Gia-Khanh Nguyen

Hashimoto's thyroiditis: Cytodiagnostic accuracy and pitfalls

To determine the cytodiagnostic accuracy rate and pitfalls of Hashimotos thyroiditis (HT), the files and smears prepared from the thyroid needle aspirates of 146 patients with suspected HT and/or clinically and serologically confirmed HT were reviewed. Of those patients, 105 presented with a diffuse and rubbery thyroid enlargement, and 41 with one or two prominent nodules. For the first group (105 patients), the needle aspiration biopsy (NAB) was performed on one or two thyroid lobes during their initial endocrinologic consultation, and for the second group (41 patients), the NAB was performed on and around the predominant nodules that were found either at initial physical examination or during the patients routine follow‐ups. In 134 cases, a cytodiagnosis of HT was made on the first NAB. Among the 41 patients with a prominent thyroid nodule, a thyroid neoplasm was suspected clinically in four because their thyroid nodules increased in size. In the other 12 patients, a cytodiagnosis of follicular neoplasm (FN) was made in five cases, and a Hürthle cell tumor (HCT) was diagnosed or suspected in seven patients. All 16 patients had thyroid surgery, and a HT was histologically confirmed in all cases. In the first four patients, no tumor was found. Among five patients with a cytodiagnosis of FN, one had a hyperplastic follicular cell nodule (HFCN), two had follicular adenomas, and two had papillary carcinomas of follicular variant. For the seven patients with a cytodiagnosis of HCT, HCT was confirmed in three, three were found to have hyperplastic Hürthle cell nodules (HHCN), and one showed a benign colloid nodule with Hürthle cell changes and remote hemorrhagic necrosis. It is concluded that NAB is highly sensitive in diagnosing HT, with a diagnostic accuracy rate of 92% by the first biopsy attempt. The cytologic differential diagnosis between an HFCN and a follicular neoplasm and between an HHCN and an HCT is impossible in some cases. Diagn. Cytopathol. 16:531–536, 1997.

Cytodiagnosis of benign and malignant hürthle cell lesions of the thyroid by fine-needle aspiration biopsy

Eighty‐two Hürthle cell (HC) lesions of the thyroid with cytologic evaluation by fine‐needle aspiration biopsy (FNAB) were reviewed. In 17 cases the FNAB was not diagnostic because the fine‐needle aspirates (FNAs) were too scanty in cellularity. Among the remaining 65 lesions, there were 45 HC adenomas (HCAs), six non‐neoplastic HC nodules (NHCNs), 10 primary HC carcinomas (HCCs), and four metastatic HCCs. Forty‐four HCAs were diagnosed as HC tumor (HCT), and one HCA was wrongly diagnosed as medullary carcinoma. All six NHCNs were wrongly diagnosed as HCT. Of 10 primary HCCs, three were diagnosed as HCT and seven as suspected HCC. Four metastatic HCCs were correctly diagnosed. The FNAs from 38 HCAs and four NHCNs were predominantly composed of large monomorphic HCs with oval nuclei, inconspicuous nucleoli, and abundant, well‐defined, granular cytoplasm present singly, in acinar arrangement, and in monolayered sheets of variable sizes. Nuclear pleomorphism and prominent nucleoli were noted in seven HCAs and two NHCNs. Occasional small syncytial tumor cell clusters (STCCs) were noted in six cases, and a few naked tumor cell nuclei (NTCN) were observed in 16 cases. The FNAs from 14 HCCs were hypercellular. In all cases tumor cells were relatively small and showed monomorphic or pleomorphic nuclei, prominent nucleoli, and ill‐defined cytoplasm. STCCs of variable sizes were present in abundance in 10 cases, and numerous NTCN were noted in 12 cases. In two HCCs, the tumor cells with well‐defined cytoplasm were present singly and in cohesive sheets, and no STCCs or NTCN were observed. Thus, the presence of small tumor cells with ill‐defined cytoplasm and prominent nucleoli in syncytial clusters and abundant NTCN in the FNA of a thyroid nodule should alert the observer about the strong possibility of an HCC. Diagn. Cytopathol. 1999;20:261–265.u2003

Fine-needle aspiration biopsy cytology of hyalinizing trabecular adenomas of the thyroid

Cytologic smears from fine‐needle aspirates of three histologically and ultrastructurally confirmed hyalinizing trabecular adenomas of the thyroid (HTAT) were reviewed. In two cases a cytodiagnosis of HTAT was suggested, and in one patient a diagnosis of trabecular epithelial neoplasm was made. In all three cases, small clusters and sheets of epithelial cells with abundant, filamentous, vacuolated, and ill‐defined cytoplasm were present. The nuclei were slightly pleomorphic and showed nuclear overlapping, nuclear grooves, and intranuclear cytoplasmic inclusions. Small and irregular fragments of acellular hyalinized material (AHM) were noted within the tumor cell clusters in the first two cases. In the third patient, large syncytial sheets and anastomotic cords of epithelial cells showing ill‐defined, filamentous cytoplasm, slightly pleomorphic nuclei, nuclear overlapping, intranuclear cytoplasmic inclusions, and nuclear grooves were present. Fragments of AHM were not observed within clusters and syncytial sheets of tumor cells. Diagn. Cytopathol. 1999;20:90–94.

Cytopathology of malignant mesothelioma of the pleura in fine-needle aspiration biopsy.

The cytologic findings in fine‐needle aspiration biopsy (FNAB) of 9 histologically, immunohistochemically, and ultrastructurally confirmed malignant mesotheliomas of the pleura were reviewed. There were 4 epithelial malignant mesotheliomas (EMM), 3 sarcomatous mesotheliomas (SM), 1 mixed malignant mesothelioma (MMM), and 1 poorly differentiated malignant mesothelioma (PDMM). In FNAB, three EMMs yielded polygonal malignant cells with oval nuclei and prominent nucleoli, singly, in small sheets, and in tridimensional clusters with smooth or lobulated contours. In one EMM, only atypical mesothelial cells with prominent nucleoli were seen singly and in loose aggregates. In FNAB, two SM showed malignant spindle‐shaped cells (MSC) with scant, ill‐defined cytoplasm singly and in loose clusters. Cohesive clusters of elongated and polygonal cells with ill‐defined, clear cytoplasm and pleomorphic nuclei containing small or prominent nucleoli were observed in one SM, with extensive clear‐cell changes. In needle aspirates, the MMM showed polygonal malignant cells in clusters admixed with MSC. The PDMM displayed single and clustered large pleomorphic malignant cells, with prominent single or multiple nucleoli. Electron microscopic examination of minute tissue fragments retrieved from the FNAB in 2 cases of EMM revealed epithelial mesothelial cells with well‐formed desmosomes and long slender microvilli (LSM) on the free tumor cell surfaces. In one case, LSM in direct contact with collagen fiber bundles in the tumor tissue matrix were observed, supporting the diagnosis of an invasive EMM. Diagn. Cytopathol. 1999;21:253–259.