Subsarcolemmal accumulations of abnormally shaped mitochondria

What it means

An abnormally increased number of mitochondria in the cytoplasma adjacent to the sarcolemma (muscle cell membrane), whereby the mitochondria also possess an abnormal morphology.

This finding can be demonstrated by electron microscopy. This finding is typical of mitochondrial myopathies.

Rare diseases that can present with this1

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