Native cephalic vein remains the superior dialysis conduit, even thirty years after it was first described. However, up to 37% of hemodialysis patients develop progressive stenosis in the venous circuit of arterio-venous fistula (AVF), which may later cause thrombosis and occlusion. To study the pre-existing morphological changes in the wall of the cephalic vein before AVF construction, we collected 23 cephalic vein specimens from 3 normal, young trauma and twenty renal failure patients. The samples were collected at the time of vascular repair in the first group and AVF construction in the second group. Sections were prepared and stained for both light and transmission electron microscopy (TEM) examination. Compared with normal cephalic vein, all pre-access cephalic veins showed thickening of the wall and intimal hyperplasia. Other changes were loss of internal elastic lamina in 9 (45%) patients, loss of endothelial cell layer in 6 (30%), inflammatory cell infiltration of the wall in 5 (25%), mural calcification in 3 (15%) and telangiectasia in 2 (10%). Other ultrastructural changes observed were intimal hypertrophy, degeneration and loss of the endothelial cells, degeneration and fraying of smooth muscle cells (SMCs) and loss of wall components into the lumen. In conclusion, most of the apparently normal cephalic veins of renal failure patients showed morphological abnormalities at the time of AVF construction, which may well influence the outcome of shunts in terms of future stenosis and failure. It seems likely that the later development of AVF stenosis may be the result of pre-existing disease rather than the direct insult of arterialization.

Innumerable carcinoid tumourlets may develop within pulmonary lobes should there be scarring from intralobar sequestration; these tumourlets may, in turn, be the cause of chronic lung disease. This report documents the incidental detection of multifocal carcinoid tumourlets in the lung of a 65-year-old man who had repeated episodes of lung infection, progressive dyspnea and haemoptysis; he lived at high altitude. The left lower lobe of the lung was resected surgically, during which procedure an aberrant systemic arterial supply was noticed. The patient had diffuse bronchiectasis and intralobar sequestration. The latter implies the development of abnormal lung tissue located within lobar tissue--but which does not communicate with the bronchial tree; it is supplied with arterial blood from a branch of the aorta--arising either above or below the diaphragm. There was loss of demarcation between the sequestered lung and the surrounding lower lobe lung parenchyma. The proliferation of pulmonary neuroendocrine cells in the form of tumourlets, had probably occurred as an adaptive response to the chronic hypoxia experienced. The combination of intralobar sequestration, bronchiectasis and carcinoid tumourlets, although uncommon, may arise when intralobar sequestration of the lung has not been resected at an incipient stage.

Malignant melanoma of soft tissue, also called clear cell sarcoma (CCS) of tendons and aponeuroses, presents as a soft tissue mass, usually in the lower extremity of young females. We report two cases of CCS of the upper extremity--in a Korean and a Saudi Arabian girl. Because of the presence of melanin, melanosomes, S-100 protein and the tendency for regional nodal metastases, it has been suggested that this entity be considered a melanoma rather than a soft tissue sarcoma. The evidence for a neuroectodermal origin of these neoplasms is compelling. Despite these features, CCS has been reported as showing a distinct chromosomal translocation pattern t(12;22)(q13;q12) in certain isolated cytogenetic or molecular diagnostic case reports; however, there is no information about the breakpoints at genomic level. Such genetic studies need to be performed on primary and metastatic cutaneous, mucosal or ocular melanomas prior to considering them specific for malignant melanoma of soft tissue/CCS. Microscopically, solid nests and fascicles of pale fusiform or cuboidal cells are divided by fine fibrous tissue septa. Characteristically, the cells possess a round to oval nucleus with a central prominent nucleolus. Pleomorphism may or may not be present; the cytoplasm is clear due to the presence of glycogen but, occasionally, the cytoplasm is more eosinophilic, resembling a melanoma. A tumour size (> or = 5 cm) and the presence of necrosis are statistically significant predictors of poor prognosis. A lesion on the proximal part of an extremity progresses slower than one that is more distal (i.e. acral). An early diagnosis and initial radical surgery are essential for a favourable clinical outcome. Once regional lymph node metastases or haematogenous dissemination has occurred, the prognosis becomes dismal.

Most malignant schwannoma are deeply situated, and some may arise from superficial neurofibromas. 1 Solitary tumors are more prone to recognition than those associated with neurofibromatosis because the histologic appearance resembles that of other sarcomas and sometimes undifferentiated carcinomas. 2 Electron microscopy or immunohistochemical studies are needed to confirm the diagnosis of malignant schwannomas. 3 The presentation and management of an extremely rare case of malignant schwannoma in the thyroid gland is reported.