Imaging of the lesions in the lateral muscle compartment of the forearm, alias mobile wad of Henry: Demographics, radiological anatomy and surgical relevance.

Introduction: Mobile wad of Henry (MOH) is a preferred surgical term used to describe the lateral compartment muscles of the forearm consisting of brachioradialis, extensor carpi radialis longus and brevis. The lesions in this compartment are uncommon. In this paper, we describe the largest series of the MOH lesions including their demographics, imaging appearances and importance of surgical anatomy whilst managing MOH lesions via radiological or surgical interventions.

Methods: A retrospective search of oncology database for lesions in MOH at our tertiary orthopaedic oncology institute was performed for the last 12 years (2007-2019) after obtaining institutional review board approval. We further analyse data to obtain further clarity of various neoplasms occurring at this particular anatomical site.

Results: We identified 28 patients with MOH lesions with an age range of 8 to 84 years and a male predominance. Imaging-wise, majority of lesions were benign following characteristics of lipomatous tumours, lipomas being the commonest. Other relatively uncommon benign lesions were nodular fasciitis, myositis ossificans and brachioradialis muscle injury; whereas aggressive MOH soft tissue neoplasms included synovial sarcoma and fibrohistiocytoma.

Conclusion: Although majority of MOH lesions are benign, one needs to be aware of spectrum containing uncommon benign and aggressive MOH lesions. When posed with dilemma, the MOH lesions require multidisciplinary approach with close collaboration of the radiologist, the surgeon and the pathologist to decide further management.