Case Report Peripheral Nerve Sheath Tumors. Benign or Malignant? The Role of MRI and Ultrasonography in A Case Report Alexandros Chatzistefanou, MD, Michalis Mantatzis, MD, PhD, Savas Deftereos, MD, PhD, Paraskevi Mintzopoulou, MD, Panos Prassopoulos, MD, PhD From the Department of Radiology, Democritus University of Thrace, University Hospital of Alexandroupolis, Alexandroupolis, Greece Keywords: Peripheral Nerve Tumors, MRI, Ultrasonography, Power Doppler. Acceptance: Received February 12, 2012, and in revised form April 3, 2012. Accepted for publication May 6, 2012. Correspondence: Address correspon- dence to Michalis Mantatzis, MD, PhD, Department of Radiology, Democritus University of Thrace, University Hos- pital of Alexandroupolis, Opsikiou 1, 681 00, Alexandroupolis, Greece. E-mail: mmantatz@med.duth.gr. J Neuroimaging 2012;XX:1-3. DOI: 10.1111/j.1552-6569.2012.00731.x ABSTRACT A 31-year-old male patient admitted to another hospital for investigation of a localized painful hump in the medial surface of his left leg. The clinical examination revealed a painful palpable lump in the medial surface of left thigh that was initially thought to be a hematoma due to a history of recent trauma. However, an ultrasound was requested to exclude deep venous thrombosis (DVT). The US examination revealed a heterogeneous, fusiform lesion with elongated proximal and distal projections in close proximity to su- perficial femoral artery and vein and could not definitely exclude the DVT hypothesis. In a second ultrasound examination performed in our department, a neurogenic origin of the lesion was proposed. A consequent MRI examination confirmed the presence of a fusiform tumor in the anatomic path of the saphenous nerve. This was further confirmed intraop- eratively, and pathologically was diagnosed as a malignant peripheral nerve sheath tumor (MPNST). In this present study the role of ultrasonography, the correlation between MRI and ultrasonographic findings are discussed and a review of the literature is presented. Introduction Soft-tissue tumors are not uncommon, most of them being be- nign. 1 Considering this observation, confronting a mass-like lesion at the extremities with no clear relation to bones, a soft tissue neoplasia should be ruled out. Malignant periph- eral nerve sheath tumors (MPNSTs) include all malignant tu- mors with neural differentiation arising from peripheral nerves and account for 5–10% of all malignant soft tissue tumors with approximately two-thirds of them accompanied by neurofi- bromatosis I (NF-1) (von Recklinghausen’s disease). 2 Sporadic MPNST may occur as secondary neoplasms after radiation ther- apy with a latency of up to two decades. Several imaging modal- ities have been described in the assessment of soft-tissue tumors, including plain radiography, ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), angiog- raphy, and positron emission tomography (PET). 3 However, none of these approaches are reliable for distinguishing benign from malignant lesions with reported criteria suggestive of ma- lignancy, varying widely. Case Presentation We present a case of an otherwise healthy 31-year-old patient, who complained of a painful, localized swelling on the median surface of his left mid-thigh. The initial work-up was performed in another hospital. The clinical examination revealed a painful palpable lump in the medial surface of left thigh. Due to a his- tory of recent trauma and rather unspecific clinical signs, it was initially attributed to a hematoma. An ultrasound that was per- formed to exclude deep venous thrombosis (DVT) revealed a spindle shaped soft tissue mass of mixed echotexture and poste- rior acoustic enhancement. The lesion had elongated proximal and distal projections in close proximity to superficial femoral artery (SFA) and Femoral Vein (FV; former Superficial Femoral Vein; SFV). Although there were no signs of thrombosis in FV, the possibility of a doubled FV with a thrombosed branch was questioned. The patient was referred to our department for fur- ther investigation. A repetitive ultrasound clarified that despite the proximity of the central portion of the lesion with the SFA and FV (Fig 1), the peripheral elongated part was gradually diverged from the vascular bundle ensuing a more superficial and anterior route along the expected route of saphenous nerve, thus suggesting a possible diagnosis of neurogenic tumor. More- over, the middle part of the lesion was bulged, having a rather mass-like appearance, further moving out from the initial as- sumption of a lesion having vascular origin. The borders of the lesion were clearly separated from sartorius muscle, which however was greatly dislocated. A color Doppler examination revealed intrinsic anarchic vascular pattern and a spectral wave- form consistent with neo-angiogenesis. To further characterize the lesion, an magnetic resonance imaging (MRI) examination of the left thigh was performed. A Copyright ◦ C 2012 by the American Society of Neuroimaging 1