# Pathological Fracture in the Metatarsal Bone Due to an Intraosseous Schwannoma: A Case Report

## TL;DR

A rare case of a benign tumor in the foot bone led to a fracture and highlights the need for thorough diagnostic methods.

## Contribution

This case report presents a rare intraosseous schwannoma in the metatarsal bone and emphasizes integrated diagnostic approaches.

## Key findings

- The tumor caused a pathological fracture in the first metatarsal bone.
- Radiological and immunohistochemical features were ambiguous, requiring combined diagnostic methods.
- The lesion was confirmed benign despite an elevated Ki-67 index.

## Abstract

Intraosseous schwannomas (IOSs) are uncommon benign tumors arising from nerve sheath cells. Schwannomas occurring in the metatarsal bones are extremely uncommon. This case report describes a young adult with a progressively enlarging mass in the foot, which led to limited mobility and ultimately resulted in a pathological fracture of the first metatarsal bone. Imaging studies revealed a diffuse, lytic lesion accompanied by surrounding soft tissue swelling. Histopathological evaluation confirmed the diagnosis of a schwannoma. Notably, this case highlights a key diagnostic challenge: its radiological and immunohistochemical features can be ambiguous. Although findings such as an elevated Ki-67 index suggested potential low-grade malignant transformation, retained H3K27me3 expression and an indolent clinical course confirmed the benign nature of the lesion. This case underscores the diagnostic complexity of ambiguous skeletal lesions and emphasizes the necessity of integrating clinical, radiological, and pathological assessments to achieve an accurate diagnosis and guide management. Reporting this case in the literature should help enhance awareness of rare variants of IOSs and advocate for the adoption of an integrated clinical-radiological-pathological workflow when managing ambiguous skeletal lesions.