Solitary Fibrous Tumor of the Lower Leg: A Rare and Difficult Diagnosis

Abstract

Solitary fibrous tumor (SFT) is a rare neoplasm that commonly originates in the pleura. Extrapleural locations are rare and for this reason sometimes difficult to diagnose. Malignant forms with local recurrence or distant metastases have been reported, also as a consequence of inappropriate treatment. In this article, we report the case of an SFT of the lower leg in a 37-year-old man. Leg SFT is a rare occurrence, and differential diagnosis may be difficult because they can mimic a variety of benign and malignant mesenchymal tumors; immunohistochemical analysis for CD34, CD99, vimentin, and Bcl-2 is necessary. Misdiagnosis carries a significant risk of inadequate removal with subsequent increased risk of recurrence and distant metastases.

Fig. 1.

This figure compares the resected specimen (A) with the MRI (B) and arteriography (C). The hourglass shape, due to the footprint of the interosseous membrane, is clearly visible in both A and B. The MRI shows a well-defined, homogeneously intense mass, findings suggestive of a tumoral lesion with expansile growth. The arteriography shows a peroneal artery that seems to end in the mass and the branches from the PTV and ATV that nourish the mass.

Fig. 2.

Lateral view after fibula removal. This access provides wide exposure of the interosseous space and full control on the ATV and PTV and peroneal vessels, together with the tibial nerve. The mass is visible on the distal part of the field close to the tip of the retractor that holds the peroneal and anterior tibial muscles and the anterior neurovascular bundle. The planned peroneal vessels resection excluded preservation of the devascularized fibular segment removed for exposure because a 12-cm nonvascularised graft would have carried a high risk of failure and pseudoarthrosis.