The pathognomonic feature of rheumatic heart diseaseis

The Anitschkow cell or caterpillar cell is a modified histiocyte which is called so because of its ribbon like wavy chromatin when seen on longitudinal section. On transverse section, “owl’s eye” nuclei are seen. They, along with plasma cells and lymphocytes, constitute an Aschoff nodule seen classically in the myocarditis of rheumatic heart disease (may also be seen in endocarditis and pericarditis). McCallum plaques are formed due to regurgitant jets from mitral valve into the left atrium due to endocarditis.