# Extraskeletal Chondromatosis in a 30-Year-Old Patient: A Rare Case Report

## TL;DR

This case report describes a rare extraskeletal chondroma in a 30-year-old patient's finger and palm, emphasizing its diagnosis and treatment.

## Contribution

The paper presents a rare case of extraskeletal chondromatosis in a young patient, highlighting diagnostic challenges and management.

## Key findings

- The tumor was located on the palmer aspect of the index finger and palm, an uncommon site for extraskeletal chondroma.
- Immunohistochemistry confirmed the diagnosis with S100 and vimentin positivity and a low Ki67% proliferation index.
- Complete surgical removal with the capsule is crucial to prevent recurrence.

## Abstract

The term chondroma refers to a slow-growing benign tumor. When the tumor arises from the medullary cavity, it is referred to as enchondroma, which is a very common bone tumor. However, if it arises from soft tissues, which is extremely rare, it is referred to as soft tissue chondroma or extraskeletal chondroma. Extraskeletal chondromas are uncommon; benign soft tissue tumors that mostly originate from hyaline cartilage are unrelated to the periosteum, tendon, or bone. The most common sites include fingers and toes. The frequent presentation is a slow-growing, firm, painless, and occasionally tender soft tissue mass. Morphologically, it exhibits lobular structures of hyaline cartilage, and hence it becomes difficult to differentiate it from low-grade chondrosarcoma, so the alarming sign of differentiation becomes a must. Recurrence is possible if it is incompletely removed. Complete removal with the capsule is a must to avoid recurrence. Immunohistochemistry remains the cornerstone for a definite diagnosis when S100 protein and vimentin show positivity for tumor cells and the proliferation index (Ki67%) is low. In this study, we present a very uncommon case of a 30-year-old patient with soft tissue chondromatosis of the palmer aspect of the index finger and palm.