Brain tumours in childhood in Bombay: I: Histopathology showing changing patterns; II: Tissue culture with light and electronmicroscopy, stressing ingestion & degradation of bacteria by glial cells in vitro.

The pathological pattern of 86 brain 'tumours' in childhood during the years 1981-85 (out of a total of 586 for all ages), showed a higher proportion of neoplasms and a much lower of tuberculomas compared to the preceding three decades. A large number of histologically unusual cases was revealed. Through tissue culture of brain tumours we carried out morphological, histochemical and fine structural study of the tumour cells in vitro. The abundant presence of lysosomal acid phosphatase, in outgrowing cells, correlated with the detection of lysosomal dense bodies and vacuoles in araldite sections, by light and electronmicroscopy. In view of the phagocytic propensity of schwann cells for M. leprae as the important factor in leprous neuritis, TC preparations of gliomas, (in addition to acoustic schwannomas and meningiomas), were inoculated with two mycobacteria, M. scrofulaceum and the ICRC bacillus. There was a pronounced intracytoplasmic uptake, i.e. endocytosis, of acid-fast bacilli by the growing cells of these tumours. This was confirmed by electronmicroscopy which showed intact and degrading bacilli in various stages, in such cells of a typical cerebral astrocytoma used as an illustrative case in this paper. Ingestion and Digestion appear to be an inherent property of growing tumour cells in vitro. Fine structural examination of in vitro growth of an unusual subependymal giant cell astrocytoma, not inoculated with bacilli, served as a control. Cells of both tumours showed copious autophagic activity and cytoskeletal features of developing microtubules and filaments.

Pathology and pathogenesis of predilective sites of nerve damage in leprous neuritis. Nerves in the arm and the face.

A very brief review of the literature on the clinicopathological aspects of leprosy is given; mainly through references. The salient features of the two main types of leprosy--tuberculoid and lepromatous--are presented in a Table. The surgical and pathological findings are briefly described and the pathogenesis of involvement of the facial nerve (a motor nerve) is discussed. On the basis of (i) the severe histopathologic changes (degeneration) of the most distal part of the zygomatic branch of the facial nerve (innervating the orbicularis oculi), with sparing of the roots of all branches and the trunk of the nerve; (ii) the concurrent loss of cutaneous sensations in the territory of the maxillary division of the trigeminal nerve (the region of the zygoma and the lower eyelid); and (iii) the close approximation or even anastomoses occurring between the ultimate branches of these two nerves, it is postulated that paralysis of orbicularis oculi occurs secondarily to the sensory nerve damage, i.e. due to spread of infection from the sensory branches of the trigeminal to the motor branches of the facial nerve. The surgical and pathological findings of the nerves in the arm, especially the ulnar and the median and their branches are described, in tuberculoid and lepromatous leprosy. The forms of nerve degeneration, the occasional axon regeneration, and the role of the Schwann cell in harbouring the bacilli, are illustrated. The lysosomal enzyme activity in the Schwann cells of nerve fibres, particularly of unmyelinated fibres which preferentially phagocytose the M. leprae, and their role, albeit not very successful, in degrading the bacilli and controlling the infection, are also stressed, through light and electronmicrographs. The constellation of secondary factors of the terrain operating to produce further damage to primarily diseased nerves, is discussed. These factors include indirect compression from unyielding fibroosseous tissues, minor traumata, stretching of the nerves, and their exposure to lower temperatures in subcutaneous tissues.

Striated muscle in four categories of leprosy. II. Fine structural changes.

Fine structural changes are described in 21 muscle biopsy specimens from patients with early and established tuberculoid or treated and untreated lepromatous leprosy. The predominant light microscopic finding on paraffin sections of atrophy of the muscle fiber was confirmed in semithin araldite sections, which also revealed considerable degenerative changes in a few or more fibers. These were more clearly seen in ultrathin sections, especially in the lepromatous muscle specimens. The degeneration was in the form of severe loss or disorganization of the myofibrillar elements and in the most affected muscle fiber, a loss of all sarcoplasmic constituents, with occasional accumulation of lipofuscin in lysosome-like bodies. Only 3 of the lepromatous specimens showed 1 and 2 bacilli each, only 1 being within a muscle fiber. There were also mural changes in the small intramuscular blood vessels with proliferation of their basement membrane and pericytes. The mean serum IgG level in lepromatous patients was significantly elevated. This, together with the vascular change, might perhaps be responsible for the degenerative change in the muscle fiber despite a paucity of M. leprae in the muscle.

Lepromatous leprosy as a model of Schwann cell pathology and lysosomal activity.

A brief illustrated account is presented of the light microscopic pathology, histochemistry of lysosomal enzymes, and fine structural changes in the nerves of patients with untreated or treated lepromatous leprosy. Predominant bacillation of the Schwann cells of unmyelinated fibres, degeneration of their axons, prominence of phagolysosomes, and disappearance of these cells with endoneurial collagenosis were observed on electronmicroscopic examination of the index branch of the radial cutaneous nerve. Although there were changes in the blood vessels and proliferation of perineurium, bacillation of endothelial or perineurial cells was much less conspicuous. Intact and degenerating forms of M. leprae were found in both treated and untreated patients, fragmenting or crumpled forms being more frequent in the treated. Both groups of patients also showed increased lysosomal enzyme activity, evidenced by single or paired paranodal spots of acid phosphatase and beta-glucuronidase in Schwann cells in histochemical preparations of the nerve. There was lesser activity, and activity in fewer cells, in the case of beta-glucuronidase than of acid phosphatase. Diffuse beta-glucuronidase activity was found in the wall of empty-looking oval chambers in the Schwann cells, and acid-fast bacilli were seen in these chambers. In teased fibre preparations, both axonal degeneration and segmental demyelination were found. In semi-thin araldite sections, the myelinated fibre density was either preserved or reduced; large diameter fibres were more frequently depleted, with tall peaks of smaller fibres seen on plotting diameter spectra.

Culture and phagocytic characteristics of Schwann cells in vitro. A possible model substrate for cultivation of M. leprae.

Tissue cultures of five acoustic and four spinal schwannomas demonstrated good growth and migration of Schwann cells within two to four days. Two types of cells corresponding to Antoni type A tissue and Antoni type B tissue were clearly recognized. Both these cell types showed avid phagocytosis when the cultures were inoculated with mycobacteria, either ICRC bacilli or M. leprae. The phagocytic index was 95% at the end of two hours. The Schwann cells grown in vitro also showed intense acid phosphatase reaction with Gomori's stain, suggesting lysosomal activity. Neither this nor any phagocytosis was evidenced by fetal fibroblasts cultured similarly. Cells from two spinal neurofibromas grew and migrated slowly in vitro and were mainly fibroblasts.