Schwannoma of the penis: A case report

Abstract

Penile schwannoma is a rare tumor arising from the neurilemmal cells reported only a few in the literature. Here we report a case of penile schwannoma in a young adult treated successfully by local excision.

Resumen

Schwannoma del pene es un tumor poco común que surge de las células del neurilema, se han registrado solo unos pocos en la literatura. Aquí se presenta un caso de schwannoma del pene en un adulto joven tratado con éxito mediante extirpación.

Case report

A 21-year-old male presented with a painless lump on the radix of the penis which was first noticed 6 months ago and had enlarged slowly causing no symptoms except cosmetic deformity. On examination, 3 cm × 2 cm nodule on the radix of the penis was observed. The overlying skin was smooth and intact, however the depth of the invasion could not be determined. No penile deformity as well as sensory deficit was found. The rest of the genitalia was normal and no evidence of similar lesions was noted elsewhere.

Sonography revealed a well encapsulated mass to be located on the radix penis showing increased vascularity in the center of the lesion on color flow Doppler evaluation. Magnetic resonance imaging confirmed the sonographic findings revealing a mass very near to penile suspensory ligament (Fig. 1).

Figure 1.

Magnetic resonance image of the well-circumscribed mass and Surgical resection of the mass.

Surgical resection with careful dissection of the mass was performed (Fig. 1) which was confirmed by pathologic examination to be schwannoma. Grossly, the tumor was a well-defined, white 2.8 cm × 2 cm × 1.5 cm firm mass (Fig. 2). Histopathological examination described the mass as a characteristic mixture of Antoni A and Antoni B fibers. Immunuhistochemical study showed diffuse and strong positivity for S-100 protein which confirmed the diagnosis of schwannoma finally (Fig. 2)

Figure 2.

Gross appearance of the mass, A mixture of Antoni A areas with nuclear palisading and Antoni B areas (hematoxylin and eosin stain, 100×), Diffuse S-100 immunoreactivity in tumor cells (100×).

Discussion

Schwannomas are benign encapsulated nerve sheath tumors arising from the Schwann or neurilemmal cells. They can be found in any location but mostly arise in the head, neck, extremities, mediastinum, and retroperitoneum,¹ occuring at all ages but most common between 20 and 50 years old.² Schwannoma of the penis is an extremely rare entity and a few cases have been reported in the literature.^3–12

The differential diagnosis of penile schwannomas includes soft tissue tumors of the penis such as leiomyomas and neurofibromas and sarcomas which are rare.

Imaging studies such as ultrasonography and magnetic resonance imaging are nonspecific giving us limited information about the lesion but is valuable in narrowing the differential diagnosis.

Definitive diagnosis can only be made by pathologic examination. Histologically, the mixture of Antoni A and Antoni B areas, together with Verocay bodies is diagnostic for schwannoma.¹³ Strong S-100 protein staining is also supportive for the diagnosis.¹⁴

Surgical excision is the treatment of choice and usually curative. Local recurrence is extremely low.^3–7

Responsabilidades éticas

Protection of human and animal subjects

The authors declare that no experiments were performed on humans or animals for this study.

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The authors declare that they have followed the protocols of their work center on the publication of patient data.

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The authors have obtained the written informed consent of the patients or subjects mentioned in the article. The corresponding author is in possession of this document.

Conflict of interest

The authors declare no conflict of interest.