Cystic medial necrosis Medial degeneration Mucoid extracellular matrix accumulation 2013-06-13T12:55:22Z An increase of medial mucoid extracellular matrix creating translamellar and/or intralamellar expansions including extracellular pools as noted on an H&E stain and/or a stain to highlight extracellular matrix material (Movat's pentachrome, Alcian blue, etc.). SNOMEDCT_US:45894003 Cystic medial necrosis of the aorta UMLS:C0392775 MEMA replaces a variety of terms used in the past such as cystic medial necrosis, cystonecrosis, cystic degeneration, mucoid degeneration which, while generally understood by pathologists, are inaccurate. This histopathology can be subclassified and graded according to distribution, severity, and/or whether it crosses over multiple lamellar units as described. The grading should be reported as mild/moderate/severe and the distribution should be reported as focal, multifocal, or extensive. HP:0200146 MEMA SNOMEDCT_US:42182000 SNOMEDCT_US:234021009