A Case of Schwannoma of the Common Peroneal Nerve in the Knee

Superficial Peroneal Nerve Schwannoma

Schwannomas are benign tumors of the nerve sheath that arise from the proliferation of active peripheral Schwann cells. Although schwannomas are the most common benign peripheral nerve sheath tumors, superficial peroneal nerve schwannomas are rare in published works of literature. We report a 45-year-old woman with a 4-year history of progressively worsening dull aching pain and paresthesia over the right lateral leg. Physical examination revealed a 4 × 3 cm firm palpable mass and a decreased touch and pain sensation over the lateral aspect of the right calf and dorsum of the foot. She also had an electric shock-like pain on palpation and percussion of the mass. Magnetic resonance imaging demonstrated a well-defined, oval, smooth-walled heterogeneous lesion beneath the peroneus muscle with avid postcontrast enhancement and a split fat sign. Fine needle aspiration cytology also suggested the diagnosis of schwannoma. Based on clinical findings of a mass, decreased sensation, and a positive Tinel sign on the dermatome of superficial peroneal nerve, surgical management was decided. Upon surgical exploration, a firm, glistening mass arising from the superficial peroneal nerve was identified, carefully dissected, and shelled out while maintaining continuity of the nerve. At the 5-month follow-up, the patient reported complete resolution of the pain and paresthesia. Physical examination revealed intact sensation in the lower lateral aspect of the right calf and dorsum of the foot. Therefore, surgical excision should be considered a reasonable option in the management of this rare condition, with most patients achieving good to excellent results.

Schwannomas of the peroneal nerves: Clinical and functional results of surgical treatment

OBJECTIVES

Peroneal nerves Schwannomas are rare benign tumors. Literature is still poor of studies about clinical and functional outcomes after surgical treatment. We evaluated the pre-operative presentation of the disease and assessed clinical and functional outcomes after surgery.

METHODS

We collected all the cases of peroneal nerves' neurinoma treated surgically between June 2016 and June 2020. We analyzed each patients' personal data and carried out accurate clinical examinations before and after surgery. MRI was performed both pre-operatively and post-operatively.

RESULTS

We reported 9 cases of peroneal nerves schwannomas: five arising from the common peroneal nerve and four arising from the deep or superficial branches alone. Their mean size was 22.6 mm. Each patient showed sensation deficits before surgery; pre-operative MRC score was 4.2. Pre-Operative MSTS and LEFS scores were 23.6 and 64.4. Surgery was successful in each case. No local recurrence nor major complication occurred. Tumor size was significantly associated with both diagnostic delay and development of pre-operative deficits. Surgery was proven to be globally successful: post-operative evaluations highlighted a marked reduction of neurological signs and overall functional limitations.

CONCLUSIONS

Surgical treatment at early stages of the disease represents a reliable and relatively safe therapeutic option.

Intramural schwannoma involving a vein

Schwannoma involving the blood vessels is a rare phenomenon. So far, only three cases of intravascular schwannoma have been described (all of which were intraluminal), and the origin of the schwannoma in such cases is not yet completely understood. Here, we describe a very rare intramural venous schwannoma in the subcutaneous right prepatellar area of a 31-year-old man. The schwannoma grew by enlarging and thickening the blood vessel wall, between two preserved layers of the vein. In some areas, there was erosion of the luminal layer, with fibrin apposed to the tumor. The tumor expressed S100 and was negative for CD31, CD34, desmin, and smooth muscle actin. The expression of p16 was preserved. Endothelial markers such as CD31 and Factor VIII showed the endothelial lining (which was D2-40-negative) above the tumor. Although degenerative atypia was present, there were no mitotic figures or necrosis identified.

Schwannoma of the vagina - a common tumor but a rare location: A case report

Schwannomas are nerve sheath tumors arising from Schwann cells. These tumors usually present as benign, relatively slow-growing, solitary, encapsulated, painless masses. Schwannomas rarely occur in the vagina, and have not been fully recognized as gynecological tumors. We herein describe the case of a patient who presented with a schwannoma occurring in the wall of vagina, with non-specific symptoms lasting for ~1 year. The vaginal mass was incidentally detected during a sonographic examination and the patient was referred for surgical resection. The surgery was uncomplicated and the vaginal tumor was diagnosed as benign schwannoma. The immunohistochemical examination revealed positivity for vimentin, S-100 and glial fibrillary acidic protein, whereas discovered on GIST-1, CD117, CD34, desmin, smooth muscle actin and cytokeratin were negative. Tumors occurring in the vagina are common and are of variable histological types, with a wide range of pathological characteristics and complications. Schwannoma should be considered in the differential diagnosis in patients presenting with atypical symptoms from the gynecological tract. Immunohistochemical staining is required for confirmation of the diagnosis of schwannoma, and for distinguishing this entity from other homologous tumors.