Tram Track Appearance
Bone A descriptor for the split cortical thickening with parallel neo-osteogenesis or endosteal splitting, seen in infarctions of long bones in sickle cell anaemia
Brain A descriptor for the parallel calcified enhancement of cortical vessels seen in tuberous sclerosis—Sturge-Weber syndrome—due to calcium and iron deposition seen on a skull film
Lung A descriptor for the parallel, thickened bronchial walls seen on a plain film in bronchiectasis
Ophthalmology A finding described in optic nerve sheath meningioma, which outlines the normally sized nerve
Pathology Tram track appearance refers to parallel thickening and splitting of the glomerular capillary basement membrane due to subendothelial deposition of immune complexes, mesangial matrix and neutrophilic debris between the glomerular basement membrane and the vascular endothelium causing a double contour by light microscopy, a classic finding in type I, less in type II membranoproliferative glomerulonephritis and cryoglobulinemia; it is best seen by silver and PAS stains; the outer ‘track’ of the double contour corresponds to the original basement membrane, which is continuous and easily recognised; the inner basement membrane ‘track’ is discontinuous and of variable thickness. Cf Crescent formation
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.