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.