Pathology cases – Mitochondrial calcification in a cardiac microinfarction


This case was originally posted as an unknown.  The consensus of folk who got back to me is that this is an uncommon degenerative process in a microinfarction where the mitochondria calcify, leading to the appearance of multiple faint blue dots in an area of myocyte necrosis.  Apparently it is more commonly seen in microinfarctions associated with catecholamines (e.g. stress cardiomyopathy, ingestion of sympathomimetics such as methamphetamine).

This is the case of a teenager found dead in bed in the morning.  He had been complaining of a URI the evening before.  At autopsy, he doesn’t have much going on.  A little pulmonary edema R&L lungs 710 and 530 grams),   The heart was a little big at 430 grams with mild LV dilation.  Tox is negative. Viral culture positive for rhinovirus.  Bacterial cultures were taken at three locations (first hospital, referral hospital, ME office).  All three were positive, but all three grew multiple different organisms, with no overlap between labs.

At autopsy, he had one odd finding — these areas in the myocardium.  I usually take 8 sections of heart (posterior lv, lateral lv, anterior lv, ivs, rv, avn, san x2).  These areas were sparsely found in all of the LV sections.

Here’s an overview:



Here’s a closeup of one area:

Here’s a GMS:

Here’s Gram:

Here’s trichrome:

It’s not a yeast like .  I thought for a minute it might be trympanosomiasis, but it really doesn’t look like Chaga’s disease either (those bugs tend to be in mini intracellular cysts).   But I have never had a case of Chaga’s disease, so I don’t have experience to fall back on, and I don’t feel confident in ruling it out.  Unfortunately, the lab we use found my postmortem specimen to be unsuitable for antibody testing (as so often happens with postmortem testing).  Is this just some sort of degeneration artifact?

I found one small area in the myocardium with lymphocytes:

After hearing from commenters and folk on a mailinglist, it seems this is a microinfarction with a somewhat unusual pattern of karrhyorexis.  Even though this is more commonly seen in catecholamine exposure, there was no history of drug use, and toxicologic evaluation was negative.  In the presence of a URI and positive viral cultures, I ended up diagnosing viral myocarditis, even though I would have preferred to see more inflammation.  It’s as much a diagnosis of exclusion as anything else.

5 thoughts on “Pathology cases – Mitochondrial calcification in a cardiac microinfarction”

  1. Trichrome has a contraction band necrosis look to it, but that isn’t readily apparent in the H&E and other stains. Odd geographic look to it considering the normal appearing myocytes around it. I don’t know if I have seen a degeneration artifact like that before in heart sections that I have looked at. Did you run cardiac genetics?

  2. I had a recent case of this – one of the pathways for myocardial infarction degeneration is through karyorrhexis and subsequent calcification. I thought I maybe had toxoplasmosis, but I showed it to a cardiac pathologist who confirmed that it was a normal, albeit rare, pathway for myocardial infarction degeneration. Basically the mitochondria die and calcify leading to many small calcifications that end up looking exactly like what you have! He also interestingly told me this pathway is more common in younger people (generally kids) and rat models!

    Long story short definitely microscopic infarct with a less common degeneration pathway!

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