Tendonopathy presenting as a recurrence of leiomyosarcoma

Clinical History

18 months following resection of a leiomyosarcoma from the lower leg a mass appeared which was clinically suspicious of a recurrent tumour.

Imaging Findings

This patient presented with a 3-month history of a rapidly enlarging mass over the anterior aspect of her lower leg. She attributed this to a direct blow to the shin. An MR examination was performed which raised the suspicion of a soft tissue sarcoma. A radical excision was performed following confirmation of the diagnosis by core biopsy. Routine abdominal and thoracic CT scans revealed isolated metastases. A right hemi-hepatectomy and right pulmonary metastectomy were performed followed by chemotherapy.

18 months later the patient noticed a swelling at the site of the previous surgery. It was felt that clinically this represented a recurrance of her tumour. However, an MR scan showed tibialis anterior tendonopathy. This was confirmed on biopsy and the patient could be reassured.

Discussion

Leiomyosarcoma represents around 5% of all soft tissue sarcomas. It is a tumour of smooth muscle cells, most common in the 5th and 6th decades of life. The most common sites for leiomyosarcoma are the gastrointestinal system, uterus and retroperitoneal area. On MR scanning the appearances are of a nonfatty mass, with necrosis and marked heterogeniety if large. On T1 weighted scans the density is similar to skeletal muscle and on T2 spin-echo sequqnces the appearances are similar to fat. Leiomyosarcoma is particularly rare in the foot and ankle. Leiomyosarcoma of the extremities caries a poor prognosis, with a mean survival of approximately 24 months. Surgical excision is the mainstay of treatment, followed by chemotherapy and local radiotherapy.

Tendonopathy affecting the anterior compartment of the lower leg is common. In this case it presented as a recurrent tumour, with MR used to make the diagnosis.It seems likely that the tendonopathy was caused by the treatment of the tumour. This may be secondary to the surgical excision or local radiotherapy.

Differential Diagnosis List

Final Diagnosis

Tibialis anterior tendonopathy

URL:	https://www.eurorad.org/case/1337
DOI:	10.1594/EURORAD/CASE.1337
ISSN:	1563-4086