Investigation of Schwannomas in the Forearms, Hands, and Digits: A Retrospective Study

Background: Previous reports on schwannomas of the upper extremities have mainly focused on proximal involvement. This study aimed to evaluate pre- and peri-operative findings in schwannomas of the distal upper extremities and assess the accuracy of diagnosis and surgical outcome. Methods: We identified 24 patients with isolated tumors. Seven patients had schwannomas located in the forearm, eleven in the hand, and six in the digits. We collected the following data: preoperative clinical and magnetic resonance imaging findings, provisional diagnosis, surgical findings and procedures, tumor volume, and postoperative clinical findings. Data were compared between tumors of different locations. Results: The mean age of our cohort at the time of surgery was 48.0 years and the mean follow-up period was 10.6 months. All patients with forearm schwannomas were diagnosed preoperatively by the presence of the Tinel-like sign and suggestive magnetic resonance imaging findings. In contrast, schwannomas in the hands and digits often lacked these diagnostic features; only five patients with hand schwannomas and one with digit schwannoma were correctly diagnosed. Microsurgical enucleation was the most common treatment. Ten patients reported newly acquired paresthesia after operation, which resolved within the follow-up period in nine patients. Three of the four patients with preoperative paresthesia and one patient who underwent enucleation with surgical loupes still had paresthesia at the final follow-up. Conclusions: In schwannomas of the distal upper extremities, a more distal location is associated with a lower occurrence of the Tinel-like sign and fewer suggestive magnetic resonance imaging findings, resulting in lower diagnostic accuracy. However, intra-operative diagnosis is usually straightforward and microsurgical enucleation does not cause iatrogenic nerve deficit. When treating soft tissue tumors in the hand and digits that present without specific or suggestive findings, the possibility of schwannoma should be considered.