# Granular cell tumor of the brachial nerve in a dog: A case report

## TL;DR

This case report describes a rare granular cell tumor in a dog's brachial nerve, highlighting the challenges in diagnosis and surgical removal.

## Contribution

The first documented case of a granular cell tumor originating from the brachial nerve in a dog.

## Key findings

- The tumor was attached to the brachial nerve and required partial nerve removal during surgery.
- Postoperative paralysis occurred in the left thoracic limb following the procedure.
- Histopathology confirmed the diagnosis of granular cell tumor, which is rare in non-oral locations.

## Abstract

Here, we describe the first case of a granular cell tumor (GCT) derived from the brachial nerve. Eleven-year-old neutered female Chihuahua presented to the hospital with a bulge from the left neck to the axilla. The dog had a spherical subcutaneous mass on the cervical subcutis, and cytology hinted at adenocarcinoma or neuroendocrine tumor. However, the origin of the tumor remains unknown. During resection of the mass, bleeding was difficult to control owing to the high blood flow, and tumor removal was extremely difficult. The caudal aspect of the mass was attached to the brachial nerve and had to be removed, along with parts of the nerve fibers. The patient's postoperative course was fair, but it developed paralysis of the left thoracic limb. Pathology revealed that the mass was positive for S100 and vimentin, and GCT was diagnosed. Non-oral GCTs are extremely rare. The clinical diagnosis of GCT is difficult and is often confirmed histopathologically by excision. Although most cases of GCT are benign, they must be recognized as hemorrhagic, indistinct masses that mimic malignancy. Excision carries the risk of hemorrhage and damage to the surrounding tissues to secure margins.