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Immunohistological Study of Nonfunctional Parathyroid Carcinoma

The histological and immunohistological features of a nonfunctional parathyroid carcinoma obtained from a 56 year old woman are reported. Macroscopically, the tumor consisted of many small hemorrhagic nodules and showed adhesion to the thyroid gland and esophageal wall. Histologically, the tumor cells resembled parathyroid chief cells, and showed an island like or sheet‐like arrangement, the former showing cystic degeneration and containing hemorrhagic fluid in the extracellular space. Tumor cells resembling water‐clear cells and oxyphilic cells were also observed. Most of the the tumor cells had glycogen in the cytoplasm. Immunohistologically, the tumor cells showed no staining with anti‐thyrogiobulin, JT‐95 or anti‐cal‐citonin antibodies. However, they were stained with antibodies against chromogranin A (Ch A) and the N terminal portion of human parathyroid hormone (PTH (N)). The positive staining with anti‐PTH (N) antibody disappeared when the antibody was absorbed with excess synthesized human PTH (N). Immunostaining for PTH (N) and Ch A was useful for differentiation of nonfuctional parathyroid carcinoma from thyroid carcinoma and thymoma. Acta Pathol Jpn 42: 279‐285, 1992.