An electron microscopic study of central nervous system sarcoidosis

Neurologic manifestations of sarcoidosis

Neurologic manifestations occur in more than 5% of sarcoidosis patients and may be the presenting feature. Neurosarcoidosis can manifest in a myriad of ways including: cranial neuropathy, aseptic meningitis, mass lesions, encephalopathy, vasculopathy, seizures, hypothalamic-pituitary disorders, hydrocephalus, myelopathy, peripheral neuropathy, and myopathy. Because its etiology is unknown, its neurological manifestations are so diverse, and its diagnosis cannot be readily confirmed by laboratory tests, neurosarcoidosis poses many clinical problems. The diagnosis of neurosarcoidosis is usually based on the identification of characteristic neurologic findings in an individual with proven systemic sarcoidosis as established by clinical, imaging, or histologic findings. Although corticosteroids are regarded as the foundation of treatment, they are not always successful and have serious side-effects. Moreover, some patients with neurosarcoidosis are refractory to conventional therapy, and approximately 5-10% die. Optimal management of patients with neurosarcoidosis benefits from an understanding of the broad clinical spectrum of neurosarcoidosis, appreciation of the ways to best confirm a diagnosis, and awareness of the full range of treatment options, including the use of alternative therapies such as immunotherapy.

Pathology of sarcoidosis

This article reviews the pathology of sarcoidosis that covers the general and systemic aspects of the disease. Macroscopic and microscopic descriptions of the disease process are given for selected organs.

Human immunodeficiency virus and papovavirus infections in acquired immunodeficiency syndrome: an ultrastructural study of three cases

A wide variety of neurologic conditions associated with the acquired immunodeficiency syndrome (AIDS) have been attributed to human immunodeficiency virus (HIV) infection of the central nervous system (CNS). Tissue samples from the brains of three patients with AIDS, diagnosed as having CNS toxoplasmosis on the basis of computed tomographic scans of the head, were studied by transmission electron microscopy. In two, HIV particles were observed budding from, in close association with, and in cytoplasmic vacuoles of mononuclear and multinucleated macrophages, but no other cell types. The patient with the greatest number of HIV particles also had large amounts of papovavirus (progressive multifocal leukoencephalopathy) in the nuclei of oligodendroglial cells and in the cytoplasm of astrocytes. These astrocytes often had atypical features at the light microscopic level. Following an initial biopsy that showed only HIV, primary CNS lymphoma was diagnosed by needle biopsy and confirmed at autopsy in a second case. A diagnosis of progressive multifocal leukoencephalopathy was rendered by transmission electron microscopy in a third case, but no HIV was detected. Toxoplasmosis was not confirmed in any of the three cases. Diagnosis of CNS lesions in patients with AIDS should not rely exclusively on radiography but include biopsy for both light and transmission electron microscopy. Transmission electron microscopy can be employed to reveal HIV and papovavirus infections not discernible at the light microscopic level and should be used as a diagnostic tool in HIV-related infections.

Subplasmalemmal linear density: a mesodermal feature and a diagnostic aid

Subplasmalemmal linear density (SLD), a surface structure known to occur on mononuclear phagocytes, has been considered a possible morphologic marker of mesenchymal cells or cells of mesodermal origin. A retrospective review of human surgical pathology cases studied in a diagnostic electron microscopy laboratory over a five-year period confirmed that SLDs are primarily seen in cells of mesodermal origin in a variety of neoplastic and nonneoplastic tissues. Therefore, SLD may be of value as a mesodermal marker in evaluating poorly differentiated tumors. Furthermore, the presence or absence of SLD in tissue histiocytes in diverse conditions may contribute to the understanding of heterogeneity among this group of cells.