|Year : 2014 | Volume
| Issue : 4 | Page : 230-232
Extra-osseous Ewing's sarcoma of sciatic nerve masquerading as an infected hemangioma: A rare case report
Anjan K Dhua1, Ravindhra Bharathi1, Chokka Mahesh Kiran2, Pappu Paramartha Lingam3, Manoj Joshi1
1 Department of Pediatric Surgery, Pondicherry Institute of Medical Sciences, Kalapet, Puducherry, India
2 Department of Pathology, Pondicherry Institute of Medical Sciences, Kalapet, Puducherry, India
3 Department of Plastic Surgery, Pondicherry Institute of Medical Sciences, Kalapet, Puducherry, India
|Date of Web Publication||30-Sep-2014|
Department of Pediatric Surgery, Pondicherry Institute of Medical Sciences, Kalapet, Puducherry - 605 014
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Extra-osseous Ewing's Sarcoma (EES) arising from the peripheral nerve is rarely reported in children. Here, we report an instance of EES arising from the left sciatic nerve mimicking an infected hemangioma. This case highlights the need for a high index of suspicion and early histological diagnosis to avoid diagnostic delay.
Keywords: Extra-osseous Ewing′s Sarcoma, infected hemangioma, intra-neural Ewing′s Sarcoma, nerve grafting
|How to cite this article:|
Dhua AK, Bharathi R, Kiran CM, Lingam PP, Joshi M. Extra-osseous Ewing's sarcoma of sciatic nerve masquerading as an infected hemangioma: A rare case report. J Indian Assoc Pediatr Surg 2014;19:230-2
|How to cite this URL:|
Dhua AK, Bharathi R, Kiran CM, Lingam PP, Joshi M. Extra-osseous Ewing's sarcoma of sciatic nerve masquerading as an infected hemangioma: A rare case report. J Indian Assoc Pediatr Surg [serial online] 2014 [cited 2018 Oct 19];19:230-2. Available from: http://www.jiaps.com/text.asp?2014/19/4/230/142016
| Introduction|| |
EES is sparingly reported in patients below 10 years of age and the reported incidence is 0.5%.  The reported incidence of EES in lower extremities is 26%.  EES with an intra-neural origin in the lower extremity is very rare. The exact incidence of this entity is not known in children. Only isolated case reports exist in literature.  Because of its rare occurrence and nonspecific presentation, it can pose diagnostic and therapeutic challenges. It may also mimic certain inflammatory masses arising deep to the muscles. Complete surgical excision is the mainstay in treatment, followed by chemotherapy and radiotherapy to prevent recurrence.
| Case report|| |
A six-year-old boy was referred with a painful swelling in the left thigh and difficulty in walking since four months. On examination, a firm swelling approximately five centimeter in size was noted on the posterior mid thigh. The swelling was diffuse, tender, and deep to the muscles. The overlying skin was normal. The child was febrile and total counts were elevated. Sonography reported the possibility of abscess deep to the thigh muscle. He symptomatically responded to antibiotics, analgesics, and rest. Magnetic resonance imaging (MRI) and computer tomography (CT) angiography reported the possibility of an infected hematoma or hemorrhage in non-involuting hemangioma with close proximity to the sciatic nerve [Figure 1]a and b. The child was advised surgical excision for diagnostic confirmation with an explained risk of nerve damage. However, the parents did not give consent, so it was deferred.
|Figure 1: MRI (A) and Contrast enhanced Computerized Tomography (CT) CECT (B) shows a well-defined oval lesion in close proximity to the sciatic nerve with a feeder vessel (arrow) from profunda femoris vessel and enhancement of the lesion with contrast|
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On follow-up, the child developed weakness in the limb. The swelling was now more localized, firm, and non-tender. Fine needle aspiration was done, which revealed small round cells with mitotic figures. He was advised surgical excision. Operative findings revealed a variegated consistency mass in the substance of sciatic nerve [Figure 2]a. The mass originated from the sciatic nerve with no gross involvement of the surrounding tissue [Figure 2]a. The parents were counseled and informed consent was taken for nerve excision. The tumor was excised completely with one centimeter of the intact nerve at the upper and lower pole. In view of an established peroneal neuropathy for distal limb, a size-matching, peroneal nerve was harvested as a donor nerve for autologous nerve grafting. A 7.5-cm-long segment of the peroneal nerve was grafted with 7-0 polypropylene epineural sutures, avoiding any twist or torsion or tension at the anastomotic sites [Figure 2]b.
|Figure 2: (a) Shows the mass arising from the sciatic nerve with the solid arrow marking the proximal and the hollow arrow showing the distal sciatic nerve. (b) Shows the mass has been resected and an interposition nerve graft has bridged the gap|
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Histopathology and immunohistochemistry studies were suggestive of Ewing's Sarcoma in the substance of the sciatic nerve. Nerve endings were tumor free [Figure 3]. Workup for metastasis to lungs and bone marrow was negative. The child is presently on chemotherapy, and a six-month follow-up has not shown any local or distant recurrences. Physiotherapy and transcutaneous electrical stimulation of muscles is being done periodically to avoid muscle atrophy.
|Figure 3: Uniform round cells, having a vesicular to dark chromatin with prominent nucleoli surrounded by a vacuolated to clear cytoplasm. Homer-Wright (arrow) and perivascular (arrowhead) pseudo rosette formation is also seen (H and E stain; 400×)|
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| Discussion|| |
Ewing's Sarcoma of Bone (ESB), Primitive Neuroectodermal Tumor (PNET), EES, and intra-neural Ewing's Sarcoma are grouped into the Ewing's Sarcoma Family of Tumors (ESFT).  Intra-neural Ewing's Sarcoma was first described in 1918 by Stout in a tumor of the ulnar nerve.  A majority of intra-neural EES are described in adults, with the cranio-spinal vault and cauda equina being the common sites.  Intra-neural EES arising from the peripheral nerves located outside the cranio-spinal vault are extremely rare. Extensive search of the English literature revealed only isolated case reports in the adult age group. ,,, The handful of reports also give credence to the fact that intra-neural EES outside the cranio-spinal vault is very rarely reported.
Due to its rare occurrence and low suspicion index, this tumor can pose a diagnostic and therapeutic challenge. The diagnosis may also be delayed as the symptoms and signs are nonspecific. It may clinically mimic as infected hemangioma, hematoma, or abscess. Imaging studies such as ultrasonography, CT angiography, and MRI may also be misleading. Early histological diagnosis is imperative. Esser et al. reported two cases of Ewing's Sarcoma. One case had an intractable left leg pain because of the entrapment of the sciatic nerve with Ewing's Sarcoma and was evaluated with MRI. The images were not conclusive and required CT-guided biopsy for establishing the diagnosis.  This fact is further endorsed by our case where the contrast CT scan suggested the possibility of a lesion to be an infected hemangioma, which discouraged us from performing fine needle aspiration cytology (FNAC) at that time.
Management is best done by a multimodality approach. Surgical excision with clear margins is the mainstay for local clearance. EES is a highly chemosensitive and radiosensitive tumor. Adjuvant chemotherapy and radiotherapy are used for preventing recurrences.  Aggressive surgical approach had been advocated by most of the earlier cases reported in adults. , Similarly, in our case, complete excision was done by sacrificing the involved nerve segment. The gap was bridged by grafting a segment of peroneal nerve. We initially planned for the sural nerve cable graft, but considering the size discrepancy, a segment of peroneal nerve was interposed.
Functional recovery after nerve grafting depends on motor axons reinnervating target muscles across the graft scaffold before neuromuscular junction degeneration occurs. We expect a period of more than one year for re-evaluating the success of the procedure. The reason for this wide timeframe is that the rate of peripheral nerve regeneration is, on average, 0.2-3 mm per day, and the graft in our case was approximately 7.5-cm long.  Subsequently, it has to traverse the distal host nerve lying in situ as well. Until then, electro-stimulation would ensure the receptors at the neuromuscular junction do not degenerate. The various important factors that decide the success of a graft are length of nerve graft required, quality and type of repair, tension on anastomotic site, age of the patient, and many more.  Therefore, a technique involving the use of fine monofilament sutures and taking bites only from the epineurium is advised. Gentle handling of the nerve ends is also important. Usually, not more than 3-6 sutures along the circumference are required. Since children have greater regenerative potential and the ability to adjust to altered nerve reprogramming than older patients,  we hope for a fairly decent functional outcome in our patient; however, a less than satisfactory functional result would then mandate a tendon transfer at a later stage in the follow-up.
The options of nerve excision and delayed grafting are also reported.  This is to avoid neuroma formation at the anastomotic sites, which may create doubt of recurrence. However, we intended to ensure a timely functional recovery so the defect was primarily interposed with a graft.
We emphasize that EES of the sciatic nerve origin is a rarely reported tumor in children. A deep firm-to-hard swelling of long duration in the posterior aspect of the thigh should be viewed with a high degree of suspicion. Irrespective of radiological findings, early histological diagnosis should be sought to avoid diagnostic delay. This may ultimately affect the outcome. Total surgical excision with tumor-free margins is needed for preventing local relapses.
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[Figure 1], [Figure 2], [Figure 3]