Their relatively small size and intrathyroidal localization likely account for the belated recognition of the parathyroid glands and the even later identification of their physiological functions. The parathyroid glands were the last organ to be recognized in man, and were discovered in 1855 by Owen in England and in 1880 by Sandström in Sweden. The normal four parathyroid glands are derived from the pharyngeal pouches, the upper glands from the fourth pouch and the lower glands from the third pouch. Normally 80-97% of adults have four glands, but 5% have fewer than four, and 3-13% have supernumerary glands. Each gland usually measures 3-7 mm and weights 30-40 mg each, with the largest normal gland not exceeding 70 mg. There are two parenchymal cell types: the predominant chief cells that have organelles similar to those found in other endocrine tissues, and the oxyphil cells, that ultrastructurally are characterized by the presence of closely packed mitochondria. A comprehensive understanding of the microscopical anatomy and embryology of the parathyroid glands is a requisite to the successful clinical and surgical management of parathyroid disease conditions.
Background: Breast cancer is one of the most common malignant forms of neoplasia worldwide; programmed death protein 1 (PD-1), an inhibitory receptor of T lymphocytes, and its ligand programmed death ligand 1 (PD-L1), play an important role in the ability of tumor cells to evade the host's immune system.
Methods:We conducted a descriptive, observational study using retrospective data and an open evaluation using immunohistochemistry to determine the general prevalence of PD-L1 expression in 63 women with breast cancer who underwent a modified radical mastectomy, or quadrantectomy, with axillary lymph node removal.
Results:The prevalence of PD-L1 expression was 32% in patients with breast cancer treated with radical mastectomy. PD-L1 expression was higher in patients with large tumor size (19% for pT1, 37% for pT2, 50% for pT3, and 100% for pT4), metastasis in regional lymph nodes (25% for N0, 38% for N1, 75% for pN2, and 38% for pN3), and higher histological grade carcinoma (0% for grade 1, 23% for grade 2, and 50% for grade 3).Conclusions: These findings suggest that PD-L1 expression is heterogeneous in breast cancer tumors and that its expression varies highly in tumor regions over time. The evaluation of PD-L1 expression is significant, because of the therapeutical implications that could improve the outcomes and prognosis of these patients.
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