Acral myxoinflammatory fibroblastic sarcoma

Acral myxoinflammatory fibroblastic sarcoma is a rare low-grade sarcoma. It is most commonly found in the extremities but has been reported elsewhere in the body.

Clinical

These lesions present as slow growing painless masses usually in the ankle, foot, wrist or hand. There is normally no overlying skin change.

Plain film X ray may show nothing or slight bone erosion. On MRI these lesions vary considerably. They tend to show the presence of fat and enhance strongly with contrast.

Diagnosis

This is made by biopsy and histological examination.

Histologically these lesions are characterised by (1) an inflammatory background (2) a prominent myxoid component (3) enlarged atypical cells with prominent nucleoli and (4) often a bizarrely shaped nucleus. The cells stain positively for vimentin.

Differential diagnosis

This includes tenosynovitis, pigmented villonodular synovitis, giant cell tumor of the tendon sheath, ganglion cysts and other sarcomas.

Treatment

Complete excision of the lesion is the recommended treatment. Radiation may be useful for local recurrences. It is not known how useful chemotherapy is for this condition as there have been so few cases reported.

Prognosis

This lesion appears to be curable by surgery provided adequate margins are obtained. Local recurrences have been reported in ~40% of cases. Only three cases have reported metastatic disease.

Epidemiology

This is a rare lesion with less than 150 cases described. The male: female ratio is approximately 1. The age range varies between 4 and 87 years with the majority occurring between 35-45 years. The majority of lesions occur in the ankle, wrist foot and hand.

History

This lesion was first described in 1998 independently in three publications.