Pathologic observations that differ from those previously reported.

<p>Pathologic observations that differ from those previously reported.</p

Thrombi in coronary artery aneurysms (CAA) of KD patients.

<p>A. A CA already severely compromised by SA/C-LMP is virtually occluded by a superimposed fresh thrombus (dark red) that blends into the SA/C-LMP. Trichrome stain, case 18, original magnification 16×. B. Part of a NA CAA occluded by a fresh thrombus. There is a small area of organizing thrombus. Since only mildly inflamed fibrotic adventitia remains, it is not possible in this section to distinguish between NA and SA/C as the etiology. H&E, case 11, original magnification 10×. C. A small portion of CAA thrombus. The vascular granulation tissue has a loose matrix containing few free RBC, spindle cells and mononuclear cells, a few of which are macrophages containing brown hemosiderin blood pigment. Spindle cells are reaching into the luminal RBCs. H&E, case 22, original magnification 63×. D. The oldest peripheral thrombus in this CAA is re-canalizing. There are superimposed fresher thrombi. Since the CAA still has some remaining media, the aneurysm likely resulted from severe SA/C pan-arteritis. H&E, case 37, original magnification 10×. E. This organized SA/C CAA thrombus has peripheral clumps of calcium. Some of the media is still visible (upper right). H&E, case 19, original magnification 16×. L=lumen, LMP=luminal myofibroblastic proliferation, M=media, ADV=adventitia, ORG=organizing thrombi, R=recanalized, Ca=calcium, V=vessel.</p

Myocarditis.

<p>A. Low magnification H&E of a poorly-preserved hourglass-shaped epicardial CA showing varying degrees of SA/C peri-arteritis, transmural SA/C, and minimal preserved media. H&E, case 1, original magnification 10×. B. Perivascular and transmural SA/C inflamed adventitia and heavily damaged media with some discernible SMC and IEL, and SA/C-LMP with scattered pleomorphic myofibroblasts. There are some eosinophils intermixed with the small lymphocytes. H&E, case 1, original magnification 16×. C. A higher magnification of a typical area of SA/C-LMP with prominent amphophilic myofibroblasts in a background of mostly small lymphocytes, scattered eosinophils, and likely macrophages in a fibrillar ECM that shows some artifactual spaces. H&E, case 1, original magnification 25×. D. A typical area of the highly edematous interstitial myocarditis especially rich in eosinophils, with scattered lymphocytes, macrophages, and plasma cells. Note the longitudinally-sectioned caterpillar-shaped and cross-sectioned, owl eye-shaped (unidentified) Anitschkow chromatin pattern in a myocyte and two unidentified cell nuclei, respectively. H&E, case 1, original magnification 40×. L=lumen, NV=nerve, IEL=internal elastic lamina, Eo=eosinophil, AM=Anitschkow myocyte, MF=myofibroblast, V=vein, ADV=adventitia, M=media.</p

Increase in myofibroblast RER and pleomorphism, as well as intercellular elastin.

<p><b>A</b>) The actin (A)/dense bodies (long red arrows) share the cytoplasm with RER. The extracellular matrix is composed almost exclusively of haphazardly arranged electron dense banded collagen. The ECM obscures the dense plaques and external lamina. Pinocytic vesicles (P) are visible. Case 32, original magnification 5,000×. <b>B</b>) Dense plaques (short black arrows), actin (A), and dense bodies (long red arrows) have decreased and there is more RER. Note the abundant electron dense intercellular elastin (E), mixed with the collagen. Note the external lamina (long black arrows). Case 32, original magnification 5,000×.</p

Kawasaki Disease Vasculopathy, Process 1, Necrotizing Arteritis (NA).

<p>NA is an acute self-limited, one-time, synchronous process complete within about 2 weeks of fever. It starts at the endothelium of medium sized muscular and elastic arteries and progresses peripherally; involvement of veins, pulmonary arteries, and aorta is not observed.</p

Newly described pathologic features observed in the 41 KD patients.

<p>Newly described pathologic features observed in the 41 KD patients.</p

Pathologic findings in patients with Kawasaki Disease.

<p>RCIA=right common iliac artery, SA/C=subacute/chronic inflammation, CA=coronary artery, CAA=coronary artery aneurysm, LMP=luminal myofibroblastic proliferation, MI=myocardial infarction, TX=transplant, Mac=macrophage, SI=small intestine, RCA=right coronary artery, LAD=left anterior descending artery, LCx=left circumflex artery, IMA=inferior mesenteric artery, GB=gallbladder, MV=mitral valve, TV=tricuspid valve, PV=pulmonary valve, GT=granulation tissue, eos=eosinophils, SMA=superior mesenteric artery, PA=pulmonary arteries, macs=macrophages, PMNL=predominantly neutrophils, U=unknown, N/A=not available, EFE=endocardial fibroelastosis, ECMO=extracorporeal membrane oxygenation, IVC=inferior vena cava. Notes: CA sections usually contained myocardium, epicardium, and some endocardium. All patients had active SA/C plus LMP in coronary and also in available non-coronary arteries. Varying degrees of chronic hypoxia (hydropic change) seen in all cases. Anitschkow cells always seen, if case had at least two sections of myocardium. EFE always seen, if specimens included more than focal endocardium. By report=slides not available, but description sufficient to derive pathology.</p

Potential clinicopathologic outcomes following infection with the KD etiologic agent.

<p>Potential clinicopathologic outcomes following infection with the KD etiologic agent.</p

Copious cytoplasmic RER and shed external lamina and fibronectin.

<p><b>A</b>) The slightly tangentially sectioned cell has about equal RER and actin (A) with dense bodies (long red arrows). There is a single large primary lysosome (*), shed external lamina (short red arrows), and relatively sparse dense plaques (short black arrows). Case 13, original magnification 5,000×. <b>B</b>) A MF with more RER than peripheral actin (A)/dense bodies (long red arrows). The nucleus is large and irregular with a prominent nucleolus and apparently lost some chromatin during processing. Shed external lamina (short red arrow) and fibronectin (long black arrow) are prominent. Case 13, original magnification 4,000×.</p

Kawasaki Disease Vasculopathy, Process 3: Luminal Myofibroblastic Proliferation (LMP).

<p>A process triggered locally and apparently remotely by Process 2 that can progress to total occlusion. LMP myofibroblasts are ultrastructurally, but not functionally, similar to wound healing myofibroblasts.</p