Giant Invasive Sacral Schwannoma Showing Chromosomal Numerical Aberrations [-14,+18,+22]
A 58-year-old woman had a 6-year history of progressive left buttock pain radiating to the limb. The pain was aggravated by walking, while relieved by lumbar flexion. She had no history of antecedent trauma or constitutional symptoms. She had objective weakness of the bilateral extensor hallucis longs, graded as 4/5 by manual muscle testing. Sensory deficit was observed in the left S1-3 area. Deep tendon reflexes were preserved and were normal bilaterally at the knees and ankles. The patient had no fasciculation, atrophy, or upper motor neuron signs. No cutaneous stigmata of neurofibromatosis were observed.\nIn the computed tomography (CT) scans, a large mass was found in the upper sacrum (). Angiogram showed evidence of hypervascularity (). Magnetic resonance imaging (MRI) revealed a tumorous cystic lesion (9.5×8.0×4.5 cm) occupying most of the left upper sacrum. The cystic wall showed a hypointense signal on the T1-weighted images and a moderately high signal on the T2-weighted images. Homogeneous rim enhancement of the cystic lesion was observed following administration of gadolinium contrast (). A tru-cut bone biopsy determined a histological diagnosis of schwannoma.\nBilateral laminectomy (L4-S3) was performed using a posterior midline approach to expose the spinal canal. The cystic tumor was found to be firmly adherent to the arachnoid and nerve roots. Histopathological examination showed an Antoni A schwannoma (hypercellular) in most areas. The tumor cells were richly cellular but with a low mitotic count (). Smaller areas showed the presence of an Antoni B schwannoma (hypocellular). No anaplasia or necrosis was detected. Immunohistochemical staining showed strong expression of the S-100 protein and glial fibrillary acidic protein (GFAP) (). There was no evidence of nerve infiltration or mitoses to suggest malignancy. The tumor was confirmed as a giant invasive spinal schwannoma (GISS) composed of spindle cells with elongated, hyperchromatic nuclei and abundant cytoplasm.\nCytogenetic analyses were performed on primary cultures obtained from the first surgical sample. Standard culture and harvesting procedures described previously were utilized []. Karyotype designation was established in accordance with the International System for Human Cytogenetic Nomenclature 2009 []. Twenty cells were analyzed of which 8 cells represented an abnormal clone characterized by a chromosomal numerical aberration, 47,XX,-14,+18,+22 (). Ten cells showed various abnormal patterns, which were derived from -14, +18, or +22, where the remaining 2 cells were found to be normal female cells (46,XX).\nAlthough the tumor was incompletely excised, the patient was generally in good condition without disease progression for 3.3 years after surgery.