, which was subsequently biopsied and showed a similar appearance. These findings supported the diagnosis of a cellular blue naevus of the scalp with involvement of a cervical lymph node.