Introduction

Intramuscular myxoma is a rare benign soft tissue tumour of mesenchymal origin surrounded by muscular tissue (1,2). Myxomas are slow-growing tumours. They are most commonly localised in the heart muscle, while other rare cases were detected within the muscle tissue of the extremities. It has been reported less frequently in the hip and around the shoulder, trunk, neck and cruris (3). It is observed more frequently among women in the fourth to sixth decades (4,5). Therefore, we aimed to report this rare case.

Case Report

Informed consent was obtained from the patient for the case presentation below. A 56-year-old female patient was evaluated for pain and swelling in the right cruris. The patient had been suffering from this complaint of swelling for six months, with the addition of pain for the last month. On physical examination, the lesion was found to be firm, mobile and painful. The patient was evaluated by ultrasonography and magnetic resonance imaging. The mass was found as well-circumscribed with homogenous signal intensity, located on the proximal cruris anterior-medial side in the subcutaneous fat tissue and having a size of 24x64 mm The lesion was demonstrated by T1 weighted sequences low signal intensity and T2 fat suppressed sequences high signal intensity in the magnetic resonance imaging. The mass, which was distinct from the surrounding tissues, was excised in the form of an en-block with a narrow margin using a longitudinal incision (Figure 1). Histopathology demonstrated a tumour consisting of spindle- and stellate-shaped cells embedded within loose fibrous and myxoid stroma. It was found to be moderately well-circumscribed. Atypical cytologic features and mitotic figures were not detected. The lesion contained fatty tissue areas separated by fibrous bands in the fibroadipous tissues. This benign lesion was defined as a myxoma. The pain and cosmetic complaints were resolved after the surgery. It is thought that the pain complaint may have resulted from the local pressure effect of the mass. Physical examination did not observe any recurrences of the mass during the 2-year postoperative follow-up.

Discussion

Benign and malignant soft tissue tumour, haematoma and abscess should be considered in the differential diagnosis. The intramuscular myxoma has not been observed in the presence of cellular atypia, increased mitotic activity and rapid growth (6). The separation of the borders from the surrounding muscle tissue in the radiological evaluation helps in the differential diagnosis (7). The relationship between intramuscular myxoma and fibrous dysplasia is known. Mazabraud’s syndrome is a rare syndrome in which benign intramuscular myxoma occurs in association with a monostotic or polyostotic form of fibrous dysplasia on the bone (8,9). It may accompany the McCune Albright syndrome (10). Complete excision with narrow margins is advised. The researcher revealed the occurrence of local recurrence in association with the incompletely excised tumours. Metastases and a locally aggressive behaviour have not been observed. Neoadjuvant and adjuvant treatment were not recommended (11).

Intramuscular myxoma should be considered in the differential diagnosis of soft tissue lesions of the lower extremities.

Ethics

Informed Consent: Informed consent was obtained from the patient for the case presentation below.

Peer-review: Externally peer-reviewed.

Authorship Contributions: Surgical and Medical Practices - E.C.; Concept - A.B., E.C.; Design - A.B.; Data Collection or Processing - A.B., E.C.; Analysis or Interpretation - E.C.; Literature Search - A.B., E.C.; Writing - A.B.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.