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Schwannoma of the median nerve: Iatrogenic injury after axillary lymph node biopsy
Schwannoma of the median nerve: Iatrogenic injury after axillary lymph node biopsy Arin K. Greene, MD, MMSc, James W. May, Jr, MD, and Jonathan M. Winograd, MD, Boston, Mass
From the Division of Plastic Surgery, Massachusetts General Hospital, and Harvard Medical School
SCHWANNOMA, A BENIGN TUMOR of schwann cells, produces a well-circumscribed, slowly growing lesion.1 Although usually painless, pain or deficit in the nerve distribution can occur. Because of its fixation within the body of the nerve, a schwannoma often is mobile in a transverse, but not longitudinal, axis. Diagnosis is facilitated by magnetic resonance imaging, which shows a homogeneous mass that has well-defined borders and is hypo-isointense in T1-weighted images and hyperintense in T2weighted images, reflecting the high lipid content present in myelin produced by these cells.2 Although schwannoma is the most common benign peripheral nerve lesion, nerve tumors comprise less than 5% of all upper extremity tumors. Schwannoma usually occurs in the forearm and hand, but cervical and axillary schwannomas have been documented.2,3 While nerve injury has been described after cervical node biopsy,4 iatrogenic nerve injury has not been reported after axillary node biopsy. Here we report 2 cases of median nerve transection after presumptive axillary lymph node biopsy for suspected malignancy. In both cases, the axillary mass was not a lymph node, but a median nerve schwannoma. CASE REPORTS Patient 1. A 34-year-old, right hand dominant female presented to a general surgeon with a several-week history of an enlarging, 1.5-cm, firm, mobile mass in her left axilla. The patient had a past medical history significant for asthma and depression. She smoked 1 pack of cigarettes daily, and her mother and 2 aunts had
Accepted for publication October 1, 2004. Reprint requests: Jonathan Winograd, MD, Massachusetts General Hospital, Division of Plastic Surgery, 15 Fruit St, Wang 453, Boston, MA 02114. E-mail: [email protected]. Surgery 2005;137:378-9. 0039-6060/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.surg.2004.10.007
378 SURGERY
died of breast cancer. The mass was diagnosed clinically as an enlarged lymph node. Fine-needle aspiration to rule out malignancy was nondiagnostic, and she underwent excisional biopsy. In the recovery room, the patient complained of numbness in her left hand, which was attributed to the local anesthesia. Five days postoperatively, the patient presented with an abnormal hand examination consisting of the inability to flex the interphalangeal joint of her thumb, oppose her thumb, or flex the proximal interphalangeal and distal interphalangeal joints of her index finger. The pathologic diagnosis of the excised axillary lesion was schwannoma. The patient was eventually referred to our plastic surgery division and was noted to have absent function of her median nerve clinically. At that point, a median nerve injury was suspected, and a nerve conduction study and electromyography were obtained. These tests demonstrated an absence of motor and sensory conduction in the median nerve. Three months after schwannoma excision, exploration of the median nerve was performed. Intraoperative nerve conduction studies across the affected area of the median nerve showed complete absence of conduction. A 5-cm gap of median nerve was replaced with scar (Fig 1, A). The neuroma was excised to healthy fascicles, leaving a total gap of 7 cm (Fig 1, B). Six cable nerve grafts were used to reconstruct the gap by using 33 cm of sural nerve in addition to the median antebrachial cutaneous nerve on the affected side (Fig 1, C). Two months after the median nerve reconstruction, tendon transfers were performed for the patient’s high median nerve palsy. Specifically, the flexor digitorum profundus of the index finger was transferred to the flexor digitorum profundus of the middle, ring, and small fingers. The brachioradialis was transferred to the flexor pollicis longus. Subsequently, the patient underwent opponensplasty with her extensor indicus proprius tendon. At her last follow-up appointment 8 months after her median nerve grafting, she has an advancing Tinel’s sign to the level of the elbow. Patient 2. A 33-year-old female treated for Hodgkin’s lymphoma at age 12 years presented with a several-week history of an enlarging right axillary mass. The mass was thought to be lymphadenopathy secondary to recurrent Hodgkin’s disease, and an excisional biopsy was performed. Postoperatively, the patient developed a com-
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Fig 2. A, Median nerve schwannoma. B, Enucleation of schwannoma and involved fascicle. Fig 1. A, Five-centimeter length of median nerve injury after excision of schwannoma thought to be an enlarged lymph node. B, Seven-centimeter gap after neuroma excision. C, Reconstructed median nerve with sural and median antebrachial cutaneous nerve grafts. plete median nerve palsy and complete sensory deficit. The pathologic diagnosis again was schwannoma. The patient was referred to our plastic surgery division 3 years after her injury. Currently, she is weighing her options regarding the reconstruction. She is admittedly hesitant to undergo any more surgery.
DISCUSSION Lymphadenopathy is the most common cause of an axillary mass. Although most lymphadenopathy is due to a benign cause, biopsy often is indicated to rule out malignancy. In addition to lymphadenopathy, the differential diagnosis of an axillary mass includes lymphatic malformation, lipoma, cysts, hidradentitis suppurativa, or dermatofibroma. Schwanomma should be included in the differential diagnosis of axillary masses because schwannoma also has been reported in the axilla.2,3 In addition, schwanoma often is confused with other soft tissue masses, and inadvertent nerve biopsy may lead to permanent disability. Seventeen percent of peripheral nerve trauma is due to iatrogenic injury.5 Although injury to the spinal accessory nerve has been documented after cervical lymph node biopsy,4 nerve injury after axillary lymph node biopsy has not been reported previously. The 2 patients presented in this report had a high index of suspicion for axillary node lymphadenopathy due to neoplasia based on family and personal medical history. However, nerve tumors should be included in the differential diagnosis of axillary lesions, particularly if pain, paresthesias, or dysfunction exists in the distribution of a peripheral nerve, or if the mass is mobile in only a transverse direction. Preoperative magnetic resonance imaging may help delineate peripheral nerve sheath tumors in the axilla if the diagnosis is suspected. In addition, clear visualization of the mass is necessary before excision to prevent significant nerve injury. This approach should
avoid the inadvertent segmental resection that occurred in our patients. Interestingly, the upper extremity nerve most commonly affected by schwannoma is the median nerve (Fig 2, A), which was the nerve involved in both patients. If correctly diagnosed preoperatively or intraoperatively, schwannomas may be successfully enucleated from the involved nerve with minimal morbidity by simply isolating the lesion from the remainder of the fascicles and removing the affected fascicle and tumor (Fig 2, B). The use of optical magnification greatly facilitates this resection. Ninety percent of patients have an improvement or no change in preoperative symptoms after schwannoma excision, while the risk of postoperative neurologic deficit is only 4%.6 In the absence of symptoms, these tumors do not require surgical removal, though they are likely to continue to enlarge. These cases are presented as a cautionary note for any surgeon performing a routine excisional biopsy in the axilla. Schwannoma removal may be unnecessary if the diagnosis is made in time to prevent iatrogenic nerve injury. The consequences of inadvertently excising this tumor along with normal nerve fascicles, in contrast, is potentially devastating to the patient and difficult to correct. REFERENCES 1. Das Gupta TK, Brasfield RD, Strong EW, Hajdu SI. Benign solitary schwannomas (neurilemomas). Cancer 1969;24: 355-66. 2. Maiuri F, Donzelli R, Benvenuti D, Sardo L, Cirillo S. Schwannomas of the brachial plexus-diagnostic and surgical problems. Zentralbl Neurochir 2001;62:93-7. 3. Boutsen Y, DeCoene B, Hanson P, Deltombe T, Gilliard C, Esselinckx W. Axillary schwannoma masquerading as cervical radiculopathy. Clin Rheumatol 1999;18:174-6. 4. deSouza FM, Hudson AR. Surgical exploration of enlarged lymph nodes at the root of the neck. J Otolaryngol 1989;18: 112-5. 5. Kretschmer T, Antoniadis G, Braun V, Rath SA, Richter HP. Evaluation of iatrogenic lesions in 722 surgically treated cases of peripheral nerve trauma. J Neurosurg 2001;94:905-12. 6. Matejcik V, Benetin J, Danis D. Our experience with surgical treatment of the tumours of peripheral nerves in extremities and brachial plexus. Acta Chir Plast 2003;45:40-5.
From the Division of Plastic Surgery, Massachusetts General Hospital, and Harvard Medical School
SCHWANNOMA, A BENIGN TUMOR of schwann cells, produces a well-circumscribed, slowly growing lesion.1 Although usually painless, pain or deficit in the nerve distribution can occur. Because of its fixation within the body of the nerve, a schwannoma often is mobile in a transverse, but not longitudinal, axis. Diagnosis is facilitated by magnetic resonance imaging, which shows a homogeneous mass that has well-defined borders and is hypo-isointense in T1-weighted images and hyperintense in T2weighted images, reflecting the high lipid content present in myelin produced by these cells.2 Although schwannoma is the most common benign peripheral nerve lesion, nerve tumors comprise less than 5% of all upper extremity tumors. Schwannoma usually occurs in the forearm and hand, but cervical and axillary schwannomas have been documented.2,3 While nerve injury has been described after cervical node biopsy,4 iatrogenic nerve injury has not been reported after axillary node biopsy. Here we report 2 cases of median nerve transection after presumptive axillary lymph node biopsy for suspected malignancy. In both cases, the axillary mass was not a lymph node, but a median nerve schwannoma. CASE REPORTS Patient 1. A 34-year-old, right hand dominant female presented to a general surgeon with a several-week history of an enlarging, 1.5-cm, firm, mobile mass in her left axilla. The patient had a past medical history significant for asthma and depression. She smoked 1 pack of cigarettes daily, and her mother and 2 aunts had
Accepted for publication October 1, 2004. Reprint requests: Jonathan Winograd, MD, Massachusetts General Hospital, Division of Plastic Surgery, 15 Fruit St, Wang 453, Boston, MA 02114. E-mail: [email protected]. Surgery 2005;137:378-9. 0039-6060/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.surg.2004.10.007
378 SURGERY
died of breast cancer. The mass was diagnosed clinically as an enlarged lymph node. Fine-needle aspiration to rule out malignancy was nondiagnostic, and she underwent excisional biopsy. In the recovery room, the patient complained of numbness in her left hand, which was attributed to the local anesthesia. Five days postoperatively, the patient presented with an abnormal hand examination consisting of the inability to flex the interphalangeal joint of her thumb, oppose her thumb, or flex the proximal interphalangeal and distal interphalangeal joints of her index finger. The pathologic diagnosis of the excised axillary lesion was schwannoma. The patient was eventually referred to our plastic surgery division and was noted to have absent function of her median nerve clinically. At that point, a median nerve injury was suspected, and a nerve conduction study and electromyography were obtained. These tests demonstrated an absence of motor and sensory conduction in the median nerve. Three months after schwannoma excision, exploration of the median nerve was performed. Intraoperative nerve conduction studies across the affected area of the median nerve showed complete absence of conduction. A 5-cm gap of median nerve was replaced with scar (Fig 1, A). The neuroma was excised to healthy fascicles, leaving a total gap of 7 cm (Fig 1, B). Six cable nerve grafts were used to reconstruct the gap by using 33 cm of sural nerve in addition to the median antebrachial cutaneous nerve on the affected side (Fig 1, C). Two months after the median nerve reconstruction, tendon transfers were performed for the patient’s high median nerve palsy. Specifically, the flexor digitorum profundus of the index finger was transferred to the flexor digitorum profundus of the middle, ring, and small fingers. The brachioradialis was transferred to the flexor pollicis longus. Subsequently, the patient underwent opponensplasty with her extensor indicus proprius tendon. At her last follow-up appointment 8 months after her median nerve grafting, she has an advancing Tinel’s sign to the level of the elbow. Patient 2. A 33-year-old female treated for Hodgkin’s lymphoma at age 12 years presented with a several-week history of an enlarging right axillary mass. The mass was thought to be lymphadenopathy secondary to recurrent Hodgkin’s disease, and an excisional biopsy was performed. Postoperatively, the patient developed a com-
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Surgery Volume 137, Number 3
Fig 2. A, Median nerve schwannoma. B, Enucleation of schwannoma and involved fascicle. Fig 1. A, Five-centimeter length of median nerve injury after excision of schwannoma thought to be an enlarged lymph node. B, Seven-centimeter gap after neuroma excision. C, Reconstructed median nerve with sural and median antebrachial cutaneous nerve grafts. plete median nerve palsy and complete sensory deficit. The pathologic diagnosis again was schwannoma. The patient was referred to our plastic surgery division 3 years after her injury. Currently, she is weighing her options regarding the reconstruction. She is admittedly hesitant to undergo any more surgery.
DISCUSSION Lymphadenopathy is the most common cause of an axillary mass. Although most lymphadenopathy is due to a benign cause, biopsy often is indicated to rule out malignancy. In addition to lymphadenopathy, the differential diagnosis of an axillary mass includes lymphatic malformation, lipoma, cysts, hidradentitis suppurativa, or dermatofibroma. Schwanomma should be included in the differential diagnosis of axillary masses because schwannoma also has been reported in the axilla.2,3 In addition, schwanoma often is confused with other soft tissue masses, and inadvertent nerve biopsy may lead to permanent disability. Seventeen percent of peripheral nerve trauma is due to iatrogenic injury.5 Although injury to the spinal accessory nerve has been documented after cervical lymph node biopsy,4 nerve injury after axillary lymph node biopsy has not been reported previously. The 2 patients presented in this report had a high index of suspicion for axillary node lymphadenopathy due to neoplasia based on family and personal medical history. However, nerve tumors should be included in the differential diagnosis of axillary lesions, particularly if pain, paresthesias, or dysfunction exists in the distribution of a peripheral nerve, or if the mass is mobile in only a transverse direction. Preoperative magnetic resonance imaging may help delineate peripheral nerve sheath tumors in the axilla if the diagnosis is suspected. In addition, clear visualization of the mass is necessary before excision to prevent significant nerve injury. This approach should
avoid the inadvertent segmental resection that occurred in our patients. Interestingly, the upper extremity nerve most commonly affected by schwannoma is the median nerve (Fig 2, A), which was the nerve involved in both patients. If correctly diagnosed preoperatively or intraoperatively, schwannomas may be successfully enucleated from the involved nerve with minimal morbidity by simply isolating the lesion from the remainder of the fascicles and removing the affected fascicle and tumor (Fig 2, B). The use of optical magnification greatly facilitates this resection. Ninety percent of patients have an improvement or no change in preoperative symptoms after schwannoma excision, while the risk of postoperative neurologic deficit is only 4%.6 In the absence of symptoms, these tumors do not require surgical removal, though they are likely to continue to enlarge. These cases are presented as a cautionary note for any surgeon performing a routine excisional biopsy in the axilla. Schwannoma removal may be unnecessary if the diagnosis is made in time to prevent iatrogenic nerve injury. The consequences of inadvertently excising this tumor along with normal nerve fascicles, in contrast, is potentially devastating to the patient and difficult to correct. REFERENCES 1. Das Gupta TK, Brasfield RD, Strong EW, Hajdu SI. Benign solitary schwannomas (neurilemomas). Cancer 1969;24: 355-66. 2. Maiuri F, Donzelli R, Benvenuti D, Sardo L, Cirillo S. Schwannomas of the brachial plexus-diagnostic and surgical problems. Zentralbl Neurochir 2001;62:93-7. 3. Boutsen Y, DeCoene B, Hanson P, Deltombe T, Gilliard C, Esselinckx W. Axillary schwannoma masquerading as cervical radiculopathy. Clin Rheumatol 1999;18:174-6. 4. deSouza FM, Hudson AR. Surgical exploration of enlarged lymph nodes at the root of the neck. J Otolaryngol 1989;18: 112-5. 5. Kretschmer T, Antoniadis G, Braun V, Rath SA, Richter HP. Evaluation of iatrogenic lesions in 722 surgically treated cases of peripheral nerve trauma. J Neurosurg 2001;94:905-12. 6. Matejcik V, Benetin J, Danis D. Our experience with surgical treatment of the tumours of peripheral nerves in extremities and brachial plexus. Acta Chir Plast 2003;45:40-5.