Introduction

Soft tissue tumours of bone are infrequent in Orthopaedics practice. Therefore peripheral nerve sheath tumours are uncommon and mostly mistaken for Ganglion of the wrist and have diagnostic and treatment challenges.¹ PNSTs (Peripheral Nerve sheath tumors) are tumors of hand present as solitary swelling along the course of nerve with incidence of 5% of all tumors of upper extremity.² More common in females and have known to show association with Neurofibromatosis type 1.³ They usually grow slowly and appear as painless swellings for several years before diagnosed.⁴ Bony involvement is extremely rare, especially in the upper extremities⁵. Although the diagnosis is established with imaging in most of the cases, the gold standard for diagnosis still remains histopathological examination⁶

Case Report

A 67-year-old female presented to our OPD with swelling on her right wrist from last 6 months which was increasing gradually, over time for which took treatment at various hospitals. Regarding her family history, there were no reports of related systematic or neoplasm diseases. On clinical examination, swelling was firm, non-tender and no signs of inflammation were present and percussion over mass produced a Tinel-like sensation along median nerve. Neither motor weakness nor muscular atrophy was observed. Other laboratory findings were normal. For final excision, a longitudinal incision which was centred over sweeling was made, without releasing transverse ligament of carpal tunnel. The lesion was revealed in an eccentric position along median nerve. A marginal swelling excision with preservation of median nerve was done after careful surgical manipulations. After complete excision of mass, clear damage to distal ulna and radius was seen. The defect of bone and soft tissue was postoperatively protected with a forearm splint for six weeks and final diagnosis of PNST was made on basis of Histological report. On final follow up for last 6 months patient did not have any recurrence of swelling with complete movements at wrist joint

Discussion and Conclusion

Pathology behind Peripheral Nerve Sheath tumours of hand is not clear, most of these tumors are misdiagnosed as ganglion cyst.[1] Histopathological examination is the most important for diagnosis. Kubiena et al.[7] showed that these lesions arise from the cells of the nerve sheath and engulf some nerve fascicles. However, bone destruction due to a benign NF is not so common. This presentation of bone damage is commonly seen in schwannomas, neuromas, and malignant tumors.[8] The diagnosis of Peripheral nerve sheath tumor always remains a challenge and multiple differential diagnosis even after using MRI remains challenging and following tumors can be considered: begin solitary neoplasms such as lipomas, fibromas, xanthomas, ganglion tumors, mucous cysts, glomus tumors, giant cell tumors of the tendon sheath, vascular tumors, as well as post-traumatic neuromas, in addition to low-grade malignant neoplasms.[9] A challenging step in the treatment is the complete tumor excision and the simultaneous preservation of nerve function. On the other hand, wide local dissection is difficult in patients who presents with large masses which infiltrate the surrounding soft tissue and bone.[6]

Figure 6 and 7: Well-defined PD FS hyperintense/T1 hypointense lesion noted in the distal forearm with widening of distal radioulnar joint. The lesion is seen the dorsal and volar aspect of distal forearm traversing in between distal radius and ulna. Th lesion is displacing the triangular fibrocartilaginous complex caudally.

Figure 8: Intra operative Swelling Excision

Figure 9: Histopathological slide showing tumour cells with elongated nuclei in collagen rich matrix