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INTRODUCTION: Schwannoma is a benign, encapsulated neoplasm with an overall low incidence. It typically occurs in the head and neck regions and seldom develops in the scrotum. Histology shows 2 distinctive patterns (Antoni type A or type B) and several variants including cellular, ancient, glandular, and epithelioid. A 45-year-old male presented with a 1-year history of a painless, slowly growing, left-sided scrotal mass. Ultrasonography revealed an intrascrotal, extratesticular, soft-tissue mass without local invasion. The mass was successfully and totally excised without opening it and without remnant. Histopathology revealed an Antoni type A, cellular variant schwannoma of the scrotum.
Tarek A Salem
Urology Department, Suez Canal University, Ismailia, Egypt
Submitted July 20, 2010 - Accepted for Publication July 30, 2010
KEYWORDS: Schwann cell; Schwannoma; Neurolemmal sheath.
CORRESPONDENCE: Dr. Tarek Salem, Department of Urology, Suez Canal University, Faculty of Medicine, Ismailia 31911, Egypt ().
CITATION: UroToday Int J. 2010 Oct;3(5). doi:10.3834/uij.1944-5784.2010.10.02
A schwannoma is a benign, encapsulated neoplasm that is derived from the Schwann cells of the nerve sheath. The exact incidence of schwannoma is unknown, but these lesions are rare. Schwannomas can be found in all age groups, but they are more common in the first 4 decades of life and affect both sexes equally. On occasion, they may occur with neurofibromatosis or arise sporadically .
Schwannoma most commonly occurs in the head and neck region. Scrotal schwannoma is a rare neoplasm that poses a diagnostic challenge to urologists. The present report describes a rare case of scrotal schwannoma and reviews the current modality of investigation and treatment of this tumor.
A 45-year-old male presented with a 1-year history of a painless, slowly growing, left-sided scrotal mass. There was no history of surgical or medical problems, and there was no significant family history.
The mass was located medial and posterior to the left testis. It measured 2.5 cm x 2 cm. It was oval in shape, firm-to-hard in consistency, and completely separated from the left testis and spermatic cord. It was not attached to the scrotal skin or other underlying structures. There were no palpable inguinal lymph nodes.
Ultrasonography showed an oval, well-defined, soft tissue lesion located behind the left spermatic cord (Figure 1; Figure 2). The lesion measured 21.7 mm x 16.7 mm, with internal heterogeneous echogenicity. Both testes appeared to be normal. Figure 3 shows that the left testis was normal and not involved by the tumor.
Surgical exploration was done. The left-side scrotal compartment was opened by longitudinal incision that could be extended up or down according to the site of the tumor. Exploration revealed that the tumor was very deep, coming from the posteroinferior part of the scrotal septum. The oval mass was well encapsulated and yellow in color. It was not invading any surrounding structures and could easily be identified and isolated. The mass was successfully and totally excised without opening it and without remnant at the septum (Figure 4). No hemorrhage or other pathology was found at the surgical site.
After excision, the oval mass was cut into 2 pieces at midline by the surgeon. This revealed a tan interior color with a center of hemorrhage. The whole specimen was sent to histopathology. Results revealed a bisected, oval mass with a smooth, tan outer surface with areas of hemorrhage coloration. The mass measured 2.5 cm x 2 cm x 1.5 cm. Microscopic evaluation (Figure 5) showed an encapsulated schwannoma (neurilemmmoma) with edema, congestion, and areas of hemorrhage. There was no evidence of malignancy or attached tissue remnant from surrounding structures.
A follow-up evaluation completed 3 months after surgery revealed no recurrence of the tumor. The patient will be evaluated again at 6 months. He was also asked to report immediately any new swellings if they occurred anywhere on his body.
The microscopic appearance of schwannoma is distinctive, with no recognizable patterns. Antoni A areas are composed of compacted spindle cells that are often arranged in palisades or have an organized arrangement (Verocay bodies). Antoni B areas consist of tumor cells suspended in a myxomatous matrix that may appear microcystic. Several variants of schwannomas have been observed, based on appearances . These variants include cellular, glandular, epithelioid, and ancient types; all exhibit benign progression. Cellular types are almost exclusively composed of Antoni A areas but lack Verocay bodies; this is evident in the present case.
Although schwannomas are rare, most cases occur in the neck and head region (trigeminal nerve, facial nerve, vestibular nerve, vagus nerve, parotid, thyroid, vocal cord, floor of the mouth, orbit, and infratemporal fossa) . Other less common locations include the extremities, mediastinum, thorax , retroperitoneum , pancreas  and pelvis . Scrotal schwannomas have been infrequently described in the medical literature [7,8,9]. Chan et al  presented a case of a 28-year-old male with benign scrotal swelling. Surgical excision revealed ancient schwannoma of the scrotum.
Schwannomas pose a difficult diagnostic challenge to the urologist. Radiological findings are often nonspecific . Ultrasonography can differentiate between solid and cystic tumors. Either computed tomography (CT) or magnetic resonance imaging (MRI) can be helpful in determining the size, location, local involvement, and distant spread. Fine-needle aspirate (FNA) cytology is not often helpful. Tissue architectural information by either biopsy or excised specimen histology is the only gold standard diagnostic investigation.
Surgical excision has remained the mainstay of treatment. Although benign large or incompletely excised lesions are capable of recurrence, malignant change is exceedingly rare [3,10].
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