The role of respiratory cytology is to detect and classify pulmonary disease, with an emphasis of neoplastic disease, so that proper therapy can be instituted. As in many branches of cytology, the recognition of malignancy in the cells obtained from the respiratory tract is more straightforward than identifying the type of tumor cell. It is important to accurately determine the true cytopathological cell type in cases of primary lung cancer and to know the accuracy of the diagnosis achieved by the cytological procedures. The well differentiated tumors have characteristic cytoplasmic and nuclear abnormalities that enable physicians to firmly categorize these lesions, as in squamous cell or adenocarcinoma, but some moderately and most poorly differentiated tumors show few distinctive features. This article reviews the malignant and reactive pulmonary cytologic findings and we also report on some of their pitfalls and the cytologic criteria.

The major categories of neuroendocrine tumors of lung are typical carcinoid, atypical carcinoid, large cell neuroendocrine carcinoma, and small cell carcinoma. The histologic classification criteria of neuroendocrine tumors are well documented in the "WHO Classification of Tumors" based on mitotic figures and necrosis. Cytologic characteristics of neuroendocrine tumors are trabecular, acinar, and solid arrangement of tumor cells and occasional rosette formation. Nuclear chromatin patterns are characteristically described as "salt and pepper chromatin pattern". Many of cytologic classifications documented in the literature are before the "WHO Classification". In this review, the cytologic features of pulmonary neuroendocrine tumors are documented according to the WHO classification, and recent concepts of neuroendocrine tumors of lung are discussed.

The lungs are one of the most common visceral sites for metastatic disease. The identification of a metastasis from a second primary lung tumor is clinically important for patients with pulmonary metastases of an extrathoracic origin. Although the cytologic features of metastatic tumors involving the lung have been extensively described, making the cytologic diagnosis is usually not easy in the absence of clinical information. However, the immunohistochemical staining for many tumor markers and the different expressions of cytokeratin 7 and 20 are very useful in the diagnosis. This review presents the cytomorphological spectrum of metastatic tumors along with the immunohistochemical findings.

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 cytokeratin 19(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.

Fine needle aspiration (FNA) cytology of the breast is a useful method for diagnosing breast lesions. Yet making the definite diagnosis with performing FNA is limited by some problems, such as the low cellularity, the poor preservation and the obscuring background. Recent studies have found that liquid-based cytology solves such problems, but it is an expensive method and it is limited by the loss of the background information. The purpose of this study is to compare the Liqui-$PREP^{TM}$, a new manual liquid-based method of cytology, and the conventional smears for analyzing breast FNA cytology materials. A total of 31 randomized FNA specimens of breast were studied. In each case, both the conventional smears and the Liqui-$PREP^{TM}$ method were performed, and the smears were evaluated for cellularity, cellular preservation, the background, the cytologic features and the architectural arrangement. The cellularity and architectural arrangement were equal for both preparations. The Liqui-$PREP^{TM}$ specimens showed better cellular preservation, loss of the obscuring background, no overlapping of cells and a smaller area to screen compared with the conventional smears. Moreover, it has the potential advantages of being able to use the remaining specimens for immunohistochemical study and ploidy analysis, and it can reduce the costs for preparation compared with the other liquid-based methods of cytology. But some background information is lost in the Liqui-$PREP^{TM}$ specimens, the same as the other liquid-based methods of cytology. In conclusion, the Liqui-$PREP^{TM}$ and conventional smears showed good correlation, but they have their respective advantages and disadvantages. These results suggest that Liqui-$PREP^{TM}$ can contribute to making the accurate diagnosis with performing breast FNA cytology when it is used along with other methods.

In an attempt to better define the cytologic characteristics of schwannomas, we have reviewed aspirates and corresponding histologic sections from 23 schwannomas. Of this number, the original cytologic diagnoses were: schwannoma in 14 cases (61%), benign soft tissue tumor in 2 cases (9%), and insufficient specimen in 7 cases (30%). The cytologic findings common to all cases of schwannoma included fragments of tightly cohesive fascicles with variable cellularity and corresponding Antoni type A area. The Antoni type B area, consisting of scattered spindle cells and some histiocytes and lymphocytes against a myxoid background, was seen in 14 cases. Fibrillary stroma was seen in 12 cases. The tumor cells had spindle- or ovalshaped nuclei, with pointed ends and indistinct cell borders. Nuclear palisading was seen in 10 cases, and distinctive Verocay bodies were seen in 5 cases. In ancient schwannomas, there were no Verocay bodies. Most schwannomas have distinct cytomorphologic features that allow correct diagnosis. The major problem with fine needle aspiration cytology of these tumors is the high frequency of poor cellularity, particularly in lesions with cystic degeneration. Of 7 cases with insufficient specimen, 4 showed marked cystic changes and 1 showed marked hyaline changes on histologic sections. In conclusion, we believe that if cytopathologist reminds the situation such as cystic degeneration or hyaline degeneration, the correct diagnosis of the schwannoma will be easily made.

Adenomatoid tumor is a benign neoplasm of a mesothelial origin, and it usually occurs in the reproductive organs, especially in the epididymis. The author experienced a case of adenomatoid tumor involving the tunica albuginea and testicular parenchyme without any evidence of epididymis involvement. The patient was a 36-year-old man with a painless scrotal mass that he had experienced for 2 months, and this mimicked testicular neoplasia, including metastatic carcinoma, or other benign lesions. The imprint cytology of the tumor showed a hypocellular smear with mainly arranged cells in cohesive monolayered clusters along with occasional singly dispersed cells and naked nuclei in a clean background. The cellular clusters formed vague glandular and cord-like structures. The tumor cells were large polygonal to columnar cells with a relatively monomorphic appearance. The nuclei were oval to round shape and they showed vesicular, fine chromatin and inconspicuous nucleoli. The cytoplasm was moderate to abundant, and it contained fine vacuoles in some tumor cells. Mitoses and cellular pleomorphism were not present. Awareness of the cytologic finding of this lesion is necessary to screen or differentiate a testicular or paratesticular mass before and/or during surgery because the cytology may be useful as a diagnostic tool. Pathologists should be aware of the cytologic features of common lesions in this anatomic region so as to avoid performing aggressive and unnecessary surgical procedures.

Epithelial-myoepithelial carcinoma (EMC) is a low grade malignant neoplasm that commonly occurs in the parotid gland. Recently, we investigated a case of EMC that occurred in the external auditory canal (EAC) in a 35-year-old male, and this tumor was initially diagnosed as pleomorphic adenoma. The difficulty associated with diagnosing EMC by aspiration cytology arises from both the rare incidence of this tumor and the overlapping spectrum of cytological features found in various salivary gland tumors, such as pleomorphic adenoma, basal cell adenoma and adenoid cystic carcinoma.

Giant cell tumor of the tendon sheath (GCTTS) is a slowly growing, benign soft tissue tumor. The tumors occur predominantly on the hands and feet. Although the clinical and histopathologic features are well-defined, only a few reports have described the cytologic appearance of this entity. A 26-year-old woman presented with a gradually developing circumscribed soft tissue mass near the proximal phalanx of her left little finger for one year. Imprint and fine needle aspiration (FNA) smears were obtained from the excisional biopsy specimen. The imprint smears were composed of predominantly singly dispersed bland mononuclear cells and several giant cells. The mononuclear cells were polygonal to round, and they showed a histiocyte-like appearance. Osteoclast-type multinucleated giant cells of various sizes were randomly scattered throughout the smears, and these cells contained 3 to 50 nuclei. Nuclear atypia and pleomorphism were absent in both the single and giant cells. Loose aggregates of hemosiderin-laden macrophages and binuclear stromal cells were also seen. The cytologic features of the FNA smears were similar with those of the imprint, Additionally, the FNA smears contained several clumps of densely collagenous stromal tissue that were seldom noted in previously reported cytologic material. The cytologic features were well-correlated with the concurrent histologic findings and the diagnosis of GCTTS was made. When the clinical and radiologic datas are integrated, the diagnosis of GCTTS can be strongly suggested, based on the pre-operative cytologic specimen.