Superficial femoral vein invasion by a benign neurofibroma in a non-neurofibromatosis patient: case report.

OBJECTIVE AND IMPORTANCE: Neurofibromas are benign neural sheath tumors arising from intraneural supporting cells. Such tumors are characteristic of neurofibromatosis Type I (von Recklinghausen disease) but also occur sporadically. Vascular involvement by neurofibromata is rare, but has been described in the past in the context of neurofibromatosis. There is, to our knowledge, no description of vascular involvement by a neurofibroma in a non-neurofibromatosis patient. CLINICAL PRESENTATION: A 40-year-old woman presented with a 4 year history of a right thigh mass associated with diffuse lower extremity pain. She had no other clinical manifestations of neurofibromatosis and no known family member with neurofibromatosis Type II. Magnetic resonance imaging scans revealed a well-defined solid mass in the anteromedial aspect of the right thigh closely associated with the superficial femoral vein. INTERVENTION: The vessel segment and encapsulated mass were resected "en bloc" after proximal and distal ligation of the vein. The pathological appearance of the mass was consistent with a benign neurofibroma that had infiltrated all layers of the vessel. CONCLUSION: Vessel invasion by a benign sporadic neurofibroma is a rare occurrence with potentially severe implications for the patient. It suggests that surgical removal of asymptomatic benign-appearing lesions of that type should be considered if they are adjacent to important anatomical structures.