Intrascrotal non-testicular schwannoma: a rare case report.

Sir,

A schwannoma is a benign nerve sheath tumour composed of schwann cells, which normally produce the insulating myelin sheath covering peripheral nerves. It arises most frequently from the acoustic nerve. In the peripheral nervous system, it is usually found in association with one of the main nerves of the limbs, usually on the flexor aspect near the elbow, wrist or knee, the hands or the head and neck.[1] Schwannoma of the scrotum and testis though described in literature, it is very rare.[2] We herein, report a very rare and unusual case of intrascrotal non-testicular schwannoma.

A 24-year-old male presented with a history of slowly growing, right-sided scrotal swelling of 15 years duration having occasional tenderness. No similar swellings were appreciated elsewhere in the body and there was no other significant history or clinical findings. The physical examination revealed an oval, firm mass, measuring 3 cm Χ 2.5 cm in size at the root of the scrotum on right-side close to the testis [Figure 1]. The overlying scrotal skin was stretched, thinned out and showed telangiectasia. There was no inguinal lymphadenopathy. A provisional clinical diagnosis of skin appendageal tumour was considered.

Figure 1

An oval, firm mass, measuring 3 cm × 2.5 cm in size at the root of the scrotum on right-side close to the testis

On ultrasound examination, there was paratesticular scrotal mass with a scant amount of fluid collected within the tunica vaginalis. Both tests were normal.

The swelling was excised in to under local anaesthesia after informed consent. The specimen submitted for histopathological examination.

Histopathological report showed spindle shaped cells with poorly defined cytoplasm and elongated, wavy, basophilic nuclei. The nuclei were palisading and arranged in parallel rows with intervening eosinophilic cytoplasm in a typical appearance as Verocay bodies. The classical cellular Antoni A interspersed with myxomatous Antoni B areas are seen in Figures 2 and 3. The diagnosis of schwannoma was reported. This was further confirmed with immunomarker S100 positive staining. Thus, the final diagnosis of intrascrotal extratesticular schwannoma was reached.

Figure 2

Classical cellular Antoni A interspersed with myxomatous Antoni B (×10)

Figure 3

Spindle shaped cells with poorly defined cytoplasm and elongated, wavy, basophilic nuclei (×40)

Schwannomas arise from the cranial, spinal and the peripheral nerves of the body. It may involve many sites and the rare sites reported being face, neck, scalp, hands, tongue, palate and the larynx. Among all, the testicular schwannomas are the rarest.[2-4] Schwannoma in male genital system may involve testis, penis, spermatic chord, tunica vaginalis and prostrate.[56] Scrotal schwannoma may be testicular or non-testicular in origin. Most of them occur in young and middle aged adults.[7]

Clinically, schwannomas are round or oval, circumscribed nodules varying in size up to 5 cm, usually firm in consistency and tend to be asymptomatic; however, when they enlarge, they result in symptoms related to compression of the surrounding structures.[8]

Histologically, benign schwannoma are composed of an alternating pattern of Antoni A (highly cellular areas) and B areas (hypo cellular areas with myxoid change).[9] On electron microscopy tumour cells shows typical features of Schwann cells.[10] Immunohistochemistry shows strong and uniform staining with S100.[11]

Surgical excision is a mainstay of treatment. Recurrence after complete surgical excision is uncommon. Similarly, malignant transformation in a schwannoma is extremely rare.[12]

In the present case, the clinical suspicion was that of a skin appendageal tumour while the radiologic impression was that of a paratesticular tumour. The differential diagnosis of benign paratesteticular tumours includes leiomyoma, lipoma, fibroma or haemangioma.[13] There was no evidence of neurofibromatosis.

As far as our knowledge is concerned, this is the second case reported from India and only the seventh case of benign intrascrotal non-testicular schwannoma in the literature.[25141516171819]

We have reported this case for its rarity and to consider it as differential in the evaluation of scrotal swelling.