Malignant nerve sheath tumour arising in a benign ancient schwannoma.

A malignant nerve sheath tumour arising in a longstanding benign schwannoma in a 75-year-old woman is described. Malignant change of this kind is extremely rare; there appear to be only four convincing previously reported cases.

The femoral head in osteonecrosis. A quantitative study of osteocyte population.

The occurrence of osteonecrosis following renal transplantation is well recognised but its pathogenesis remains unknown. We have quantified the number of empty osteocytic lacunae in the subchondral bone of femoral heads from a control group of patients, and compared these with femoral heads from a group of renal transplant recipients without evidence of overt osteonecrosis. There is a significant increase in empty osteocytic lacunae in renal transplant patients. We conclude that loss of osteocytes precedes other manifestations of osteonecrosis.

Neuropathology of the brain in HIV infection.

The brains of 26 patients infected with the human immunodeficiency virus (HIV) were examined post mortem. All patients were men, aged 20-67 years (mean 38.8). 13 (50%) were homosexual, 3 (12%) were bisexual, 8 (31%) were haemophiliac, 1 was both an intravenous drug addict and homosexual, and 1 denied belonging to any risk group. Only 3 (12%) brains were normal, whereas 23 (88%) showed abnormalities that varied in severity and complexity. 11 were affected by more than one disease. In addition to neoplasms, opportunistic infections, and vascular lesions, 6 cases of HIV encephalitis were found, characterised by multinucleate giant cells which indicate the presence of HIV. Microglial-macrophage nodules (nodular encephalitis) occurred in 5 cases. Cerebral pathology differed between risk groups: all 6 patients with HIV encephalitis were homosexuals, whereas vascular lesions were more common in haemophiliacs. These observations have fundamental implications for clinical practice and indicate the importance of neuropathological examination in AIDS.

Early avascular necrosis of the femoral head. Report of a case and review of the literature.

The clinical and pathological findings in a case of early avascular necrosis of the femoral head following renal transplantation are described. Regions of subchondral bone distant from the principal lesions showed increased numbers of empty osteocytic lacunae. This has been quantified and it is suggested that a loss of osteocytes is perhaps one of the earliest lesions leading to established avascular necrosis.

Measurement of total resorption surface in iliac crest trabecular bone in man.

Total resorption surface has been measured under ordinary light and polarized light in trabecular iliac crest bone from 57 healthy subjects and 40 patients with privational or malabsorption metabolic bone disease. Results obtained with the two methods were similar, although values for total resorption surface measured under polarized light were usually lower than those obtained under ordinary light in both groups of subjects studied. This most likely reflects the greater accuracy in the microscopic identification of resorption surface under polarized light.

Histomorphometric analysis of dynamic parameters of trabecular bone formation in the iliac crest of normal British subjects.

Some dynamic parameters of bone formation in trabecular iliac crest bone have been measured in a group of normal British subjects of both sexes over a wide age range. There was a significant age-related decrease in mean wall thickness. When either double plus single or double only tetracycline-labeled surfaces were used to represent actively mineralizing surfaces, there was a significant age-related decrease in the bone formation rate at the basic multicellular unit level. Osteoid maturation period showed a significant age-related increase when calculated using double plus single labeled surfaces. There was no significant change with age in fractional labeled surfaces, mean osteoid seam width, bone formation rate at tissue level, or bone formation period. The mean osteoid seam width and osteoid maturation period were significantly higher in males than in females.

Histomorphometric analysis of bone biopsies from the iliac crest of normal British subjects.

Bone histomorphometric parameters have been measured in a group of normal British subjects of both sexes over a wide age range. There is loss of trabecular mineralized bone volume with advancing age and an increase in osteoid volume and in the trabecular bone surface covered by osteoid seams. There was no change in the mineral appositional rate or in bone resorption surfaces.

Osteomalacia after small-intestinal resection.

Histological examination of bone from 25 patients with small-intestinal resection showed that 9 (36%) had osteomalacia, which was severe in 5 and mild in 4. The serum-alkaline-phosphatase concentration was raised in all patients with severe osteomalacia, but serum calcium, phosphate, and alkaline-phosphatase concentrations were normal in the 4 patients with mild disease, 2 of whom had symptoms. Osteomalacia was diagnosed radiologically in only 3 patients. Osteomalacia appears to be commoner in patients with small-intestinal resection than has previously been thought, and bone biopsy is essential if all cases are detected. Although high-dose parenteral vitamin-D therapy is usually effective in the treatment of osteomalacia after small-intestinal resection, our findings showed that oral vitamin-D metabolites and their analogues may also be effective. This has important practical advantages.

The pathology of renal ischaemia.

Examination of ischaemic kidneys reveals changes which generally correlate well with the pathophysiology of renal ischaemia. Although there is an association between renal ischaemia, juxtaglomerular granulation and hypertension, notable exceptions are seen from time to time. Improved methods of identification of the contents of juxtaglomerular granules may provide better methods of prediction of those patients likely to benefit from nephrectomy for hypertension associated with renal ischaemia. Further studies of the function of mesangial cells and of the smooth muscle cells of the juxtaglomerular apparatus promises to provide information to explain the collapse of glomerular tufts, and hence of impaired glomerular filtration, following ischaemia.

Immunoglobulin deposition in membranous glomerulonephritis: immunofluorescence and immuno-electron microscopy findings.

In a series of 250 renal biopsies (transplants excluded) the diagnosis of membranous glomerulonephritis was made in 22. This was done on light microscopy in 17, while the addition of immunofluorescence enabled the diagnosis to be made in a further five. Electron microscopy confirmed the diagnosis in all cases. Immunoperoxidase studies emphasized the basement membrane distribution of the deposits of immunoglobulin and relative sparing of the mesangium. They showed at an ultrastructural level the presence of IgG in the deposits.

Recurrent haematuria: role of renal biopsy and investigative morbidity.

The usefulness of renal biopsy in investigating unexplained haematuria was assessed by a study of 33 adults referred consecutively with this syndrome. Unequivocal abnormalities were seen on light microscopy or immunofluorescence in 31 of the 33 specimens of renal tissue examined. In 18 patients deposits of IgA were present in the mesangium. Loin pain occurred in only two of the 18 patients with mesangial IgA deposits, compared with 11 of the 15 patients without these deposits. Seven of the nine women in this series had had loin pain compared with only six of the 24 men. Thus a woman with loin pain and haematuria was not likely to have mesangial IgA nephropathy but this was found in 14 of the 18 men with unexplained painless haematuria. Failure to appreciate the role of renal biopsy in the investigation of unexplained haematuria may result in unnecessary radiology, considerable morbidity, and even in unjustified nephrectomy.

Renal damage caused by gentamicin: a study of the effects on renal morphology and urinary enzyme excretion.

Gentamicin sulphate was administered to male Wistar rats by intramuscular injection at varying dosage and for varying periods. At high dosage (50-100 mg/kg/day) gentamicin causes tubular necrosis. At dosages equivalent to that given to man (5 mg/kg/day) obvious degenerative changes are produced. Similar changes are seen in human tubular epithelium and urine deposits of patients treated with gentamicin. There is increased excretion of urinary enzymes proportional to the degree of tubular damage. The importance of these changes in man is stressed.

Evidence of gentamicin nephrotoxicity in patients with renal allografts.

Renal damage was assessed by measuring urinary enzyme excretion in 180 patients with renal allografts. Thirty-six of these patients were studied during 53 courses of treatment with antimicrobial agents which was the only antimicrobial agent which was associated with an increase in urinary enzyme activity. There was usually also evidence of reduced renal function. Renal morphological changes similar to those produced by gentamicin in rats were observed in human allograft biopsy specimens obtained during gentamicin treatment.