|
Age / Sex : 29 / F
Age/Sex: 29/F
Chief complaint: Left leg pain and palpable mass
1) What is your impression?
Two weeks later, you can see the final diagnosis with a brief discussion of this case.
* Send Application Answers to In Sook Lee, MD (lis@pusan.ac.kr)
Courtesy : Park Ji Seon, Kyung Hee University Medical Center
Diagnosis: Malignant peripheral nerve sheath tumor in neurofibromatosis 1
Discussion
Findings: Irregularly nodular and fusiform shaped mass in popliteal fossa represents intermediate to low signal intensity on T1WI and intermediate signal intensity with central dark signal foci on T2WI, and heterogeneous enhancement. The mass inferiorly extends to thickened tibial nerve and adjacent deep soft tissue edema is seen. And, FS T2W images show several high signal nodules at skin and intramuscular layer, suggesting superficial and intramuscular neurofibromas.
The patient had family history of neurofibromatosis( mother) and physical examination revealed café au lait spots with multiple palpable cutaneous nodules and masses over the entire body.
Differential Diagnosis: Plexiform neurofibroma, soft tissue sarcoma(such as clear cell sarcoma, alveolar soft part sarcoma, epithelioid sarcoma, synovial sarcoma etc..), metastasis.
Diagnosis: Malignant peripheral nerve sheath tumor in neurofibromatosis 1.
Discussion:
* Malignant peripheral nerve sheath tumor(MPNST) accounts for approximately 10% of soft-tissue sarcomas, and 40%–60% of MPNSTs arise from cases of NF1. Overall, there is a 4% chance of malignant transformation in NF1. MPNSTs may arise from plexiform neurofibromas, de novo or secondary to radiation therapy.
* MPNST is generally encountered in young adult and middle-aged patients of both sexes. When associated with neurofibromas, MPSNTs occur more commonly in a younger age group and in men.
* MPNSTs most commonly occur in the deep soft tissues, usually close to a nerve trunk. The most common sites are the sciatic nerve, brachial plexus, and sacral plexus.
* Clinical symptoms are pain, neurologic manifestations, and enlargement of a previously stable neurofibroma.
* Radiologically, MPNSTs and neurofibromas may appear indistinguishable, but, Gallium-67 citrate imaging; MPNSTs have greater uptake compared with benign lesions. Useful MRI findings, suggestive of MPNST, include increased largest dimension of the mass, peripheral enhanced pattern, perilesional edemalike zone, and intratumoral cystic lesion. Superficial plexiform neurofibromas in patients with NF1 are infiltrating lesions with diffuse morphology, asymmetrical distribution, and nontargetlike signal intensity.
* The reported 5-year survival rate for patients with MPNST without NF1 is as high as 50%. It drops to as low as 10% for MPNST patients with NF1
References:
1. Hrehorovich PA, Franke HR, Maximin S, Caracta P. Malignant peripheral nerve sheath tumor, RadioGraphics 2003;23:790–794
2. Resnick, bone and joint imaging, chapter 71. Tumors and tumor-like lesions of soft tissues, p1233-1234
3. Wasa J, Nishida Y, Tsukushi S, Shido Y, Sugiura H, Nakashima H, Ishiguro N. MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas. AJR 2010;194:1568–1574
4. Lim R, Jaramillo D, Poussaint TY, Chang Y, Korf B. Superficial neurofibroma: a lesion with unique MRI characteristics in patients with neurofibromatosis type 1. AJR 2005;184:962-968
|
