Mucoid extracellular matrix accumulation

What it means

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.).

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.

Rare diseases that can present with this2

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Cystic medial necrosis of the aorta · MEMA