Primary cutaneous ganglioneuroma: anatomico‐clinical study of 4 cases with focus on Merkel cells.

Cutaneous ganglioneuromas (CGNs) are exceptional. We aim to describe the anatomico‐clinical profile of primary CGN and report 4 cases. Patients were 2 men and 2 women aged 53 to 76 years, who had flesh‐colored nodules on the back, associated with adjacent keratotic changes, that is, epidermal nevus (1 case) or seborrheic keratosis (3 cases). Histopathology showed ganglion cells within a proliferation of Schwann cells. The epidermis was acanthotic, associated with sebaceous induction in 2 cases, with follicular hyperplasia as in fibroepithelial tumors (1 case) or with tricholemmoma (2 cases). Cytokeratin‐20 immunostaining showed Merkel cells in the epidermis. A higher density of Merkel cells was observed in BerEP4+ follicular structures. Along with 16 published cases, our study indicates that a nodule associated with seborrheic keratosis on the back may represent a CGN, a complex mesenchymal and epidermal/follicular lesion of neuroectodermal lineage, associating neuronal proliferation and Merkel cell hyperplasia with follicular induction. [ABSTRACT FROM AUTHOR]