Parathyroid carcinoma is a rare disorder accounting for 0.5% to 5% of parathyroid neoplasia. Diagnosis of parathyroid carcinoma in fine needle aspiration cytology (FNAC) is difficult because ail characteristic features of parathyroid carcinoma can be recognized in parathyroid adenoma or hyperplasia. Cellular atypism cannot be used for the diagnostic criteria of parathyroid carcinoma as malignancies of most other organs. We experienced two cases of cytologic features of parathyroid carcinoma confirmed by histologic examination. The majority of tumor cells formed large cohesive clusters, although individual tumor cells were also present. The tumor cells displayed rather pleomorphic round to oval nuclei, occasional prominent nucleoli, and distinct cytoplasmic margin. Occasionally karyolysis, anuclear cells, and nonepithelial cell clusters were noted. The histologic findings showed a partially lobulated architecture, with admixture of sheets of chief cells, oxyphil cells, and occasional water clear cells. The tumor infiltrated into the thyroid parenchyme and perithyroidal soft tissue. The electron microscopic study of case 1 disclosed typical findings of parathyroid neoplasm; clusters of secretory chief cells with centrally located round to ovoid nuclei, moderately clumped heterochromatins and one or two nucleoli. The tumor cells showed conspicous interdigitation of contiguous ceil membrane and intercellular microvilli.

Hyalinizing trabecular adenoma of the thyroid gland is a rare benign neoplasm predominantly diagnosed in middle-aged women. Carney et al. first described this entity that may mimic paraganglioma, medullary carcinoma and papillary carcinoma in 1987. We describe cytologic and histopathologic features of a case of hyalinizing trabecular adenoma combined with occult papillary carcinoma in the opposite lobe. A 55-year-old woman presented with nontender palpable mass of the right neck for 6 months. The aspirate was cellular and contained small clusters and sheets of epithelial cells with abundant filamentous, vacuolated, and ill-defined cytoplasm. The nuclei were slightly pleomorphic and showed nuclear overlapping, nuclear grooves, and intranuclear cytoplasmic inclusions. Histologic examination showed hyalinizing trabecular adenoma in the right lobe and occult papillary carcinoma in the left lobe.

Ganglioneuroma is a well-differentiated, benign tumor of the sympathetic nervous system. These tumors belong to a family of neoplasm that exhibit a wide range of differentiation, with neuroblastoma at one end and ganglioneuroma at the other. Because it share morphologic features with other both benign and malignant neural tumors, accurate preoperative diagnosis is often difficult. Nonetheless, it is critical for proper management. Fine needle aspiration cytology (FNAC) in the diagnosis of the ganglioneuroma has been a little documented. We describe a case of mediastinal ganglioneuroma in a 33-month-old girl. The diagnosis was suggested on FNAC and was confirmed by histopathologic examination later.

Insular carcinoma of the thyroid(ICT) is an uncommon thyroglobulin-producing neoplasm, intermediate between well differentiated and anaplastic carcinoma. Only a few publications have addressed the fine needle aspiration cytologic(FNAC) findings from ICT. We experienced a case histologically diagnosed as ICT and with preoperative FNAC in a 52 - year - old woman. The FNAC displayed scanty colloid and abundant monomorphic follicular cells presented singly, in small loose aggregates, and in cohesive trabecular or acinar clusters. Intact insulae of tumor cells were also identified. Necrosis and mitosis were rare. Tumor cells showed round and monomorphic nuclei, finely granular chromatin, and inconspicuous nucleoli. When insular structure is identified in thyroid FNAC specimen, ICT should be included in the differential diagnosis. Herein we discuss and review the cytologic criteria for separation of ICT from other thyroid neoplasms.

Cystic hypersecretory carcinoma of the breast is a rare variant of ductal carcinoma of breast, first described in 1984 by Rosen and Scott. Histologically, it is characterized by the formation of dilated ducts and cysts containing an eosinophilic secretory product resembling thyroid colloid. Cytologic findings show a few clusters of atypical ductal epithelial cells in amorphous proteinaceous material with clacking artifact. Differential diagnosis include mucinous carcinoma and benign mucocele-like tumor. We present two cases of fine needle aspiration cytology of cystic hypersecretory intraductal carcinoma of the breast with a review of the literature.

Poorly differentiated synovial sarcoma is a variant of synovial sarcoma. We report a case of poorly differentiated synovial sarcoma imprinted after resection. The patient was a 47-year-old woman with a right shoulder pain for 6 months. The cytologic features showed malignant round to oval, monotonous tumor cells with high nuclear to cytoplasmic ratio. Some tumor cells showed perivascular distribution and nuclear melding. Vague rosette-like structures were seen. On immunohistchemical stains, tumor cells were diffusely positive for CD99 and focally positive for epithelial membrane antigen. Ultrastructural examination showed desmosomes and microvilli.

Multinucleated giant cells of osteoclast-like appearance can be seen in a type of anaplastic carcinoma of thyroid and only a few case reports for fine needle aspiration cytologic findings are found in the literatures. Recently, we experienced a case of anaplastic carcinoma of thyroid with many osteoclast-like giant cells in a 72-year-old woman. The cytologic features and immunohistochemical results are described with special emphasis on differential diagnosis.

Epithelioid hemangioendothelioma is a rare vascular tumor of borderline malignancy which is characterized by the presence of "epithelioid" or "histiocytoid" endothelial cells. Superficial and deep tumors have been recognized in the extremities, head, neck, chest, and mediastinum of adult patients. It may also occur as a primary tumor of liver, bone, and other visceral organs. Few effusion cytologic findings of epithelioid hemangioendothelioma have been reported. We report a case of composite epithelioid hemangioendothelioma with focal epithelioid angiosarcomatous areas of the iliac bone and adjacent soft tissue in a 38-year-old female, which, during its metastatic course, was presented as a pleural effusion. The effusion was cellular with epithelioid cells presenting both singly and in clusters. The tumor cells were round to ovoid shewing cytoplasmic vacuolization, variability in cell size, and prominent nucleoli. The effusion smears and cell block sections revealed strong positive staining for CD31 and vimentin, weak positive for CD34 and Factor VIII-related antigen, and negative for cytokeratin, CEA, and calretinin. The cytologic findings in this case were similar to that of metastatic adenocarcinoma or malignant mesothelioma. Therefore, immunocytochemical staining in smear and cell block is a helpful tool to differentiate malignant 'epithelioid' cells in effusion.