# Chondrosarcoma arising from long-standing Dysplasia Epiphysealis Hemimelica of the proximal humerus: A case report

## TL;DR

A rare case of chondrosarcoma developing from a long-standing skeletal disorder in the shoulder is reported, emphasizing the need for long-term monitoring.

## Contribution

This is the first documented case of chondrosarcoma arising from Dysplasia Epiphysealis Hemimelica.

## Key findings

- Chondrosarcoma was diagnosed nearly 30 years after the initial DEH diagnosis in the proximal humerus.
- The patient was treated with wide resection and shoulder reconstruction using a reverse-constrained arthroplasty.

## Abstract

Dysplasia Epiphysealis Hemimelica (DEH), or Trevor’s disease, is a rare, nonhereditary skeletal disorder involving abnormal cartilaginous overgrowth of the epiphysis. To our knowledge, malignant transformation has not been previously documented. We report a unique case of chondrosarcoma arising from a DEH lesion in the proximal humerus nearly 30 years after the initial diagnosis. The patient was treated with wide resection and reconstruction using a proximal humeral replacement with a reverse-constrained total shoulder arthroplasty. This case highlights the need for long-term follow-up in patients with DEH, especially when new symptoms suggest possible malignant transformation.