Ang WM, Yates P, Robbins P, et al: Recurrent benign solitary intraosseous schwannoma of the tibia: Orthopedics 31: 176, 2008.
Enzinger FM, Weiss SW: “Malignant Tumors of Peripheral Nerves,” in Soft Tissue Tumors, 2nd Ed, p 781, Mosby, Philadelphia, 1988.
Jacobson JM, Felder JM III, Pedroso F, et al: Plexiform schwannoma of the foot: a review of the literature and case report. J Foot Ankle Surg 50: 68, 2011.
Birch R, Bonney G, Wynn Parry CB : “The Peripheral Nervous System and Neoplastic Disease,” in Surgical Disorders of Peripheral Nerves, p 335, Curchill Livingstone, Edinburgh, 1998.
White NB: Neurilemomas of the extremities. J Bone Joint Surg Am 49: 1605, 1967.
Mendeszoon M, Cunningham N, Crockett RS, et al: Schwannoma: a case report. Foot Ankle Online J 2: 4, 2009.
Pasternack WA, Winter-Reiken DJ: Unusually large cellular schwannoma of the foot. JAPMA 95: 157, 2005.
Kline DG, Hudson A : “Classification of Nerve Sheath Tumours,” in Nerve Injuries: Operative Results for Major Nerve Injuries, Entrapments and Tumours, ed by AR Hudson, p 527, WB Saunders Co, Philadelphia, 1995.
Kwon JH, Yoon JR, Kim TS, et al: Peripheral nerve sheath tumor of the medial plantar nerve without tarsal tunnel syndrome: a case report. J Foot Ankle Surg 48: 477, 2009.
Bamanikar S, Kumar H, Soraisham P, et al: Malignant epitheloid schwannoma: a rare tumor causing a diagnostic dilemma. Int J Pharm Biomed Sci 3: 238, 2012.
Schwannomas are rare, slow-growing, benign tumors consisting of Schwann cells. They may cause pressure along a bony structure, resulting in increased pain and discomfort. Less than 1% of schwannomas become malignant, and localization in the foot is uncommon (2%–3% of reported cases).
We present a case of a schwannoma of a branch of the posterior tibial nerve sheath. The goal is to assist in recognition, diagnosis, and treatment of schwannoma in the foot and ankle. This is a case of a 51-year-old male soccer player with a soft-tissue mass along the medial ankle at the tarsal tunnel area with an insidious onset (2 years). Physical examination revealed a 3.0 × 2.5-cm mass; magnetic resonance imaging confirmed location, size, and depth.
Surgical resection of the soft-tissue mass was performed under general anesthesia. The mass was found to be superior to the flexor retinaculum and attached by a small nerve branch of the posterior tibial nerve that traveled through the flexor retinaculum. A tissue specimen was sent to the pathology laboratory, and a schwannoma was confirmed histologically.
Schwannomas can occur after trauma, especially if the posterior tibial nerve or its branches are affected intrinsically or extrinsically, leading to discomfort, pain, and numbness along the tarsal tunnel. Also, unique to this case, a schwannoma may occur along the small branches of the posterior tibial nerve and present anatomically superior to the flexor retinaculum.