Schwannoma of the interdigital nerve of the 1st space : About a case and review of the literature

Introduction : Schwannoma is a benign tumor caused by the proliferation of Schwann cells, and it is the most common tumor of the peripheral nerves. It is an encapsulated lesion that rarely causes neurological deficit, usually presenting as a painless mass, and treatment by excision of the lesion yields excellent results. We report a case involving the interdigital nerve of the first space, and discuss the clinical and therapeutic aspects of this localization. Observation : We present the case of a 50-year-old woman who developed a mass in the first digital commissure of the left hand that had been evolving for 2 years and was progressively increasing in volume. The clinical examination revealed a 5 cm swelling, soft, adherent to the deep plane, mobile relative to the superficial plane. The rest of the examination did not show any other localizations. The MRI confirmed the presence of an oval tissue formation, with regular well-defined contours, measuring 40×31×30 (H, W, AP) mmIt encompasses the radial artery of the index finger and the palmar digital nerve of the thumb. An excision was performed, revealing a capsulated, eccentric, multilobed tumor located on the interdigital nerve of the first space. The resection was macroscopically complete, with no involvement of the nerve continuity. Postoperatively, the patient showed no hypoesthesia or motor deficit. The histopathological examination concluded a benign schwannoma. Currently, 6 months post-surgery, the patient shows no signs of recurrence. Discussion : Schwannoma is a benign tumor of the peripheral nerves, usually solitary, affecting adults of both sexes, primarily involving the large nerve trunks of the upper limb. Although most schwannomas are painless, they can sometimes cause local pain, paresthesia, and rarely paralysis. The tumor is often discovered when a palpable mass is detected. In cases of multiple schwannomas, neurofibromatosis should be considered. These tumors often present with distal radicular pain, and MRI is the key exam for diagnosis, revealing an off-center nerve mass. The definitive diagnosis is histological, and treatment consists of surgical excision. Complete excision is possible in the majority of cases due to the off-center location of the tumor. The prognosis is generally favorable, with a low recurrence rate. Conclusion : Peripheral nerve tumors that can be excised, such as schwannomas, regardless of their location, are characterized by an excellent prognosis following appropriate surgical treatment that preserves the nerve fascicles. The persistence of symptoms after enucleation should prompt the search for other localizations.