# Coexistence of Endodermal Cyst and Neurofibromatosis Type 1: A Case Report

## TL;DR

A rare case of a brain endodermal cyst in a patient with neurofibromatosis type 1 highlights the need for broader differential diagnosis in posterior fossa tumors.

## Contribution

This report documents an exceptionally rare co-occurrence of endodermal cyst and neurofibromatosis type 1.

## Key findings

- A 29-year-old male with NF1 was found to have an endodermal cyst in the posterior fossa.
- The cyst was confirmed pathologically with ciliated epithelium but no skin appendages.
- The case suggests a possible, though unproven, association between NF1 and endodermal cysts.

## Abstract

Endodermal cysts (ECs) are rare benign cystic lesions of the central nervous system. Neurofibromatosis type 1 (NF1) is a genetic disorder associated with neural tumors, but co-occurrence with EC is exceedingly uncommon. We report the case of a 29-year-old male with NF1, characterized by café-au-lait spots and a family history, who presented with headache and left upper limb deficits following minor head trauma. Imaging revealed a posterior fossa tumor. Due to progressive neurological decline, the mass was surgically resected. Intraoperative findings showed a yellowish-white, jelly-like accumulation. Pathological examination confirmed the diagnosis of EC, which was characterized by a wall lined with ciliated epithelium, but lacking skin appendages in the cyst wall. This case suggests that ECs should be included in the differential diagnosis of extra-axial tumors in the posterior fossa. Given the rarity of ECs, a potential association with NF1 is suspected in this case, although the causal relationship remains unclear.