Hydrophilic Polymer Embolus (HPE) Vasculopathy of the Lung
Julia M Choi, Rashi I Mehta, Allen P Burke, Rupal I Mehta. University of Maryland Medical Center, Baltimore, MD; State University of New York Upstate Medical University, Syracuse, NY
Background: Hydrophilic polymers are commonly applied as coating on endovascular device surfaces and have the potential to strip off within the bloodstream during use in patients, causing hydrophilic polymer emboli (HPE). Recent reports document cardiovascular complications with associated morbidity and mortality in rare patients. The focus of this study was to evaluate the histologic features and tissue responses to HPE involving the lungs.
Design: Ten cases of pulmonary HPE were retrospectively reviewed (2010-2012). Hematoxylin and eosin, Masson trichrome, and elastic-stained sections of formalin-fixed, paraffin-embedded tissue were evaluated. The study incorporated 7 autopsy cases; 2 lung explants (including 1 retransplanted explant); and 1 wedge biopsy. The mean patient age was 56 years (age range: 22 to 73 years); 7 patients were male.
Results: Histologic appearances of actively biodegrading HPE were extremely variable. In all cases, lamellated granular basophilic material, consistent with polymer, was identified within small-to-medium sized vessels in peripheral lung. Seven of these cases showed localized involvement, while the remaining three showed diffuse dissemination with involvement of multiple lobes. Affected vessels ranged from 13 to 1280 μm in diameter (average: ∼150 μm). The total number of HPE ranged from 1 to 430 per case (average: ∼80 microemboli). Tissue responses included vascular occlusion (n=10); intravascular fibrocollagenous change (n=7); microthrombus formation (n=5); hemorrhage (n=4); recanalization (n=2); infarction (n=2), and diffuse alveolar damage (n=1). Inflammatory changes included intra- and peri-vascular mononuclear (n=10), neutrophil (n=6), and foreign body giant cell (n=5) reaction; granulomatous change (n=3); microabscess formation (n=2), and vasculitis (n=2). None of the cases were correctly diagnosed at the time of prospective review.
Conclusions: Hydrophilic polymer emboli are characterized by variable histologic appearances and cause significant pathologic changes when deposited in pulmonary vessels. This vasculopathy represents a newly recognized disease associated with modern interventional therapies. A heightened clinical awareness of this iatrogenic complication may lead to more accurate and timely diagnosis in affected patients.
Monday, March 4, 2013 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 287, Monday Morning