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Schwannoma of the superficial peroneal nerve presenting as web space pain
Schwannoma of the Superficial Peroneal Nerve Presenting as Web Space Pain A 55-year-old male presented complaining of pain at his right fourth toe and dorsal fourth web space. Physical examination findings pointed to a lesion affecting the superficial peroneal nerve. A schwannoma of the superficial peroneal nerve was subsequently excised, relieving the patient's symptoms. In the differential diagnosis of non traumatic and/or nonarthritic toe and foot pain, benign tumors, including schwannomas of the tibial and peroneal nerves, should be considered.
Cato T. Laurencin, MO, Ph0 1 ,2 Michael Bain, MMS3
A schwannoma is a benign or rarely malignant tumor arising in peripheral nerves or nerve roots (1-3). The tumors are composed of cells ensheathing these nerves. Schwannomas may occur singly or multiply and have been found in a number of locations. For instance, Inoue et at. have described a case of schwannoma of the brachial plexus (4), whereas Pershing et at. have described a case of sciatic nerve schwannoma presenting as a tarsal tunnel syndrome (5). More distally occurring schwannomas have also been found to produce symptoms of tarsal tunnel syndrome (6, 7). The authors describe a case of a schwannoma of the superficial peroneal nerve presenting with symptoms of toe and web space pain. Case Report
A 55-year-old male presented with a 6-month history of pain of his right fourth toe and fourth web space. The pain was of spontaneous onset and characterized as burning and nonradiating. He experienced these symptoms most often while sleeping or when sitting in a chair with his right leg crossed over his left leg. This pain was also experienced upon standing after a night's rest. The frequency and duration of pain was not increased with walking or changes in footwear. There was no associated 1 Department of Orthopaedic Surgery, The Medical College of Pennsylvania, and Hahnemann University, Philadelphia, PA. Address correspondence to: 3300 Henry Ave., Philadelphia, PA 19129. 2 Department of Chemical Engineering, Drexel University, Philadelphia, PA. 3 The Medical College of Pennsylvania, and Hahnemann University School of Medicine, Philadelphia, PA. 4 Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, OH. 5 Department of Orthopaedic Surgery, Beth Israel Hospital, Boston, MA. 1067-2516/95/3406-0532$3.00/0 Copyright © 1995 by the American College of Foot and Ankle Surgeons
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James J. Vue, M04 Hyman Glick, M05 swelling, skin discoloration, nor paresthesias noted. His significant past history included a blunt trauma injury, when an automobile tire rolled over his right forefoot, without fracture approximately 10 years before presentation. Physical examination revealed a normal-appearing right foot without swelling and with a full range of motion. His foot was not tender to palpation over the web spaces, phalanges, metatarsals, or tarsals. He experienced no pain with passive or active plantar or dorsiflexion of his foot. There was a peculiar sensitivity to light touch over the fourth toe and dorsal fourth web space which appeared to reproduce his pain. Pin prick sensation was normal and did not reproduce his symptoms. No palpable mass or click was appreciated in the area between the third and fourth, or fourth and fifth metatarsals. Motor function of the deep and superficial peroneal nerves was normal. However, with active foot inversion (with and without resistance), he experienced pain and sensory discomfort on the dorsum of his right fourth toe and fourth web space which did not radiate proximally to his calf, thigh, or buttock. Palpation in the region of the superficial peroneal nerve of the right leg at the mid-calf level reproduced the pain and hypersensitivity on the dorsum of the foot at his right fourth toe which he experienced at night. In addition, palpation of the same site on the leg revealed a small area of palpable fullness. A positive Tinel's sign was present in that same area of fullness. Roentgenogram analysis of the patient's right foot and leg was normal. After undergoing a conservative program of salicylate treatment for 6 weeks with no relief, the region of proximal leg radiating tenderness and palpable fullness (approximately 15 em. distal to the fibular head) was explored. At surgery, a mass was found ensheathing the superficial peroneal nerve (Fig. 1). It was excised without damage to the superficial peroneal nerve. By histo-
THE JOURNAL OF FOOT AND ANKLE SURGERY
for an erroneous diagnosis of Morton's neuroma (10). This patient experienced no apparent motor or sensory loss immediately after surgery and his paresthesias and pain were relieved. Treatment by complete excision resulted in long-term relief of symptoms. In summary, schwannomas are benign nerve sheath tumors that can present in various locations. In the differential diagnosis of nontraumatic and/or nonarthritic toe and foot pain, benign tumors, particularly schwannomas of the tibial and peroneal nerves should be considered. Treatment by excision can result in relief of symptoms and maintenance of function. Figure 1. Intraoperative photograph of the superficial peroneal nerve at the lateral leg, with mass arising from it.
logical examination the mass was found to be a benign schwannoma. Six weeks postoperatively, the patient's symptoms had completely abated. Upon re-evaluation 2 years later, the patient remained symptom free. He was able to walk without assistance and without pain. Discussion
Schwannomas, also known as neurilemomas and neurinomas, are usually benign, but occasionally malignant tumors that develop from cells within the nerve sheath. Neurofibromas are closely associated with schwannomas. While these two entities are distinct, they may be difficult to clearly differentiate histologically and clinically (1, 2). Whereas neurofibromas are sometimes encapsulated, and are often subcutaneous or located in the distal portions of nerves, schwannomas are consistently encapsulated and are usually located proximally on nerves or on spinal roots. Clinically, it is important to note that (in contrast to neurofibromas) no nerve fibers are found within schwannomas. Schwannomas have been found to be present in such varied locations as the brachial plexus (4) and the sciatic nerve (1, 5). Rarely, schwannomas can be found in the leg (6-12) or in the foot and ankle region (13, 14). This patient presented with dorsal toe and foot pain. This has been observed by others (8) to occur with schwannomas of the leg. The patient's perceived web space pain could have lead to an incorrect diagnosis of a Morton's neuroma. Indeed, Smith and Amis have described a case of tibial nerve neurilemmoma where excision of the first intermetatarsal nerve was performed
References 1. Dubisson, A., Fissette, J., Vivario, M., Reznick, M., Sevenaert, A. A benign tumor of the sciatic nerve: case report and review of the literature. Acta Neurol. Belg. 91:5-11, 1991. 2. Halliday, A. L., Sobel, R. A., Maruza, R. L. Benign spinal nerve sheath tumors: their occurrence sporadically in neurofibromatosis types 1 and 2. J. Neurosurg. 74:248-253, 1991. 3. Robbins, S. L., Cotran, R. Pathologic Basis of Disease, pp. 14451446, WB Saunders Co., Philadelphia, 1989. 4. Inoue, M., Kawano, T., Matsumura, H., Mori, K., Yoshida, T. Solitary benign schwannoma of the brachial plexus. Surg. Neurol. 20:103-108, 1983. 5. Pershing, J. A., Nachbar, J., Vollmer, D. G. Tarsal tunnel syndrome caused by sciatic nerve schwannoma. Ann. Plast. Surg. 20:252-255, 1988. 6. Janeck, C. J., Dovberb, J. K. Tarsal tunnel syndrome caused by neurilemoma of the medial plantar nerve. J. Bone Joint Surg. 59A:127-128, 1977. 7. Levin, A. S., Titchenal, W.O., Clark, J. Tarsal tunnel syndrome secondary to neurilemoma. A case report. J. A. P. A. 67:429-431, 1977. 8. Levy, M., Seelenfreund, M., Maor, P., Lotem, M. Neurilemoma of the peripheral nerves. A report of fourteen cases, including three of the lateral popliteal nerve. Acta Orthop. Scand. 45:337-345, 1974. 9. Menon, J., Dorfman, H. D., Renbaum, J., Friedler, S. Tarsal tunnel syndrome secondary to neurilemoma of the medial plantar nerve. J. Bone Joint Surg. 62:301-303, 1980. 10. Smith, W., Amis, J. A. Neurilemoma of the tibial nerve. J. Bone Joint Surg. 74A:443-444, 1992. 11. Taguchi, Y., Nosaka, K., Yasuda, K., Teramoto, K., Mano, M., Yamamoto, S. The tarsal tunnel syndrome: report of two cases of unusual cause. Clin. Orthop. 217:247-252, 1987. 12. Tourne, Y., Saragalia, D., Rose-Pittet, L., Bute!, J. A propos diun cas de schwannoma benin du nerf tibial posterieur. Guerison par exerese simple sans greffe nerveuse. J. Chir. (Paris). 126:204-205, 1989. 13. Tedder, J. L., Insler, H. P., Antoine, R. Tarsal tunnel syndrome secondary to neurilemoma. Orthop. Rev. 21:613-617, 1992. 14. Zivot, M. L., Pitzer, S., Pantig, F. L., Nathan, L. E. Malignant schwannoma of the medial plantar branch of the posterior tibial nerve. J. Foot Surg. 29:130-134, 1990.
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Cato T. Laurencin, MO, Ph0 1 ,2 Michael Bain, MMS3
A schwannoma is a benign or rarely malignant tumor arising in peripheral nerves or nerve roots (1-3). The tumors are composed of cells ensheathing these nerves. Schwannomas may occur singly or multiply and have been found in a number of locations. For instance, Inoue et at. have described a case of schwannoma of the brachial plexus (4), whereas Pershing et at. have described a case of sciatic nerve schwannoma presenting as a tarsal tunnel syndrome (5). More distally occurring schwannomas have also been found to produce symptoms of tarsal tunnel syndrome (6, 7). The authors describe a case of a schwannoma of the superficial peroneal nerve presenting with symptoms of toe and web space pain. Case Report
A 55-year-old male presented with a 6-month history of pain of his right fourth toe and fourth web space. The pain was of spontaneous onset and characterized as burning and nonradiating. He experienced these symptoms most often while sleeping or when sitting in a chair with his right leg crossed over his left leg. This pain was also experienced upon standing after a night's rest. The frequency and duration of pain was not increased with walking or changes in footwear. There was no associated 1 Department of Orthopaedic Surgery, The Medical College of Pennsylvania, and Hahnemann University, Philadelphia, PA. Address correspondence to: 3300 Henry Ave., Philadelphia, PA 19129. 2 Department of Chemical Engineering, Drexel University, Philadelphia, PA. 3 The Medical College of Pennsylvania, and Hahnemann University School of Medicine, Philadelphia, PA. 4 Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, OH. 5 Department of Orthopaedic Surgery, Beth Israel Hospital, Boston, MA. 1067-2516/95/3406-0532$3.00/0 Copyright © 1995 by the American College of Foot and Ankle Surgeons
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James J. Vue, M04 Hyman Glick, M05 swelling, skin discoloration, nor paresthesias noted. His significant past history included a blunt trauma injury, when an automobile tire rolled over his right forefoot, without fracture approximately 10 years before presentation. Physical examination revealed a normal-appearing right foot without swelling and with a full range of motion. His foot was not tender to palpation over the web spaces, phalanges, metatarsals, or tarsals. He experienced no pain with passive or active plantar or dorsiflexion of his foot. There was a peculiar sensitivity to light touch over the fourth toe and dorsal fourth web space which appeared to reproduce his pain. Pin prick sensation was normal and did not reproduce his symptoms. No palpable mass or click was appreciated in the area between the third and fourth, or fourth and fifth metatarsals. Motor function of the deep and superficial peroneal nerves was normal. However, with active foot inversion (with and without resistance), he experienced pain and sensory discomfort on the dorsum of his right fourth toe and fourth web space which did not radiate proximally to his calf, thigh, or buttock. Palpation in the region of the superficial peroneal nerve of the right leg at the mid-calf level reproduced the pain and hypersensitivity on the dorsum of the foot at his right fourth toe which he experienced at night. In addition, palpation of the same site on the leg revealed a small area of palpable fullness. A positive Tinel's sign was present in that same area of fullness. Roentgenogram analysis of the patient's right foot and leg was normal. After undergoing a conservative program of salicylate treatment for 6 weeks with no relief, the region of proximal leg radiating tenderness and palpable fullness (approximately 15 em. distal to the fibular head) was explored. At surgery, a mass was found ensheathing the superficial peroneal nerve (Fig. 1). It was excised without damage to the superficial peroneal nerve. By histo-
THE JOURNAL OF FOOT AND ANKLE SURGERY
for an erroneous diagnosis of Morton's neuroma (10). This patient experienced no apparent motor or sensory loss immediately after surgery and his paresthesias and pain were relieved. Treatment by complete excision resulted in long-term relief of symptoms. In summary, schwannomas are benign nerve sheath tumors that can present in various locations. In the differential diagnosis of nontraumatic and/or nonarthritic toe and foot pain, benign tumors, particularly schwannomas of the tibial and peroneal nerves should be considered. Treatment by excision can result in relief of symptoms and maintenance of function. Figure 1. Intraoperative photograph of the superficial peroneal nerve at the lateral leg, with mass arising from it.
logical examination the mass was found to be a benign schwannoma. Six weeks postoperatively, the patient's symptoms had completely abated. Upon re-evaluation 2 years later, the patient remained symptom free. He was able to walk without assistance and without pain. Discussion
Schwannomas, also known as neurilemomas and neurinomas, are usually benign, but occasionally malignant tumors that develop from cells within the nerve sheath. Neurofibromas are closely associated with schwannomas. While these two entities are distinct, they may be difficult to clearly differentiate histologically and clinically (1, 2). Whereas neurofibromas are sometimes encapsulated, and are often subcutaneous or located in the distal portions of nerves, schwannomas are consistently encapsulated and are usually located proximally on nerves or on spinal roots. Clinically, it is important to note that (in contrast to neurofibromas) no nerve fibers are found within schwannomas. Schwannomas have been found to be present in such varied locations as the brachial plexus (4) and the sciatic nerve (1, 5). Rarely, schwannomas can be found in the leg (6-12) or in the foot and ankle region (13, 14). This patient presented with dorsal toe and foot pain. This has been observed by others (8) to occur with schwannomas of the leg. The patient's perceived web space pain could have lead to an incorrect diagnosis of a Morton's neuroma. Indeed, Smith and Amis have described a case of tibial nerve neurilemmoma where excision of the first intermetatarsal nerve was performed
References 1. Dubisson, A., Fissette, J., Vivario, M., Reznick, M., Sevenaert, A. A benign tumor of the sciatic nerve: case report and review of the literature. Acta Neurol. Belg. 91:5-11, 1991. 2. Halliday, A. L., Sobel, R. A., Maruza, R. L. Benign spinal nerve sheath tumors: their occurrence sporadically in neurofibromatosis types 1 and 2. J. Neurosurg. 74:248-253, 1991. 3. Robbins, S. L., Cotran, R. Pathologic Basis of Disease, pp. 14451446, WB Saunders Co., Philadelphia, 1989. 4. Inoue, M., Kawano, T., Matsumura, H., Mori, K., Yoshida, T. Solitary benign schwannoma of the brachial plexus. Surg. Neurol. 20:103-108, 1983. 5. Pershing, J. A., Nachbar, J., Vollmer, D. G. Tarsal tunnel syndrome caused by sciatic nerve schwannoma. Ann. Plast. Surg. 20:252-255, 1988. 6. Janeck, C. J., Dovberb, J. K. Tarsal tunnel syndrome caused by neurilemoma of the medial plantar nerve. J. Bone Joint Surg. 59A:127-128, 1977. 7. Levin, A. S., Titchenal, W.O., Clark, J. Tarsal tunnel syndrome secondary to neurilemoma. A case report. J. A. P. A. 67:429-431, 1977. 8. Levy, M., Seelenfreund, M., Maor, P., Lotem, M. Neurilemoma of the peripheral nerves. A report of fourteen cases, including three of the lateral popliteal nerve. Acta Orthop. Scand. 45:337-345, 1974. 9. Menon, J., Dorfman, H. D., Renbaum, J., Friedler, S. Tarsal tunnel syndrome secondary to neurilemoma of the medial plantar nerve. J. Bone Joint Surg. 62:301-303, 1980. 10. Smith, W., Amis, J. A. Neurilemoma of the tibial nerve. J. Bone Joint Surg. 74A:443-444, 1992. 11. Taguchi, Y., Nosaka, K., Yasuda, K., Teramoto, K., Mano, M., Yamamoto, S. The tarsal tunnel syndrome: report of two cases of unusual cause. Clin. Orthop. 217:247-252, 1987. 12. Tourne, Y., Saragalia, D., Rose-Pittet, L., Bute!, J. A propos diun cas de schwannoma benin du nerf tibial posterieur. Guerison par exerese simple sans greffe nerveuse. J. Chir. (Paris). 126:204-205, 1989. 13. Tedder, J. L., Insler, H. P., Antoine, R. Tarsal tunnel syndrome secondary to neurilemoma. Orthop. Rev. 21:613-617, 1992. 14. Zivot, M. L., Pitzer, S., Pantig, F. L., Nathan, L. E. Malignant schwannoma of the medial plantar branch of the posterior tibial nerve. J. Foot Surg. 29:130-134, 1990.
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