Decisive role of intermediate filament typing of tumor cells in the differential diagnosis of difficult fine needle aspirates

Thirty-six diagnostically difficult fine needle aspirates from enlarged lymph nodes and malignant soft tissue tumors, containing tumor cells with scanty or no obvious light microscopic features indicative of their differentiation, were assessed by a panel of six cytopathologists. Their diagnoses were recorded and then compared with the definitive diagnosis established by combining the cytologic findings with the results of intermediate filament typing of tumor cells in the smears using monoclonal antibodies specific for each filament type. The results show that use of these antibodies can markedly improve the accuracy of the cytologic diagnosis of tumor type as well as revise or prevent erroneous cytologic diagnoses in difficult cases. This pertains especially to the differential diagnoses of carcinoma versus malignant lymphoma, carcinoma versus malignant melanoma, carcinoma versus sarcoma and squamous carcinoma versus carcinoma of simple epithelia. Intermediate filament typing of tumor cells in aspirates as an objective histogenetic criterium makes the differential diagnosis of the difficult aspirates much more reliable and reproducible, provided that appropriate questions are asked, monoclonal antibodies with well-defined specificities are used and the antigenicity of the intermediate filaments in smears is preserved.     

Cytomorphologic features of Merkel cell carcinoma in fine needle aspiration biopsies. A study of two atypical cases

OBJECTIVE: To report atypical cytomorphologic features in fine needle aspiration biopsies (FNABs) from two cases of Merkel cell carcinoma (MCC), a primary neuroendocrine neoplasm of skin. STUDY DESIGN: Retrospective review of FNABs with histologic correlation from six patients with MCC and a report of findings from two whose smears showed atypical features. RESULTS: Typically the aspirates produce highly cellular smears of loosely clustered and individual, relatively monomorphic, small tumor cells with round to oval, regularly contoured nuclei. In two of our cases, the tumor cell nuclei exhibited a spectrum of pleomorphism ranging from moderately complex nuclear membranes with cleaves, indentations and protrusions in one case to large, markedly bizarre, convoluted nuclei and multinucleate tumor cells in the extreme case. Both cases were primary neoplasms, and the diagnosis was based on clinical, histologic and immunohistochemical data. Additionally, electron microscopy was performed on the tumor with bizarre nuclei and demonstrated rare, dense core neurosecretory granules and paranuclear bundles of intermediate filaments.     

Coexpression of glial fibrillary acid protein, keratin and vimentin. A unique feature useful in the diagnosis of pleomorphic adenoma of the salivary gland in fine needle aspiration biopsy smears

Positive staining for glial fibrillary acidic protein (GFAP) of tumor cells in fine needle aspirates of 11 of 12 pleomorphic adenomas of the parotid gland is reported. Tumor cells in these neoplasms also coexpressed keratin and vimentin to varying extents. Coexpression of GFAP, keratin and vimentin in tumor cells in aspirates is an unusual feature, so far demonstrated only in pleomorphic adenomas. Thus, intermediate filament typing may help to distinguish: (1) pleomorphic adenomas of the salivary glands from head and neck tumors of nonsalivary gland origin; (2) intracranial metastases of malignant mixed tumors of the salivary gland from gliomas; and (3) pleomorphic adenomas from extracranial gliomas.     

Fine needle aspiration cytology of neuroendocrine tumors of the pancreas. A cytologic, immunocytochemical and electron microscopic study.

We report the fine needle aspiration cytology findings in six cases of neuroendocrine tumor of the pancreas. Three cases were from the pancreas, two from hepatic metastases and one from a peripancreatic lymph node metastasis. The cytologic features that permitted a preoperative diagnosis of pancreatic neuroendocrine tumor were: a cellular aspirate; numerous isolated cells and irregular, loose, dyshesive cellular aggregates; minimal nuclear pleomorphism; infrequent mitoses; fine, evenly dispersed nuclear chromatin with occasional inconspicuous nucleoli; a scant-moderate amount of granular, amphophilic, well-defined cytoplasm; clustering of tumor cells around segments of capillaries; and rosette formation. The differential diagnosis includes cells derived from normal pancreatic acini, islet cell hyperplasia, acinic cell carcinoma, well-differentiated pancreatic adenocarcinoma, metastatic small cell undifferentiated carcinoma of the lung, pancreatic small cell anaplastic carcinoma and malignant lymphoma. The application of immunocytochemistry to cytologic smears can be easily and reliably performed to confirm the neuroendocrine nature of the tumor and identify the specific type of polypeptide hormone or hormones produced by these tumors. Four aspirates showed immunoreactivity for chromogranin, and one was positive for gastrin. Cells of a lipid-rich neuroendocrine tumor were negative for chromogranin; however, the tissue section contained neuron specific enolase, and neurosecretory granules were demonstrated by electron microscopy.     

Fine needle aspiration cytology of mucoepidermoid carcinoma. A diagnostic problem

The cytomorphologic findings in fine needle aspirates from 18 cases of histologically confirmed primary mucoepidermoid carcinoma of the salivary gland were reviewed and correlated with the findings on the tissue sections. An accurate diagnosis of these tumors in fine needle aspirates was possible when all three components (i.e., epidermoid cells, intermediate cells and mucus-producing cells) were identified. The pitfalls in the cytologic diagnosis of this tumor are discussed.     

Endothelial cells help in the diagnosis of primary versus metastatic carcinoma of the liver in fine needle aspirates. An immunofluorescence study with vimentin and endothelial cell-specific antibodies

Fine needle aspirates of 5 primary hepatocellular carcinomas and 24 carcinomas metastatic to the liver were studied using vimentin and endothelial cell-specific monoclonal antibodies. Numerous endothelial cells dispersed and in bundles overlying clumps of tumor cells were positively stained by both antibodies in smears of primary hepatocellular carcinomas while such cells were rare or absent in metastatic carcinomas, with the exception of clear cell carcinoma of the kidney. It is concluded that endothelial cells, if present in large numbers in fine needle aspirates of a hepatic carcinoma and arranged in bundles that envelope the clumps of tumor cells, can (1) suggest the presence of a primary hepatocarcinoma and (2) narrow the differential diagnosis with the most common metastatic cancers to renal cell carcinoma.     

Intermediate filament typing of tumor cells in fine needle aspirates by means of monoclonal antibodies

Well-characterized monoclonal antibodies directed against different intermediate filament proteins were used in the typing of tumor cells in 30 fine needle aspiration (FNA) biopsy specimens received for routine cytologic examination to assess the value of intermediate filament typing in FNA cytology. Tumors from sites that included liver, large bowel, pancreas, breast, skin, thyroid, thigh and kidney were examined with monoclonal antibodies specific for either all keratins or keratin subsets, vimentin, desmin or specific neurofilament polypeptides. Intermediate filament typing helped to confirm, revise or refine the diagnoses made by light microscopy and provided information of value in the classification of tumors of uncertain origin.     

Hemangioendothelioma. Cytologic appearances in two cases presenting with multiple soft tissue and bone lesions

Two cases of hemangioendothelioma were detected by fine needle aspiration cytology in two women presenting with multiple soft tissue and bone lesions. The aspirates were hemorrhagic, and the smears showed mostly dissociated and predominantly monomorphic tumor cells. Focal rosettelike clustering of tumor cells was also present. A prominent cytologic feature of these two cases of hemangioendothelioma was the close association of tumor cells with endothelium-lined vascular structures, a pattern that can be seen in other sarcomas and sometimes in malignant epithelial tumors.     

Chondroblastoma in fine needle aspirates.

The cytologic features of smears of fine needle aspirates from four chondroblastomas were studied. In an ideal fine needle aspiration biopsy sample of chondroblastoma, all the diagnostic details can be found: chondroid matrix surrounding individual round to oval mononuclear cells, calcifications among cells and multinucleate osteoclasts. Chondroid matrix, which we believe to be the decisive feature, and calcifications are seen better in Giemsa-than in Papanicolaou-stained smears.     

Diagnostic significance of coexpression of intermediate filaments in fine needle aspirates of human tumors

A study was undertaken of the diagnostic significance of the coexpression of intermediate filaments in fine needle aspirates of human tumors. Three types of coexpression were found: (1) true coexpression, in which tumor cells simultaneously express more than one intermediate filament protein; (2) pseudocoexpression, in which various tumor cell types from histogenetically different parts of a complex tumor show different results; and (3) false coexpression, in which tumor cells with one or two types of intermediate filaments are present together with benign cells expressing a different filament type. True coexpression of vimentin and keratin was documented in renal cell carcinomas, endometrial carcinomas, certain thyroid carcinomas and Hürthle cell adenomas. Coexpression of keratin and neurofilaments was seen in Merkel cell carcinomas, and coexpression of desmin and vimentin was found in leiomyosarcomas. Keratin, vimentin and neurofilament expression was seen in medullary thyroid carcinomas, and keratin, vimentin and glial fibrillary acidic protein expression was observed in pleomorphic adenomas of the salivary gland. Pseudocoexpression was noted in synovial sarcoma, epithelioid sarcoma, benign cystosarcoma phyllodes of the breast, teratocarcinoma, malignant granular cell tumor, progonoma, Wilms' tumor and triton tumor. Sources of false coexpression are also discussed.     

Fine needle aspirates of follicular lesions of the thyroid gland. The intermediate-type smear

In order to evaluate fine needle aspirates of thyroid lesions with features intermediate between those of follicular neoplasms and colloid nodules, 38 aspirates in which a definitive diagnosis had not been made were reviewed. On review, ten aspirates were excluded from the "intermediate" category; seven were reclassified as unsatisfactory and one as a cellular colloid nodule. Two papillary carcinomas showed a complex pattern not identified in smears from other lesions; these aspirates were also classified separately for independent evaluation. The remaining 28 aspirates were characterized by syncytial-type tissue fragments with mild nuclear atypia. The association of syncytial-type tissue fragments and orderly sheets and fragments forming a honeycomb pattern in the same aspirate indicated a colloid nodule, though a two-disease process could not be excluded. Of the aspirates containing only syncytial-type tissue fragments, 50% were from adenomas, 25% were from carcinomas, and 25% were from colloid nodules. Criteria to distinguish between the various follicular lesions were not identified in these smears.     

Fine needle aspiration cytology of ductal breast carcinoma with neuroendocrine differentiation. Review of eight cases with histologic correlation

OBJECTIVE: To describe the fine needle aspiration cytology findings of ductal breast carcinoma with neuroendocrine differentiation and correlate them with the histologic appearance. STUDY DESIGN: We reviewed the cytologic features of eight cases of ductal carcinoma with neuroendocrine differentiation in the files of Pamela Youde Nethersole Eastern Hospital during the three-year period 1998-2000. Immunohistochemical study for neuroendocrine markers was performed, with ultrastructural correlation. RESULTS: All cases showed similar cytologic features. The smears were of moderate to high cellularity with predominantly dispersed or loosely cohesive tumor cells. The carcinoma cells were mostly of low cytologic grade. They possessed round and relatively uniform, eccentric nuclei; finely stippled chromatin; sometimes small, distinct nucleoli; and discrete cell borders. Abundant eosinophilic and focally granular cytoplasm was a common finding. In some of the cases there was accentuation of staining in the paranuclear region; it correlated with aggregates of dense core neurosecretory granules seen ultrastructurally. Mucoid substance was seen in the background in some of the aspirates. Histologic examination of the tumors showed invasive ductal carcinoma with an organoid growth pattern and sometimes mucinous component. The neuroendocrine differentiation was confirmed immunohistochemically. CONCLUSION: Although this subtype of ductal carcinoma probably carries no significant prognostic value per se, it has distinct cytologic features, rendering preoperative diagnosis possible. Recognition of this entity is important in order to avoid the misdiagnosis of neuroendocrine tumor metastatic to the breast.     

Primary cecal lymphoma. Report of a case with preoperative diagnosis by fine needle aspiration and immunocytochemistry.

Fine needle aspiration of a cecal mass was performed on a patient with a cecal tumor and iron-deficiency anemia. Cytologic studies of the air-dried smears showed large cell lymphoma. The diagnosis of large cell lymphoma of the B-cell type was affirmed by immunocytochemical studies and at laparotomy and resection of the tumor. Even under unusual circumstances, the diagnosis of such a rare abdominal lesion as primary cecal lymphoma can be made with certainty by cytologic and immunologic studies of fine needle aspirates.     

Immunochemical demonstration of keratin and vimentin in cytologic aspirates

Antibodies to intermediate filament proteins were used to characterize tumor cells present in peritoneal and pleural effusions and in thin needle aspirates from palpable lymph nodes. Metastatic adenocarcinoma cells (breast, ovary, endometrium, cervix, colon and stomach) as well as squamous-cell carcinomas and mesotheliomas stained specifically with antibodies to keratin while mesenchymally derived tumor cells (lymphomas, melanoma, fibrosarcoma and neurofibrosarcoma) were positive only for vimentin. Especially in cases of lymph node aspirates, keratin staining in cells was a direct indication of metastatic carcinoma. Antibodies to these different components of the cytoskeleton can thus be used in cytopathologic diagnosis when a definitive diagnosis cannot be made on the basis of conventional cytologic features.     

Mast cells in the aspiration cytology differential diagnosis of adenolymphoma

Review was undertaken of 20 cases of adenolymphoma (Warthin's tumor) of the salivary glands diagnosed by fine needle aspiration (FNA). Smears of the aspirates from 16 of the 20 cases (80%) contained mast cells associated with monolayered sheets of oncocytes. Aspiration smears from control cases showed cells in significantly fewer instances: 10% of the cases of mucoepidermoid carcinoma, 5% of the cases of pleomorphic adenoma and none of the cases of acinic-cell tumor, squamous-cell carcinoma and branchial cysts. Mast cells in association with oncocytes thus should be considered supportive evidence of an FNA diagnosis of adenolymphoma.     

Endogenous phosphatase activity in tumor cells in a liver aspirate. A potential problem for immunocytodiagnosis using immunoalkaline phosphatase methods

Immunocytochemical studies were performed on fine needle aspirates of the liver in a patient with hepatocellular carcinoma. A panel of commercially available antibodies was used to study the aspirated cells by immunoalkaline phosphatase and immunoperoxidase methods. The malignant cells in the aspirates, which were positively stained by the immunoperoxidase method for alphafetoprotein and by both methods for epithelial membrane antigen, were most probably hepatocellular in origin. Some cells were shown by the immunoalkaline phosphatase method to possess leukocyte-common antigen (LCA) and antigens of colonic and ovarian tissues. These findings were further investigated, and it was found that the tumor cells indeed had LCA as well as levamisole-resistant alkaline phosphatase activity. Although the immunoalkaline phosphatase methods are useful immunodiagnostic techniques applicable to fine needle aspirates, the endogenous enzyme activity present in some nonhematopoietic tumor cells is a cause for caution in the use of these methods in aspirates from nonhematopoietic tumor tissues.     

Hepatic metastases from the spindle cell variant of medullary thyroid carcinoma: report of a case with diagnosis by fine needle aspiration biopsy.

BACKGROUND: The liver is a common site of neuroendocrine tumors (NTs) metastatic from primaries in the gastrointestinal tract, pancreas, biliary system and lungs. Medullary thyroid carcinoma (MTC) is also a potential source of metastases of NTs. Their metastases to the liver are frequent and can appear several years after the primitive tumor. Although a wide variety of cytomorphologic features are normally exhibited by MTC in smears, a spindle-shaped cell pattern can predominate, complicating the correct interpretation of a metastasis. CASE: A 63-year-old man presented with multiple liver nodules two years after a total thyroidectomy for MTC. Fine needle aspiration biopsy smears of the liver revealed neoplastic cells occurring in loose groupings or lying singly, most of them with a spindle shape and elongated nucleus with the characteristic "salt and pepper" chromatin pattern of a neuroendocrine tumor. Cytoplasmic dendritic processes and intranuclear inclusions were frequently seen. The cytomorphologic features of the tumor were essentially the same as those of the primary MTC. Immunoreactivity for calcitonin confirmed the diagnosis. CONCLUSION: In fine needle aspiration biopsy of liver masses, knowledge of the spindle pattern of the NT is important in order to achieve a correct diagnosis when metastases are the first manifestation of an occult primary tumor. Among neuroendocrine tumors, MTC must be included in the differential diagnosis.     

Pseudoepithelial pattern in smears prepared from fine needle aspirates of plasmacytomas

A pseudoepithelial pattern was observed in smears prepared from fine needle aspirates (FNA) from three plasmacytomas. In one case cells displayed a markedly granular, 'oncocytic' cytoplasm. Granularity of the cytoplasm was due to a large number of mitochondria as shown by electron microscopy. B-lymphocytic origin of the neoplasms was confirmed by immunocytochemistry.     

Stereologic estimates of volume-weighted mean nuclear volume in aspiration smears of ductal breast carcinoma. Correlation with cytologic grade, tumor size and lymph node status

OBJECTIVE: To estimate cytologic volume-weighted mean nuclear volume and correlate it with other prognostic factors, such as tumor diameter and cytologic grading in relation to nodal infiltration. STUDY DESIGN: The relationships between nodal status and nuclear VV, tumor diameter and cytologic grading, according to the modified Black nuclear grading system, were analyzed on fine needle aspirates of 49 cases of breast cancer by univariate and multivariate logistic regression. RESULTS: Volume-weighted mean nuclear volume (nuclear VV) estimated on fine needle aspiration smears showed a significant correlation with grade of tumor differentiation. CONCLUSION: Stereologic evaluation of nuclear size by nuclear VV is an objective method for the cytologic grading of ductal carcinoma of the breast and has independent prognostic value in relation to nodal status higher than those of tumor diameter and cytologic grade.     

Parotid metastasis of Merkel cell carcinoma in a young patient with ectodermal dysplasia. Diagnosis by fine needle aspiration cytology and immunocytochemistry.

Fine needle aspiration (FNA) biopsy was performed on an intraparotid lymph node metastasis of a Merkel cell carcinoma of the eyelid in a 15-year-old girl with antecedent ectodermal dysplasia syndrome. The cytologic appearance of the aspirate and the results of immunocytochemical typing of intermediate filaments on the FNA smears provided a definitive diagnosis. The Romanowsky stain provided an excellent delineation of paranuclear intracytoplasmic "buttons," which appeared to contain both cytokeratin and neurofilaments by immunocytochemical studies. These findings confirm previous data emphasizing the role of light microscopic observations, supplemented by proper immunocytochemical investigations, in the differential diagnosis of metastatic Merkel cell carcinoma in fine needle aspirates.