Confocal laser scanning microscopic observation of angioarchitectures in human thyroid neoplasms.

Confocal laser scanning microscopy (CLSM) was employed to study the blood vascular system of human thyroid tumors. CLSM observation combined with immunohistochemistry for type IV collagen clearly visualized 3-dimensional images of the microvascular structures. CLSM observation showed that normal thyroid follicles were tightly covered by branching microvessels, whereas microvessels in follicular adenomas were more prominent and more irregular in shape. Microfollicular adenomas showed that neoplastic small follicles were attached to the capillaries and had a "grape-like" appearance. Strikingly well-developed vascular networks were seen in neoplastic follicles of papillary carcinomas. Interestingly, papillae of papillary carcinoma occasionally contained contained aggregated vascular complexes (glomeruloid structure) composed of tortuous, densely packed, and irregularly arranged small vessels. Such aggregated vascular complexes were seen in 5 of 7 papillary carcinoma tissues but not in other histological thyroid tumors. Our findings indicate that the fundamental vascular pattern correlates well with the growth pattern, suggesting an interdependence between parenchyma and stroma characteristic for thyroid tumors. CLSM observation combined with immunohistochemistry may contribute to a better understanding of morphological characteristics of angioarchitecture in human surgical materials.