No abstract

Intramedullary spinal cord neoplasms are rare, accounting for about 4%10% of all central nervous system tumors. Despite their rarity, these lesions are important to the radiologist because magnetic resonance (MR) imaging is the preoperative study of choice to narrow the differential diagnosis and guide surgical resection. On contrast materialenhanced MR images, intramedullary spinal tumors almost always manifest as expansion of the spinal cord and show enhancement. Syringohydromyelia and cystic lesions are frequently associated with intramedullary tumors. Nontumoral cysts tend to be located at the poles of the tumors and do not enhance on contrast-enhanced MR images, whereas cysts within the substance of the tumor are considered tumoral cysts and typically demonstrate peripheral enhancement. Spinal cord ependymomas are the most common type in adults, and cord astrocytomas are most common in children. Both entities constitute up to 70% of all intramedullary neoplasms. A central location within the spinal cord, presence of a cleavage plane, and intense homogeneous enhancement are imaging features that favor an ependymoma. Intramedullary astrocytomas are usually eccentrically located within the cord, are ill defined, and have patchy enhancement after intravenous contrast material administration. Even with these characteristics, it may not be possible to differentiate these two entities on the basis of imaging features alone. Cord hemangioblastomas are the third most common type of intramedullary spinal tumor. Gangliogliomas commonly extend over more than eight vertebral segments. Paragangliomas and primitive neuroectodermal tumors have an affinity for the filum terminale and cauda equina. Other spinal cord tumors include metastatic disease, which is characterized by prominent cord edema for the size of the enhancing portion, and primary lymphoma.

Sinus histocytosis with massive lymphadenopathy, also known as Rosai-Dorfman Disease (RDD), is an idiopathic histiocytic proliferation affecting lymph nodes. Although extranodal involvement has been reported in diverse sites, central nervous system (CNS) manifestation, particularly in the absence of nodal disease is uncommon. We report 11 cases of RDD primary to the CNS without evidence of other sites of involvement. The cases included 7 males and 4 females ranging in age from 22 to 63 years (mean: 41 y). The patients presented with headaches, seizures, numbness, or paraplegia. Eight cases involved the cranial cavity and three cases, the spinal canal. Lesions were most often extra-axial and dura based. Only one presented in the CNS parenchyma. Histologically, the lesions consisted of variable numbers of pale-staining histocytes with emperipolesis often overshadowed by extensive lymphoplasmacytic infiltrates and fibrosis in the background. Special stains for organisms were negative. By immunohistochemical analysis, the characteristic histiocytes were positive for S100 protein and CD68 and negative for CD1a. Treatment consisted of surgical biopsy or excision. Follow-up, available for 10 cases with intervals ranging from 5 days to 42 months (mean: 15 mo), disclosed one patient dying of operative complications 5 days after biopsy and nine patients with no evidence of disease progression RDD should be considered in the differential diagnosis of inflammatory lesions of the CNS. Our study suggests that this entity may have been misdiagnosed in the past as plasma cell granuloma or inflammatory pseudotumor.

Childhood ataxia with diffuse central nervous system hypomyelination syndrome (CACH) is a recently described leukodystrophy of unknown etiology. To characterize the neuropathological features and gain insight as to the pathogenesis of this disorder, we studied cerebral tissue from six patients with the CACH syndrome. Evaluation of toluidine blue-stained, semithin sections of white matter from CACH patients disclosed unusual cells with "foamy" cytoplasm, small round nuclei and fine chromatin. Electron microscopy (EM) revealed cells in the white matter with abundant cytoplasm containing many mitochondria and loosely clustered, membranous structures, but lacking the lysosomal structures seen in macrophages. Further analysis of tissue sections with antibodies and special stains demonstrated that the abnormal cells with abundant cytoplasm labeled with oligodendroglial markers, but did not react with macrophage or astrocytic markers. Double immunolabeling with macrophage and oligodendroglial markers clearly distinguished macrophages from the "foamy" oligodendroglial cells (FODCs). Proteolipid protein (PLP) mRNA in situ hybridization demonstrated PLP mRNA transcripts in a high proportion of oligodendrocytes in CACH patients compared to control patients, and PLP mRNA transcript signal in cells, morphologically consistent with FODCs. Normal and pathological brain control tissues did not contain FODCs. These neuropathological findings will be useful pathological identifiers of CACH, and may provide clues to the pathogenesis of this disorder.

Central nervous system (CNS) solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms recognized less than a decade ago. Approximately 60 cases of SFT have been reported in the central nervous system. We describe three atypical SFTs of the CNS, two intracranial and one within the spine. One intracranial SFT arose from the sella turcica and expanded into the suprasellar areas. It relapsed twice during the 3 years following partial resection, and the MiB 1 labeling index steadily increased without obvious malignant transformation. The second SFT arose from the confluence of the sinuses, widely invaded the lateral sinus and adjacent bones, had a low MiB 1 index and has not recurred after 5 years. The intraspinal tumor occurred at T5-T7 in a patient with multiple café-au-lait spots, was predominantly myxoid and developed a second similar lesion at S3-S5 14 years later. The MiB 1 index was lower in the second tumor. Immunohistochemistry confirmed that all were SFTs. These atypical presentations gave us an opportunity to provide further information about the natural histological course of CNS SFTs.