Neurofibroma

Inguinal hernias are a common cause of abdominal wall pain and are the most common abdominal wall abnormality. They can usually be differentiated from other abnormalities by history and physical examination. Occasionally, the diagnosis may be difficult with very small or very large lesions. The following case report describes an abdominal wall neurofibroma presenting as an inguinal hernia in a young, active duty, male soldier with previously undiagnosed neurofibromatosis.

Introduction

Inguinal hernias are commonplace among active duty soldiers. They constitute one of the leading causes of medical leave from work. It is estimated that 750,000 inguinal hernia repairs are performed in the United States annually.1 Almost one-half of these were performed on patients less than 40 years old.2 They constitute a relatively common cause of emergency department admissions. Therefore, other causes of abdominal wall bulges are considered less often. Nevertheless, lymphadenopathy, abscesses, and benign and malignant tumors must be excluded during the patient's evaluation.

Case Report

The patient was a 21-year-old, active duty, Caucasian man who initially presented to the emergency department with a bulge in the right groin. The patient first noticed the mass approximately 1 year previously and stated it had steadily grown in size. At the time of presentation, it was 13 × 6 cm in size. The patient complained of moderate discomfort with strenuous exercise like running and sit-ups but had no pain at rest. He did not notice a change in size during activity. He also noted no change in bowel or bladder habits and reported no difference in sexual function. He noted no other lesions elsewhere and felt well otherwise. By examination, the patient was felt to have a large inguinal hernia and he was subsequently referred for hernia repair on a routine consult.

On his initial consultation, the patient was queried about medical and surgical histories and family and social historiesall were noncontributoiy. By examination, the patient had an obvious bulge in the right groin (Fig. 1). This mass was irreducible, firm, and fixed to the abdominal wall. It was positioned obliquely in the right groin and extended into the inguinal canal near the pubis. No adenopathy was noted. The left groin was unremarkable. No ventral or femoral hernias were appreciated. A chest radiograph was performed. No acute or metastatic processes were noted. An abdominal and pelvic computed tomography scan was performed. A representative section is shown in Figure 2. An magnetic resonance imaging scan (data not shown) was performed, showing homogenous enhancement of the mass on T2 weighting.

After consulting with a surgical oncologist, the patient was taken to the operating room, and multiple core biopsies were obtained through a 5-mm skin incision. Care was taken to avoid traversing fascial planes during the procedure because of the risk of tumor dissemination or bowel injury.

Histologic examination revealed a plexiform neurofibroma. The patient was further queried specifically about personal and family history of neurofibromatosis. The patient denied personal history of the disorder but admitted to a positive history of neurofibromatosis in his father. He was subsequently referred to the regional referral hospital for definitive resection. The lesion was dissected off the spermatic cord and abdominal wall musculature without difficulty. However, the ilioinguinal nerve appeared to be encased by the mass. Therefore, it was transected and sent en bloc with the specimen. There was no gross evidence of malignant infiltration of surrounding tissues. It was not necessary to use prosthetic mesh to reconstruct the abdominal wall. The patient's postoperative course was uneventful, and he returned to light duty in 1 month. Pathologic examination revealed that the lesion was 14.0 × 5.0 × 2.5 cm. There was no evidence of neurofibrosarcoma. The final diagnosis was plexiform neurofibroma.

Discussion

Inguinal hernias are exceedingly common. However, this case had several findings that suggested that this was not a hernia. First, the patient had an obliquely positioned, hard mass that extended up to the iliac crest. Inguinal hernias may attain very large dimensions but usually present with the largest portion inferiorly near the pubic tubercle. Second, the mass was irreducible and did not change in size with exercise and the Valsalva maneuver. Although some hernias may be chronically incarcerated, many reduce partially and are not fixed to the abdominal wall musculature. Hernias may contain a number of viscera including in colon, bladder, small bowel, and omentum. In female patients, adnexal structures are prone to herniation. When these contents become incarcerated, this leads to tissue edema and eventually to vascular compromise (strangulation). However, the time frame from incarceration to strangulation is not known. Therefore, incarceration should be considered a surgical emergency. Clearly, morbidity is lower when hernias are repaired before strangulation occurs. Third, this patient had cafeau-lait spots (Fig. 1), suggesting the diagnosis of neurofibromatosis and abdominal wall neurofibroma. This was unrecognized until later in the patient's evaluation.

Neurofibromatosis is an autosomal dominant disorder with near complete penetrance but variable phenotypic expression.3 It occurs as two subtypes: neurofibromatosis type 1 (NF1) and type 2 (NF2). NF1 is the more common. Diagnostic criteria for NF1 include pigmentary lesions (cafe-au-lait macules, skin fold freckling, and Lisch nodules), neurofibromas, optic pathway gliomas, and bony dysplasias.4 Less common associations include gastrointestinal stromal tumors and vascular abnormalities like renal artery stenosis and coarctation of the aorta.5-7 NF2 is an autosomal dominant disorder that predisposes to central nervous system tumors. It is characterized by bilateral acoustic neuromas, eighth nerve palsy, neurofibroma, meningioma, glioma, schwannoma, and juvenile posterior subcapsular lenticular opacities.8

Plexiform neurofibroma is an uncommon but highly characteristic variant of neurofibroma. It occurs almost exclusively in patients with NF1 and it may occasionally undergo malignant degeneration.9 Currently, surgical extirpation is the only curative therapy. This may be challenging when these lesions occur in nerve roots and facial nerves because these tumors insinuate through foramina and encase other structures.4 In this case, the tumor presented as a discrete mass without an infiltrative component. Its location in the inguinal canal and presentation as a hernia documents an unusual presentation of this tumor and neurofibromatosis.

References

1. Safadi BY: Duh QY: Minimally invasive approaches to inguinal hernia repair. J Laparoendosc Adv Surg Tech A 2001; 11: 361-6.

2. Rutkow IM: Epidemiologie, economic, and sociologie aspects of hernia surgery in the United States in the 1990s. Surg Clin North Am 1998; 78: 941-51.

3. Pycha A, Klingler CH, Reiter WJ: Von Recklinghausen neurofibromatosis with urinary bladder involvement. Urology 2001; 58: 106.

4. Packer RJ, Gutmann DH, Rubenstein A, et al: Plexiform neurofibromas in NF1: toward biologic-based therapy. Neurology 2002; 58: 1461-70.

5. Seymour-Dempsey K, Andrassy RJ: Neurofibromalosis: implications for the general surgeon. J Am Coll Surg 2002; 195: 553-63.

6. Criado E, Izquierdo L, Lujan S, et al: Abdominal aortic coarctation, renovascular, hypertension, and neurofibromatosis. Ann Vasc Surg 2002; 16: 363-7.

7. Boldorini R, Tosoni A, Leutner M, et al: Multiple small intestinal stromal tumours in a patient with previously unrecognized neurofibromatosis type 1 : immunohistochemical and ultrastructural evaluation. Pathology 2001; 33: 390-5.

8. National Institutes of Health Conference: Neurofibromatosis 1 (Recklinghausen disease) and neurofibromatosis 2 (bilateral acoustic neurofibromatosis): an update. Ann Intern Med 1990; 113: 39-52.

9. King AA, DeBaun MR, Riccardi VM, et al: Malignant peripheral nerve sheath tumors in neurofibromatosis 1. Am J Med Genet 2000; 93: 388-92.

Guarantor; MAJ Craig G, Chang, MC USA

Contributors: MAJ Craig G. Chang, MC USA*[dagger]; David A. Provost, MD*; LTC Thomas LeVoyer, MC USA[double dagger]; LTC Richard W. Ellison, MC USA[double dagger]

* Department of Surgery, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9092.

[dagger] Department of Surgery, Bayne-Jones Army Community Hospital, Fort Polk, LA 71459.

[double dagger] Department of Surgery, Brooke Army Medical Center, 3851 Roger Brooke Drive, Fort Sam Houston, TX 78234-6200.

This manuscript was received for review in March 2003 and accepted for publication in June 2003.

Reprint & Copyright © by Association of Military Surgeons of U.S., 2004.

Copyright Association of Military Surgeons of the United States Mar 2004
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