Fine-needle aspiration of a follicular dendritic-cell tumor: report of a case and review of the literature.

Follicular dendritic-cell tumors (FDCT) are rare neoplasms, well-characterized in surgical pathology material. There are, however, few cytopathology reports. We describe the fine-needle aspiration (FNA) findings of a histologically confirmed FDCT. Conventional smears and a cell block showed large spindle to oval neoplastic cells admixed with small mature lymphocytes. The neoplastic cells were present mainly in small syncytial clusters. Immunostains for CD21 and CD35, performed on the cell block, were positive in the neoplastic cells. The diagnosis was fully confirmed by the presence of typical immunohistochemical and ultrastructural features on the surgically removed tumor. The differential diagnosis of FDCT is broad and includes other tumors characterized by an admixture of large neoplastic cells and small mature lymphocytes, such as thymomas, lymphoepithelioma-like carcinomas, and interdigitating dendritic-cell tumors. It may not be possible to diagnose FDCT based on FNA material without the use of immunocytochemical and electron microscopic studies. Certain cytomorphological characteristics, however, might suggest its diagnosis and allow the practicing cytopathologist to perform confirmatory studies.

ThinPrep vs. conventional smears in fine-needle aspirations of sarcomas: A morphological and immunocytochemical study.

Very limited data exist describing the characteristics of sarcomas sampled by fine-needle aspiration (FNA) and processed by the ThinPrep (TP) method. We compared the cytopathological and immunocytochemical features of sarcoma aspirates prepared using both the conventional and TP method. We reviewed 70 sarcoma FNAs. Samples were first used to prepare conventional smears and the remainder of the specimen was rinsed in Cytolyt. The average number of slides examined per case was two for the TP method and five for the conventional technique. Immunocytochemistry for different markers was performed in a subset of cases. Sixty-five cases were positive for sarcoma both by conventional and TP methods. Five cases were positive by one method only. Cellularity was higher on conventional slides. In terms of cytoarchitecture, TP slides revealed fewer thick clusters, more single cells that were more evenly distributed, and sometimes distortion of expected cellular arrangements and architectural patterns. Cytomorphological and nuclear details were better preserved on TP slides. The background of TP slides revealed a reduction of blood but also some loss of necrosis and characteristic background tumor features. Immunocytochemical staining revealed superior results on TP slides. TP and conventional slides showed good correlation. TPs were excellent for immunocytochemistry and represent an alternative to conventional smears when expertise in slide preparation is not available. However, TPs may require additional experience in the interpretation of sarcomas, mainly related to the loss of tumor-specific background features. They are useful as an adjuvant to conventional smears in sarcoma diagnoses, particularly when special studies are needed. Diagn. Cytopathol. 1999;21:351-354.

Cytopathology of insular carcinoma of the thyroid.

BACKGROUND: Insular carcinoma of the thyroid (ICT) first was reported in 1984. To the authors' knowledge, few cytology reports have been published since that time. The authors describe the cytologic features of six tissue-proven ICTs and propose criteria that suggest its diagnosis. METHODS: Four cases were thyroid fine-needle aspiration (FNA) samples. Two cases were FNAs of metastases. All cases were found to be classic ICT on examination of primary or metastatic surgical specimens. RESULTS: Three cases originally were diagnosed as carcinoma, including two FNAs of metastatic sites and one thyroid FNA. Two additional thyroid FNAs were diagnosed as suspicious for malignancy, favor follicular neoplasm. One case was termed a neoplasm, favor follicular type. Smears showed high cellularity and scanty colloid. Three cases were found to contain some microfollicles. One case showed a few papillae. Necrosis and mitosis were rare. Cells were round with pale, poorly defined cytoplasm. Nuclei were round and monomorphic with finely granular chromatin, mild hyperchromasia, smooth nuclear membranes, and small nucleoli. Nuclear grooves and inclusions were rare. CONCLUSIONS: Three cases were diagnosed as suspicious for follicular neoplasm, the main differential diagnosis of ICT. Both tumors exhibited high cellularity and scanty colloid. However, ICT showed a predominance of single cells whereas follicular neoplasms reveal microfollicles with more nuclear atypia. There is cytologic overlap between these two neoplasms. Papillary thyroid carcinoma should be distinguished from ICT easily because the latter usually does not reveal the classic cytologic features associated with the former. ICT should be considered in the differential diagnosis of follicular neoplasms. Features favoring ICT are predominance of single cells, small loose nests of cells with few microfollicles, and little nuclear atypia. Cancer (Cancer Cytopathol)

The cytology of extraskeletal Ewing sarcoma.

BACKGROUND: Extraskeletal Ewing sarcoma (EES) shares histologic, immunohistochemical, and molecular findings with ES of bone. The authors' goal in conducting this study was to examine the cytomorphologic features of EES. In addition, immunocytostaining for CD99/O13 was performed in all cases, and cytogenetic and molecular data were available in about half of the cases. METHODS: The authors studied 20 aspiration cases, all with histopathologic confirmation, and also conducted immunohistochemistry and/or molecular studies. RESULTS: All cases had cellular smears with many single cells and focal clustering. Numerous naked nuclei and focal crush artifacts were seen. Mitosis and necrosis were rare. Four cases had cytoplasmic vacuoles. Five cases showed nuclear molding. Seventeen cases (85%) exhibited small cells with scanty cytoplasm and nuclei with fine chromatin and small nucleoli, representing the so-called typical variant. One case (5%) revealed cells with abundant cytoplasm, large nuclei, and large eosinophilic nucleoli, an example of the atypical or large cell variant. Two cases (10%) had features in between, with cells showing a fair amount of cytoplasm and medium-sized nucleoli, representing the intermediate variant. Nuclear grooves, described as common in the latter, were rare. In all cases, in either cytologic or corresponding histologic material, CD99/O13 immunocytostaining showed strong membranous reactivity. In addition, cytogenetic and/or molecular evidence of ES specific chromosomal translocation was demonstrated in histologic or cytologic material in 10 cases. CONCLUSIONS: EES shows cytologic features similar to ES of bone, with a spectrum of changes ranging from the typical appearance in a majority of cases to intermediate and atypical variants in a minority of cases. CD99/O13 immunocytostaining and/or molecular studies, particularly in the intermediate and atypical variants, may help in establishing a definitive fine-needle aspiration diagnosis, thus avoiding an open surgical biopsy.

Multinucleate giant cells in papillary thyroid carcinoma. A morphologic and immunohistochemical study.

Multinucleate giant cells (MGCs) occur in a variety of inflammatory, hyperplastic, and neoplastic thyroid disorders. They also have been recognized as a feature of papillary thyroid carcinoma (PTC), particularly in fine-needle aspiration biopsies (FNAB). However, the origin of the MGCs and their comparative frequencies in histologic and cytologic preparations have not been established. Therefore, histologic sections from 76 cases of PTC were examined and immunohistochemical analyses for epithelial and histiocytic markers were performed. Giant cells were identified in histologic sections of 35 cases (46%) of PTC. In cytologic preparations, MGCs were identified in 12 of 22 cases (55%). MGCs were present within follicles or adjacent to papillae, and were often associated with resorption of colloid. Immunohistochemical results indicated that MGCs were of histiocytic rather than epithelial origin. Multinucleate giant cells in PTC most likely represent a response to leakage of colloid into the interstitium. Although MGCs have been described most commonly in inflammatory conditions of the thyroid, the results of this study suggest that their presence should prompt a careful appraisal of associated PTC.