Myoepithelioma within the carpal tunnel: a case report and review of the literature

Jonathan Cm Clark,Stephen M Schlicht,Ross Pv Mckellar,Peter Fm Choong,Stuart J Galloway

doi:10.1186/1477-7800-6-15

Abstract

Myoepitheliomas of the extremity are rare and usually benign, while a minority display malignant features. This case demonstrates the diagnosis and management of myoepithelioma within the carpal tunnel. Clinical and radiological tumour features were evaluated. Hematoxylin and eosin stained tumour sections were examined, and immunohistochemistry was performed. Histology revealed a nodular mass of epithelioid cells in clusters within a myxoid/chondroid stroma. No mitoses were noted. Cytokeratins, neuron-specific enolase, synaptophysin, glial fibrillary acidic protein, and S100 were positive on immunohistochemistry. A literature review revealed very few prior reports of myoepithelioma in the wrist, and limited data concerning any relationship between recurrence and quality of surgical margins. In this case, wide local excision would have significantly compromised dominant hand function, and therefore a marginal excision was deemed appropriate in the context of bland histological features. Surgical margins noted in future case reports will aid clinical decision making.

Highlights

Myoepithelioma, known as parachordoma, is a rare soft-tissue tumour more commonly associated with the salivary gland [1]
Myoepithelioma may be found attached to tendon sheaths and shares similar radiological findings to ganglions, pigmented villonodular synovitis, and extraskeletal myxoid chondrosarcoma (ESMC)
On the basis of Hornick and Fletcher's data, we still see this as the best option for histologically bland myoepithelioma within the carpal tunnel. This case demonstrates the challenge of diagnosing myoepithelioma, and differentiating it from other benign and malignant tumours

Summary

Introduction

Myoepithelioma, known as parachordoma, is a rare soft-tissue tumour more commonly associated with the salivary gland [1]. Histological diagnosis of myoepithelioma can be difficult and the histological criteria for malignancy are still being defined. These difficulties of diagnosis and the rarity of the tumour provide a management challenge. This case report and literature review outlines the process of diagnosing myoepithelioma in the carpal tunnel, focusing on differential diagnosis and management principles

Methods

Findings

Discussion

Conclusion