# Cutaneous Granular Cell Tumor with Overlying Hypertrichosis in an Adult: A Rare Case Report

## TL;DR

A rare case of a skin tumor with unusual hair growth in an adult is reported, highlighting the importance of combining clinical and pathological findings for accurate diagnosis.

## Contribution

This is the first reported case of a cutaneous granular cell tumor with hypertrichosis in an adult.

## Key findings

- The tumor exhibited prominent terminal hair growth, a rare feature in cutaneous granular cell tumors.
- Histopathology and immunohistochemistry confirmed the diagnosis of a benign granular cell tumor.
- This case expands the known clinical spectrum of cutaneous granular cell tumors.

## Abstract

Granular cell tumors are rare neoplasms of neural origin that may involve the skin and often present with nonspecific clinical features. Accurate diagnosis typically relies on histopathologic examination. Overlying localized hypertrichosis is an uncommon finding in cutaneous granular cell tumors and may further complicate clinical assessment. In this report, we describe a primary cutaneous granular cell tumor with prominent overlying terminal hair growth in an adult patient. This presentation has been reported only once previously in the literature in a pediatric case. Recognition of this rare clinical feature is important, as skin lesions associated with localized hypertrichosis are frequently attributed to other benign or malignant conditions. This case expands the known clinical spectrum of cutaneous granular cell tumors and emphasizes the importance of clinicopathologic correlation in achieving an accurate diagnosis.

Granular cell tumors are uncommon neoplasms of neural origin that may involve the skin and often present with nonspecific clinical features, making diagnosis challenging. Cutaneous granular cell tumors rarely exhibit overlying hypertrichosis, a finding that may obscure their clinical recognition. In this report, we describe a rare case of a primary cutaneous granular cell tumor with prominent overlying terminal hair growth in an adult patient. A 27-year-old woman presented with a slowly enlarging, firm, pigmented plaque on the upper back associated with pruritus and increased hair growth. Histopathologic examination revealed sheets of large polygonal cells with abundant granular eosinophilic cytoplasm, and immunohistochemical staining was positive for S100, SOX10, CD68, and calretinin, confirming the diagnosis. The lesion was completely excised with no evidence of malignancy. To our knowledge, this represents the second reported instance of a cutaneous granular cell tumor associated with hypertrichosis and the first described in an adult. It underscores the importance of clinicopathologic correlation in evaluating unusual cutaneous lesions and expands the spectrum of recognized presentations of cutaneous granular cell tumors.