Microvessel density in human normal and neoplastic parathyroids.

Objective. Information on angiogenesis in parathyroid pathology is scanty and in particular no data are available in parathyroid carcinomas. The aim of this study was to analyze angiogenesis as microvascular density (MVD) in parathyroid neoplastic progression from normal gland to adenoma and carcinoma. Methods. Sections from formalin-fixed, paraffin-embedded specimens of 33 normal parathyroids, 43 sporadic parathyroid adenomas, and 6 parathyroid carcinomas were cut for immunohistochemistry using anti-endothelial marker CD34. MVD was evaluated in each specimen as number microvessels per mm2. MVD data were compared with some anatomoclinical parameters as tumor size, serum calcium, and parathyroid hormone (PTH) level. Results. All normal parathyroid glands, all carcinomas, and 8 adenomas out of 43 (18%) showed MVD less than 100 microvessels/mm2 (median 70.8; 95%CI 66.9-88.5); in the majority of parathyroid adenomas (n = 35; 82%) the number of microvessels/mm2 was higher than 100 (median 188.3; 95%CI 174.9-210.1). In adenomas both preoperative serum intact PTH concentration and the diameters were significantly and inversely related to the microvessel density (r = 0.320, p < 0.05 and r = 0.334, p < 0.05, respectively). Conclusions. This study shows that in parathyroid adenomas MVD is heterogeneous and negatively related to the endocrine activity (secretory status and tumor size). Therefore, angiogenesis in parathyroid adenomas and carcinomas appears to be an early event, which does not follow a parallel increase in size.