br Conflicts of interest br Funding This study was

Conflicts of interest
Funding This study was supported by grants from the Ministry of Science and Technology, Taiwan (MOST-103-2314-B-002-090).
Introduction Ancient schwannoma is an uncommon variant of schwannoma, which arises from the nerve sheath Schwann cells, with a typically long course of growth. These tumors are termed “ancient” because of the degenerative features acquired as the tumor ages, such as cystic necrosis, hemorrhage, calcification, relative loss of Antoni type A tissue, and the presence of degenerative nuclei. These changes are believed to occur because it takes a long time for ancient schwannomas to develop. Schwannomas with these degenerative changes can be misdiagnosed as malignant sarcomas or other forms of soft-tissue neoplasms owing to the nuclear pleomorphism. Ancient schwannoma is usually located deeply in the head and neck, thorax, retroperitoneum, pelvis, and extremities of elderly patients. Spinal canal ancient schwannoma is very rare; there are only few reported cases in the literature. The most common symptom of a spinal schwannoma is pain, either localized or radicular, associated with frequent involvement of dorsal sensory nerve roots. Herein we report a case of thoracic spine intradural extramedullary ancient schwannoma in a schizophrenic patient who initially experienced severe back pain, which was misinterpreted as somatic delusion symptoms for an extended duration of time.
Case presentation Upon neurological examinations during his current ER visit, muscle power levels in the patient\'s lower limbs were only grade 1/5 in right side and grade 2/5 in left side. Increased deep tendon reflex, increased spasticity and positive Babinski sign were also detected in both lower extremities. Pinprick sensation decrease was further demonstrated below the T12 level symmetrically, and a thoracic spinal cord lesion was thereafter suspected. A subsequent magnetic resonance imaging (MRI) of the spine showed an intradural extramedullary cystic tumor at T9-T10 level with marked spinal cord tlr signaling (Fig. 1). Due to these findings, a T9, T10 laminectomy and tumor excision was then performed. We noted the presence of a well-defined yellow-grayish appearance cystic tumor attached to a nerve root (Fig. 2). The tumor was grossly total excised with the attached nerve root sacrificed. Subsequent pathology study showed spindle tumor cells with focal nuclear palisading, cystic change, hemorrhage and foamy cell infiltration. Nuclear degenerated atypia was also noted. The patient\'s immunohistochemistry workup also showed strong positive staining of S-100 protein (Fig. 3). After review of the results of both prior and current testing and physical examination, a diagnosis of ancient schwannoma was thus made.
Discussion Schwannomas or neurilemmomas are benign and slow growing tumors that arise from the peripheral nerve sheath Schwann cells. The tumor cells are arranged in varying cell proportions and arrays named Antoni type A and Antoni type B tissues. Antoni type A area is a compact array of spindle-shaped cells with high cellularity, while Antoni type B tissue is less cellular, with a predominantly loose matrix. When schwannomas demonstrate degenerative pictures including cyst formation, hemorrhage, calcification, diffused hypocellular areas (relative loss of Antoni type A tissue), and degenerative nuclei, they are termed “ancient” schwannoma. The nuclear degenerative features, characterized by nuclear hyperchromasia and pleomorphism, are thought to be the result of long-term tumor growth and aging. Immunohistochemically, these tumors also show diffuse positivity for S100 protein in the cytoplasm. This “ancient variant” is an uncommon subtype of schwannoma, which was first mentioned in the literature by Ackerman and Taylor in 1951 to describe schwannomas with calcification. For schwannomas, the most useful image tool for pre-operative diagnosis is MRI. Typical findings of ordinary schwannomas are a low signal on T1-weighted images, a high signal on T2-weighted images, and strongly enhanced by gadolinium contrast medium, which is the characteristic of the Antoni type A area. In contrast, degenerative cyst formation, hemosiderin deposition, and calcifications are the most useful radiological clues for ancient subtype. They also show different enhancing pattern, primarily enhanced in the circumference of the cyst, hematoma and tumor capsule, while illustrating the feature of Antoni type A tissue loss in the ancient variant. Focal areas of higher signal on T2-weighted image could also be seen in the cystic portions.