microscopically 1. Regressive changes: fibrosis, hemorrhage, calcification, cystic 2. Colloid-rich follicles lined by flattened epithelium and areas of follicular epithelial hypertrophy and hyperplasiamicroscopically 1. Regressive changes: fibrosis, hemorrhage, calcification, cystic 2. Colloid-rich follicles lined by flattened epithelium and areas of follicular epithelial hypertrophy and hyperplasia;