This is a hydrophilic polymer embolus with surrounding giant cell reaction. Hydrophilic polymers are ubiquitous on intravascular devices, used to decrease friction and the chance of damage to the vessel wall. However, separation of this material from the medical device has been documented to result in polymer embolization in a variety of organs. Histologically, it’s generally described as an amorphous or serpiginous basophilic substance with concurrent foreign body reaction. Here’s a comprehensive review on the topic.
With regard to the differential diagnosis, heart worm (Dirofilaria) is primarily a zoonotic parasite; however, humans can also be infected (but are suboptimal hosts) . When humans acquire the disease from a mosquito bite, the dying worms generally end up in the small pulmonary arteries, producing multifocal granulomas. Most cases are thought to be subclinical, though a minority may present with hemoptysis, fever, or a pleural effusion. It’s primarily an intravascular disease… so its presence in the myocardium (like in the question’s photo) would be unlikely. This article provides additional details.
Loa loa is another parasite that is transmitted by the deerfly. Disturbingly, this parasite can create visual movement across the surface of the eye, and sometimes under the skin. It has rarely been associated with heart disease but could potentially cause peripheral eosinophilia that could results in endomyocardial fibrosis.
Amyloid is an extracellular, amorphous eosinophilic material; in contrast to this basophilic, serpiginous substance.
Basophilic degeneration is a compelling choice because of the color of this substance. However, this is an age-related phenomenon resulting in globular basophilic deposits within cardiomyocytes (not giant cells), that are strongly PAS-positive (see image).
- Melanie Bois
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