Dendritic Cell Neurofibroma with Pseudorosette: An Uncharted Entity at Unusual Sites: Two Case Reports with Literature Review

Abstract

Dendritic cell neurofibroma with pseudorosette (DCNP) is a novel entity of neurofibroma with sparse literature. Neurofibroma is a benign peripheral nerve sheath tumor having many known histological variants including localized, diffuse, plexiform, solitary, cellular, and atypical forms, all of which lead an indolent course. Like other forms of neurofibroma, DCNP usually is located in the dermis or deeper soft tissue or within the nerve trunk. It reveals a characteristic histomorphology of distinct multiple nodules comprising two types of cells: the outer lymphocyte like dark Type I cells (Schwann cell-like) forming pseudorosettes surrounding the inner scattered lighter and larger Type II cells (ganglion/dendritic cell-like). Although histogenesis of these two type of cells is debatable, immunopositivity for S100 suggests the neuronal origin and the fibrous pseudocapsule covering tumor nodules being immunopositive to epithelial membrane antigen (EMA) suggests perineurium. Here, we report two such cases of DCNP at two different yet unusual sites of cervical and perianal regions. Neither patient nor their family members had any features of neurofibromatosis(NF 1). Both the cases were adults, presented with firm nontender subcutaneous nodules of long duration causing pressure symptoms. Those were resected and evaluated for microscopy. Histomorphology aided by immunohistochemistry positivity for S100 and EMA confirmed DCNP. Follow up study after half an year of surgery was uneventful and Patients were found to be relieved of all symptoms. We present this unusual new variant that poses challenge for it’s close histological mimickers like cellular/epithelioid schwannoma and plexiform neuroma and yet want to emphasize the innocuous behavior of tumor that can be cured by surgical resection.

Keywords

• nerve sheath tumor
• neurofibroma
• plexiform
• pseudorosette