Psammoma bodies (PBs) form an important diagnostic criterion of papillary thyroid carcinoma (PTC), but their mechanism of formation is not clear. Following our observation in a case of PTC that laminated hyaline globules may be the precursor form of PBs, the present study was undertaken to find out their relation to PBs in PTC cases. Fifty-four cases of PTC and 14 follicular neoplasms, diagnosed by fine-needle aspiration (FNA) cytology, were studied by one of the investigators (DKD) to find out the PBs, irregular calcifications, hyaline globules, and other forms made of similar material. PBs along with irregular calcification were present in five PTC cases, PB alone was present in 1 case, and irregular calcification alone was present in 4 cases. Large hyaline globules (LHGs), small hyaline globules (SHGs), branching hyaline cylinders (BHCs), and irregular hyaline deposits (IHDs) were identified in 10, 14, 6, and 9 cases, respectively. One or more of these four forms were present altogether in 18 (33.3%) of PTC cases and none of the follicular neoplasms (P=0.0142). These forms were present in 80.0% of cases with PB/irregular calcifications as opposed to 22.7% in cases without them (P=0.0012). Our observations suggest that LHGs, SHGs, and BHCs are precursors of PBs and IHDs serve as a nidus for irregular calcification.

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Although fine-needle aspiration (FNA) cytologic features of conventional papillary thyroid carcinoma (PTC) and some of its variants have been documented in the literature, PTC with an adenoid cystic pattern has not so far been described. A 35-year-old woman presented with solitary cold nodule in the right lobe of thyroid. FNA smears from the nodule showed features of PTC such as papilliform clusters, monolayered sheets, psammoma bodies, increased frequency of nuclear grooves, and intranuclear cytoplasmic inclusions. In addition, there were areas of follicular formation and light-pink to deep-purple hyaline globules with a laminated appearance and surrounded by neoplastic cells, reminiscent of adenoid cystic carcinoma. These globules were present in 53% of the follicles. Immunocytochemical staining for thyroglobulin yielded positive cytoplasmic reaction in the neoplastic cells. Histopathology of the thyroidectomy specimen confirmed the cytodiagnosis of PTC. The hyaline globules were present focally and were light pink to deep purple with a laminated appearance resembling psamomma bodies. The colloid and follicular cells were positive for thyroglobulin but the hyaline globules were negative. Von Kossa staining for calcium revealed positive reaction in the psamomma bodies and some of the hyaline globules, indicating that the globules may be the beginning of psammoma bodies. Thus, FNA cytology was useful in diagnosing an unusual variant of PTC.