Clinical, Radiological, and Histological Characteristics of Intraosseous Schwannoma: Case Series of a Rare Benign Neoplasm of Bone

Abstract Schwannomas of intraosseous location represent an extremely rare clinical presentation of a benign bone neoplasm originating from Schwann cells. Its rarity and the broad spectrum of possible differential diagnoses render intraosseous schwannoma diagnostically challenging. Currently, only scattered evidence is available in the literature. We aimed, therefore, to summarize our clinical experience with this rare histological entity. A retrospective clinical chart review was performed, and seven patients with an intraosseous schwannoma were identified, including six female and one male patient. The mean age of included cases was 42 years (range: 17–58). In four patients (57%), the axial skeleton was affected, of which three cases involved the spine and one case involved the acetabulum. The other three cases of intraosseous schwannomas were located in the lower extremity, with one case in the distal femur, one case in the distal tibia, and another case in the distal fibula, respectively. Spinal presentation was invariably associated with large extraosseous components. In all cases, a biopsy was performed. All included patients were symptomatic and underwent surgical removal of the tumor. Histology from biopsy and surgery matched in all cases and confirmed the diagnosis of an intraosseous schwannoma. Intraosseous schwannomas show a considerable heterogeneity in clinical presentation, patients' age, and tumor location. Combined with its rarity, diagnosis can be challenging and warrants a multidisciplinary approach with orthopaedic surgeons, radiologists, and pathologists. The diagnosis is incumbent on the combined radiological and histological appearance. Indication for surgical removal is guided by the patients' symptoms and the risk of impending fracture.