Although subacute granulomatous thyroiditis(SGT) is usually diagnosed clinically, papillary carcinoma or other thyroid conditions must be considered in the differential diagnosis.
We retrospectively reviewed the clinical and fine-needle aspiration(FNA) cytologic findings seen in 10 SGT cases to decide what are the most reliable cytologic findings and the most helpful molecular tools for reaching a confident cytologic diagnosis. The most representative smear slides were retrieved to perform immunocytochemistry for cytokeratin19(CK19) and Ret protein. Five papillary carcinomas(PTCs) were included as controls. The constant and typical cytologic findings of SGT were multinucleated giant cells(MGCs) (100%), epithelioid granulomas(90%), an inflammatory dirty background(90%) and plump transformed follicular cells(80%) without fire-flare cells, oncocytic cells or transformed lymphocytes. The immunoreactivities for CK19(37.5%) and Ret(10%) of the follicular cells of SGT were less than those(CK19 and Ret:100%) of PTC. CK19 immunoreactivity of the MGCs was seen in only one case of PTC. There was no significant difference between CK19 and Ret immunocytochemical staining for the MGCs of both SGT and PTC. The results of this study demonstrate that the cytological diagnosis of SGT can be improved by employing a combination of the typical and constant diagnostic cytological features and immunocytochemical results.
To evaluate the morphogenesis of the human thyroid, a histologic study was made based on 100 normal thyroids of human embryos and fetuses ranging in age from 4 to 42 weeks of gestation. The embryos were serially sectioned and fetuses were examinated as an individual organ. 1) The first sign of thyroid primordium was the spherical proliferation of median ventral pharyngeal wall at the 4th week of development. 2) At the 6th week of gestation, the thyroid differentiated into two lobes that were connected by an isthmus, and was on the way of migration to the definite position from the foramen cecum. 3) The developing thyroid consisted of two cell cords, solid nests or interconnecting complex pattern until 14th week of gestation, when the entire portion of thyroid was replaced by follicles of variable size. 4) At the 9th week, the first follicle was recognizable at the periphery of the gland. 5) At the 14th week, follicles were partly filled with faintly eosinophilic colloid. 6) After the 18th week of gestation, lobulation of the thyroid parenchyme was a prominent feature. 7) After the 24th week, large follicles with rich colloid content are distributed through both superificial and deep portions. And after the 34th week, maturation reached the general pattern of adult thyroid. 8) The ability of thyroglobulin synthesis which was confirmed by PAP method, was first recognized at the 10th week of gestation.