Nitya R. Ghatak

Remyelination in the Human Central Nervous System

Abstract. Remyelination, albeit incomplete, has been demonstrated in human central nervous system (CNS). However, information about the initial stage and the final extent of such remyelination is not available. We describe the morphologic findings of a demyelinating lesion with evidence of early remyelination in a biopsy obtained from a 15-year-old boy about two weeks after the onset of neurologic symptoms. The demyelinated area appeared hypercellular with a relatively large number of oligodendrocytes frequently seen in the process of new myelin formation. In addition to the usual reactive changes, the astrocytes were often seen to contain otherwise normallooking oligodendrocytes within their cytoplasm. In the ensuing months, the patient made apparently total functional recovery accompanied by nearly complete resolution of the white matter lesions demonstrated by the subsequent magnetic resonance studies. These observations suggested that the initial remyelination seen in the biopsy eventually succeeded in producing extensive remyelination in the lesion. Although the exact nature of the demyelinating disorder in our patient remains undetermined, this study indicates that clinically significant remyelination is possible in human CNS. Also, our findings appeared strikingly similar to those described in certain experimental animal models in which widespread remyelination is known to occur.

Further observation on the fine structure of a colloid cyst of the third ventricle

SummaryThe fine structure of a surgically excised colloid cyst is described. The cyst was lined by ciliated and nonciliated columnar cells. The nonciliated cells contained secretory material and had a surface coating. In addition, a third type of smaller cell was seen wedged between the columnar cells and abutting on the basement membrane. These cells contained abundant free ribosomes and tonofilaments and displayed well developed desmosomes and half desmosomes. The cyst lining closely resembled the upper respiratory epithelium rather than neuroepithelium, thus supporting the contention that colloid cysts are derived from an endodermal source.

Gliosarcoma With Cartilage Formation

A case of gliosarcoma with cartilaginous component is described. Immunohistochemical and electron microscopic studies confirmed the presence of glial and fibroblastic elements. A major part of the sarcomatous tissue was undifferentiated and not labeled by any of the markers used including those for endothelial cells. The cartilage cells also were not labeled either by antiglial fibrillary acidic protein or any other marker. The occurrence and histogenesis of cartilage in gliomas and gliosarcomas have been reviewed.

Neurofibrillary pathology in progressive supranuclear palsy

SummaryWe describe the fine structure of the subcortical neurofibrillary tangles (NFT) in 2 cases of progressive supranuclear palsy (PSP). In case 1 (69-year-old man) about one half of the NFT in the midbrain and pons examined were composed of 13–16 nm straight filaments and the others were made up of paired helical filaments (PHF) of Alzheimer type. The NFT in case 2 consisted of straight tubules with infrequent segments of unusual twisted fibril of unknown nature. The simultaneous occurrence of straight and PHF in one of these cases suggests that the NFT in PSP may be similar to those of Alzheimer type occurring in various conditions.

Xanthogranulomatous colloid cyst of the third ventricle

SummaryThis is a case report of a xanthogranulomatous colloid cyst of the 3rd ventricle. Posible etiologies for this rare entiry, along with the clinical problems that may be associated with it, and the differential diagnosis are discussed.

Malignant transformation of benign cerebellar astrocytoma

A patient who had a well‐differentiated cerebellar astrocytoma resected at 4 years of age, had glioblastoma multiforme of the cerebellum after a symptom‐free interval of 28 years. Late malignant transformation of a cerebellar astrocytoma of childhood is rare and previous cases are reviewed. Cerebellar astrocytomas are typically among the most benign of primary brain malignancies with excellent long‐term survival rates, sometimes with incomplete resection. This patient indicates that follow‐up needs to be long‐term because biologic behavior cannot be predicted fully in all cases.

The short-term effect of low-dose radiation on intracranial germinoma. A pathologic study.

A correlative pathologic and imaging (computed tomography and magnetic resonance imaging) study is reported of a pineal germinoma in a 35‐year‐old man who died unexpectedly of massive pulmonary embolism on the 8th day during the course of radiation therapy after receiving a total dose of only 1600 cGy. A histologic study of the entire lesion in serial sections revealed no viable tumor cells. The tumor bed was composed of stromal elements with a variable degree of proliferation. The lymphocytic component of the tumor was unaffected by the radiation. This case provided a rare opportunity to show total eradication of tumor cells in a germinoma after a small dose of radiation and supports the notion, based on imaging observations, that histologically proven intracranial pure germinomas may be treated successfully with a much smaller dose of radiation than previously thought.

Desmoplastic cerebral astrocytoma of infancy - A case report with immunohistochemical, ultrastructural and proliferation studies

We present a case of desmoplastic cerebral astrocytoma of infancy (DCAI) in a 7 1/2-month-old girl and include immunohistochemical, ultrastructural and proliferative activity studies. The dural-based cystic tumor showed a biphasic pattern consisting of glial fibrillary acidic protein (GFAP)-positive astrocytes embedded in a desmoplastic stroma. The astrocytic processes were lined with basal lamina at their surface contacting the collagen. Scattered islands of undifferentiated small cells were seen acquiring GFAP positivity at their peripheral zone facing the collagen. Studies with silver nucleolar organizer region and proliferating cell nuclear antigen disclosed a high proliferative activity. Flow cytometric study showed an elevated S phase and 15% hypertetraploid cell population. These findings contrast the favorable prognosis of the tumor at 26 months follow-up. Probably, extracellular-matrix-induced maturation of the undifferentiated cells with the formation of basal lamina may account for this unique disparity.

Light and electron microscopic observations on a ganglioneuroma

SummaryThis report describes some additional morphologic observations on a mediastinal ganglioneuroma. The neoplastic neurons contained argentaffin cytoplasmic granules presumably representing neurosecretory granules. Cytoplasmic inclusions resembling Picks bodies were frequently observed in the neuronal components of the tumor. These inclusions consisted of neurofilaments mixed with a variable number of microtubules, dense core vesicles and other organelles. These findings expand the range of conditions in which Picks bodies are found.

Spinal roots in Werdnig-Hoffmann disease.

SummaryThe spinal nerve roots were studied in two siblings with Werdnig-Hoffmann disease (WHD). An invasion by fibrous astrocytes was consistently seen along the atrophic ventral roots, more extensively in the older sibling. The parallel glial processes extended in discrete buadles and were always enclosed by a basal lamina. Loss of unmyelinated axons and probable glial extension along unmyelinated fibers were also seen. The astrocytic processes with abundant microtubules and prominent junctional devices resembled those of the subpial region, which appeared to have gained access into the ventral roots following axonal degeneration. The present observations suggest that such glial migration, although apparently unique in WHD, is a secondary phenomenon and fails to resolve the issue as to whether neuronal degeneration or an injury to the nerve roots is the primary event in this disorder.