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Abstract  A rare but distinctive variant of smooth muscle tumours that occurs almost exclusively in the uterus is characterised by the presence of plexiform tumourlets, which are composed of clumps and cords of tumour cells that form a discrete pseudoepithelial component. We report on a case of a primary leiomyosarcoma of the proximal humerus, which, in addition to characteristic histological and immunophenotypic features of leiomyosarcoma, contained plexiform tumourlets. Tumour cells in the plexiform component focally expressed muscle/smooth muscle actin, calponin and cytokeratin. Spindle-shaped and epithelioid smooth muscle tumour cells also expressed the above antigens. This is the first report of a plexiform smooth muscle tumour arising in bone. This case is remarkable, not only for being only the second reported case of a malignant plexiform smooth muscle tumour, but also for being one of very few examples of this type of tumour arising outside the uterus; it also is unique in having arisen in a male patient. This variant of primary leiomyosarcoma needs to be distinguished from other bone tumours containing epithelial elements, notably metastatic carcinoma. [ABSTRACT FROM AUTHOR]

Abstract??Osteoblastoma rarely occurs in the scapula, and toxic osteoblastoma is a very rare subtype of this bone-forming tumour. This report details the clinical, radiological and pathological features of a toxic osteoblastoma of the scapula; it is the first reported case to be diagnosed correctly pre-operatively and treated appropriately by excision. [ABSTRACT FROM AUTHOR]

Abstract??We report on a case of a 36-year-old lady who presented with large, painful soft-tissue swellings of both Achilles tendons. MRI demonstrated fusiform enlargement involving the Achilles tendons bilaterally. The tendons returned heterogeneous signal intensity characterised by a diffuse reticulated appearance. The right tendon mass was treated with a wide marginal excision and Achilles tendon reconstruction. The histology confirmed Achilles tendon xanthoma. Further metabolic investigation revealed the patient to have a rare autosomal recessive condition called cerebrotendinous xanthomatosis (CTX). Her brother was also affected. CTX is easily treatable if diagnosed early, and should be suspected in patients presenting with bilateral Achilles tendon xanthomas and normal plasma lipid levels. [ABSTRACT FROM AUTHOR]

Hypoxia is known to act as a general stimulator of cells derived from marrow precursors. We investigated the effect of oxygen tension on the formation and function of osteoclasts, the cells responsible for bore resorption, which are of promonocytic origin. Using 7- and 13-day cultures of mouse marrow cells on ivory discs, we found that reducing oxygen tension from the ambient atmospheric level of 20% by increasing the proportion of nitrogen caused progressive increases in the formation of multinucleated osteoclasts and resorption pits. Peak effects occurred in 2% oxygen, where stimulations of resorption up to 21-fold were measured. Significant stimulations of osteoclast formation and resorption were observed even in severely hypoxic cultures gassed with 0.2% oxygen. Short-term cultures of cells disaggregated from rat bones indicated that hypoxia did not alter the resorptive activity of mature osteoclasts, but reduced their survival or adherence. In 3-day organ cultures of mouse calvarial bones, exposure to 2% oxygen resulted in maximal, fivefold stimulation of osteoclast-mediated calcium release, an effect equivalent to that of prostaglandin E2 (PGE2), a reference osteolytic agent. Hypoxia also caused a moderate acidosis in calvarial cultures, presumably as a result of increased anaerobic metabolism; this observation is significant because osteoclast activation is dependent on extracellular acidification. Our experiments reveal a previously-overlooked mechanism of considerable potential importance for the regulation of bone destruction. These findings may help explain the bone loss associated with a wide range of pathological states involving local or systemic hypoxia, and emphasize the importance of the vasculature in bone. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]