How to salvage a salvage endoprosthesis.

Custom-made endoprostheses can be linked to existing well-fixed implants in the treatment of complex periprosthetic femoral fractures. By adopting this salvage approach, secure implants can be retained in favour of patients undergoing more tissue disruptive procedures such as total femoral replacements. In this piece, we present a unique case illustrating a salvage strategy for treating a failed cement-linked salvage endoprosthesis, a complex scenario which to our knowledge has never before been reported

Extraskeletal Ewing’s Sarcoma Arising from the Sciatic Nerve: A Diagnostic Challenge

Ewing’s sarcoma is a common bone tumour of childhood but is a rare occurrence in individuals over 20 years of age. Few cases are reported as originating from peripheral nerves. We present an unusual case of extraosseous Ewing’s sarcoma originating from the sciatic nerve in a 66-year-old patient which had the clinical hallmarks of a benign nerve sheath tumour. Following discussion at a multidisciplinary meeting, excision biopsy of the suspected benign nerve sheath tumour was planned. At operation, the mass had malignant features. Histology confirmed the presence of Ewing’s sarcoma. Due to the morbidity of nerve resection, radiotherapy and chemotherapy were commenced. Ewing’s sarcoma is known to mimic benign pathologies. In this case there were subtle signs of a malignant process in the form of unremitting pain. It is vital to keep in mind the less common tumours that can affect the peripheral nervous system in such cases

Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain

<p>Abstract</p> <p>Background</p> <p>Human retinoic acid teratogenesis results in malformations of dorsally derived hindbrain structures such as the cerebellum, noradrenergic hindbrain neurons and the precerebellar system. These structures originate from the rhombic lip and adjacent dorsal precursor pools that border the fourth ventricle roofplate. While retinoic acid synthesis is known to occur in the meninges that blanket the hindbrain, the particular sensitivity of only dorsal structures to disruptions in retinoid signalling is puzzling. We therefore looked for evidence within the neural tube for more spatiotemporally specific signalling pathways using an in situ hybridisation screen of known retinoic acid pathway transcripts.</p> <p>Results</p> <p>We find that there are highly restricted domains of retinoic acid synthesis and breakdown within specific hindbrain nuclei as well as the ventricular layer and roofplate. Intriguingly, transcripts of cellular retinoic acid binding protein 1 are always found at the interface between dividing and post-mitotic cells. By contrast to earlier stages of development, domains of synthesis and breakdown in post-mitotic neurons are co-localised. At the rhombic lip, expression of the mRNA for retinoic acid synthesising and catabolising enzymes is spatially highly organised with respect to the <it>Cath1</it>-positive precursors of migratory precerebellar neurons.</p> <p>Conclusion</p> <p>The late developing hindbrain shows patterns of retinoic acid synthesis and use that are distinct from the well characterised phase of rostrocaudal patterning. Selected post-mitotic populations, such as the locus coeruleus, appear to both make and break down retinoic acid suggesting that a requirement for an autocrine, or at least a highly localised paracrine signalling network, might explain its acute sensitivity to retinoic acid disruption. At the rhombic lip, retinoic acid is likely to act as a dorsalising factor in parallel with other roofplate signalling pathways. While its precise role is unclear, retinoic acid is potentially well placed to regulate temporally determined cell fate decisions within the rhombic lip precursor pool.</p

Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain-3

Ough the cerebellar region (black dashed line in A) shows expression in the blood vessels within the neural tube (arrow) and the cranial mesenchyme (*). . Transverse section through the rostral hindbrain (white dashed line in A) reveals expression at the rhombic lip (inset at higher magnification).. Meningeal membrane expression at e7.5 (*). . Transverse section through cerebellum at e7.5 (black dashed line in D) shows meningeal, vascular expression. . Transverse section through e7.5 rostral hindbrain (white dashed line in D) showing expression in the meninges (*) and blood vessels.<p><b>Copyright information:</b></p><p>Taken from "Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain"</p><p>http://www.biomedcentral.com/1471-213X/7/138</p><p>BMC Developmental Biology 2007;7():138-138.</p><p>Published online 19 Dec 2007</p><p>PMCID:PMC2266733.</p><p></p

Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain-6

Mplex patchwork of hindbrain domains, including a dense, lateral column of expression within rhombomeres 5 and 6 (white arrow). . Locus coeruleus (arrow) and ventricular zone (*) in transverse section (at level indicated by black arrow in A). . Transverse section through the caudal hindbrain (indicated by dashed line in A) showing expression in discrete patches of proliferating cells. . Transverse section through rhombomere 5 (white arrow in A) reveals expression in both the ventricular layer and within post-mitotic neuronal populations. . Distinct longitudinal patterns of expression are maintained at e5. . Lateral view of e5 cerebellum and midbrain with locus coeruleus expression (arrow). . Ventral view of mid-hindbrain domain of an e5 embryo showing expression in the region of the isthmo-optic nucleus (arrowhead). . Expression at e7.5 assumes a defined rostrocaudal pattern incorporating the cerebellum, with the caudal limit at the level of rhombomere 6 (white arrow). . Ventricular expression in a transverse section (indicated by dashed white line in H) within the cerebellum. . Transverse section through caudal hindbrain (indicated by white arrow in H) showing expression in ventricular layer and pial membrane (pia, arrow).<p><b>Copyright information:</b></p><p>Taken from "Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain"</p><p>http://www.biomedcentral.com/1471-213X/7/138</p><p>BMC Developmental Biology 2007;7():138-138.</p><p>Published online 19 Dec 2007</p><p>PMCID:PMC2266733.</p><p></p

Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain-2

Ch (white arrow) and the isthmus (white arrowhead). . view of the dissected isthmus (arrow) showing a ring of expression, weakening at its dorsal apex. . Expression at the isthmus (arrow) and otic vesicle (white arrow) at e6. . Transverse section through isthmic region (dashed line in C) shows expression concentrated in bilateral foci within the isthmus. . Transverse section through the presumptive inner ear shows in the endolymphatic duct (white arrow) and saccule (white arrowhead).<p><b>Copyright information:</b></p><p>Taken from "Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain"</p><p>http://www.biomedcentral.com/1471-213X/7/138</p><p>BMC Developmental Biology 2007;7():138-138.</p><p>Published online 19 Dec 2007</p><p>PMCID:PMC2266733.</p><p></p

Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain-4

region (black dashed line in A). lies outside the ventricular layer. Dorsally, apparent ventricular expression is a by-product of the plane of section. . Transverse section through the hindbrain (white dashed line in A) with the rhombic lip indicated (arrow).. Dorsal view of an e6 embryo. . Transverse section through the cerebellum (black dashed line in D). . Transverse section through the caudal hindbrain (white dashed line in D) shows expression in the magnocellularis and underlying laminaris of the vestibuloacoustic nuclei, as identified by [65] (inset). . expression at the level of the cerebellum at e5 is expressed throughout the neural tube. Areas of lower expression correspond to descending axon tracts. . expression at the same axial level is ubiquitous but conspicuously elevated in the locus coeruleus, identified by the expression of or (inset). . in transverse section is uniformly expressed throughout the neural tube. . In caudal hindbrain, is elevated in a discrete column of neurons close to the pial surface.<p><b>Copyright information:</b></p><p>Taken from "Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain"</p><p>http://www.biomedcentral.com/1471-213X/7/138</p><p>BMC Developmental Biology 2007;7():138-138.</p><p>Published online 19 Dec 2007</p><p>PMCID:PMC2266733.</p><p></p