Intramuscular Myxoma in the Supinator Muscle with Transient Postoperative Posterior Interosseous Nerve Palsy: A Case Report

Right adductor compartment intramuscular myxoma: A rare case report

INTRODUCTION

Extracardiac intramuscular myxomas are exceedingly rare benign tumors, necessitating well-planned management for optimal outcomes.

CASE PRESENTATION

We report the case of a 63-year-old male with no prior medical history, presenting with a progressively enlarging mass within the adductor compartment of the right thigh. Physical examination revealed a mobile and painless mass measuring 70 mm by 50 mm at the level of the adductor compartment of the right thigh, devoid of signs of inflammation or skin lesions. The patient showed no cachexia, asthenia, or weight loss. Imaging exams confirmed the characteristic features of intramuscular myxoma, leading to the decision for complete surgical excision. Subsequent histological analysis confirmed the diagnosis, and the patient experienced no postoperative complications, showing positive long-term follow-up results.

CLINICAL DISCUSSION

In the presence of an intramuscular mass, thorough questioning and meticulous clinical examination enable us to propose a diagnosis of intramuscular myxoma. MRI is the preferred imaging modality, supporting diagnostic reasoning. However, histopathological analysis remains essential to confirm the mass's nature and rule out potential malignant differential diagnoses. Complete surgical resection is considered the gold standard, ensuring favorable results with a low risk of recurrence.

CONCLUSION

Extracardiac intramuscular myxomas are exceptionally rare; MRI and histopathological analysis combined help rule out potential malignant differential diagnoses. Total surgical excision yielded good results with a low risk of recurrence.

OUP accepted manuscript

Intramuscular myxoma (IM) is a rare benign tumour. It may occur at any age but most commonly occurs among older women. The preoperative diagnosis of IM is complicated. The diagnosis can only be definitively established by histopathological examination. The treatment of choice is radical surgical excision. We report a case of a 41-year-old woman with an IM of the biceps brachii muscle.

A Rare Case of Supinator Intramuscular Myxoma with Encasement of the Posterior Interosseous Nerve

Intramuscular myxomas are rare, benign mesenchymal tumors. Tumor location in the forearm is very rare among all the intramuscular myxomas. To the best of our knowledge, there were two cases of supinator intramuscular myxoma reported in the literature, and we intend to report the third case of supinator myxoma with encasement of the posterior interosseous nerve (PIN). A 67-year-old lady presented with history of left proximal forearm swelling for the past 5 years. Magnetic resonance imaging showed a lobulated multiseptated lesion seen within left supinator muscle, which was hyperintense on T2-weighted images (T2WI) and hypointense on T1-weighted images (T1WI), with peripheral enhancement post contrast. The tissue diagnosis of myxoma was confirmed via an open biopsy. She underwent en bloc resection of the tumor. The PIN was encased by the tumor; it was preserved and carefully released from the tumor. The nerve sheath served as an excision margin. In conclusion, we present a rare case of an intramuscular myxoma in the supinator muscle. In view of the location, extra attention should be paid during excision surgery to locate the PIN and to avoid damaging the surrounding structures.