Showing papers by "Saul Suster published in 1996"

Primary thymic epithelial neoplasms showing combined features of thymoma and thymic carcinoma. A clinicopathologic study of 22 cases.

Abstract: Thymic epithelial neoplasms are unusual tumors that may span the gamut from clinically benign, well-differentiated lesions (encapsulated thymoma) to overtly malignant, poorly differentiated neoplasms (thymic carcinoma). It has been commonly believed that lesions displaying obvious cytologic features of malignancy (i.e., thymic carcinoma) represent a unique and separate group that is histogenetically distinct from thymoma. We have studied 22 cases of thymic epithelial neoplasms characterized by the admixture of areas displaying conventional features of thymoma with areas showing features of thymic carcinoma. The tumors occurred in six women and 16 men whose ages ranged from 23 to 83 years (median, 53). The lesions presented in eight patients with symptoms of chest discomfort resulting from the involvement of surrounding structures; in 14 patients, they were asymptomatic and discovered incidentally on routine chest radiographs. Histologically, most tumors showed a combination of conventional thymomatous elements with well-differentiated squamous-cell carcinoma (10 cases), followed by thymoma and poorly-differentiated squamous carcinoma (seven cases) and spindle-cell thymoma with poorly-differentiated squamous carcinoma (five cases). Areas of transition between the two different components could be identified in most cases. In five cases, areas showing the features of clear-cell carcinoma could be seen either arising from squamous carcinomatous elements or within the thymomatous component, and in one case transitions between lymphoepithelioma-like carcinoma and anaplastic carcinoma could be observed. Two patients had a history of myasthenia gravis with biopsy-proven thymomas in whom the tumors had been monitored without treatment for 10 and 14 years before the sudden enlargement of the mass. The resected specimens in both patients showed the emergence of a carcinoma arising from a thymoma. The present cases appear to support the existence of a continuum in the spectrum of differentiation between thymoma and thymic carcinoma, suggesting a close histogenetic relationship between these two conditions. Such findings are important not only for our understanding of these tumors but may also play a significant role in the assessment of the biologic behavior and management of these lesions.

The down-regulated in adenoma (DRA) gene encodes an intestine-specific membrane glycoprotein.

Abstract: The protein product of the DRA gene, a gene whose expression is down-regulated in colon adenomas and adenocarcinomas, is a membrane glycoprotein and a member of a family of sulfate transporters. It is expressed in the intestinal tract (duodenum, ileum, cecum, distal colon), but not in the esophagus or stomach. DRA mRNA expression is restricted to the mucosal epithelium, and DRA protein expression is further limited to the columnar epithelial cells, particularly to the brush border. Consistent with its expression in the differentiated columnar epithelium of the adult human colon, DRA is first expressed in the midgut of developing mouse embryos at day 16.5, corresponding with the time of differentiation of the epithelium of the small intestine. A model for the structure of the DRA protein is proposed and its possible role in colon tumorigenesis is discussed.

Benign cutaneous adnexal tumors with combined folliculosebaceous, apocrine, and eccrine differentiation. Clinicopathologic and immunohistochemical study of eight cases.

Abstract: Benign cutaneous adnexal tumors displaying divergent differentiation are rare, with very few well-documented cases reported in the literature. We describe eight cases of benign adnexal tumors showing a variable combination of eccrine, apocrine, and folliculosebaceous differentiation. Clinically, all tumors presented as solitary, slowly enlarging dermal or subcutaneous nodules located in the head and neck and the extremities. Histologically, they were characterized by well-circumscribed, unencapsulated nodules composed of a lobular proliferation of epithelial cells displaying a spectrum of trichogenic, sebaceous, apocrine, and eccrine differentiation. The histological spectrum included lobules and trabeculae of basaloid cells with glandular and ductal elements, well-formed folliculosebaceous units, primitive follicles, and foci of tricholemmal keratinization. Immunohistochemical evaluation in four cases showed similar cytokeratin, carcinoembryonic antigen, and epithelial membrane antigen staining profiles as those reported for sweat gland adenomas; in addition, focal S-100 protein positivity and GCDFP-15 positivity could also be demonstrated, suggesting eccrine-apocrine differentiation. The tumors were most frequently confused histologically with other adnexal neoplasms, including sebaceoma, sebaceous adenoma, basal cell carcinoma, chondroid syringoma, and trichoepithelioma. The present series highlights the capability.

Pleomorphic large cell lymphomas of the mediastinum.

Abstract: Nine cases of primary non-lymphoblastic, non-Hodgkin's large cell lymphomas of the mediastinum characterized by a highly pleomorphic histologic appearance are described. The patients, four women and five men, were aged 30 to 65 years. All patients presented with symptoms referable to their tumors, including cough, chest pain, dyspnea, pleural effusion, and superior vena cava syndrome. Clinical and pathologic staging in all patients showed that the bulk of the tumor was confined to the chest cavity at the time of initial diagnosis, with local infiltration into the neck, lung hilum, and surrounding mediastinal structures. Three different histological growth patterns were observed: one composed of a diffuse proliferation of pleomorphic, highly atypical cells with bizarre nuclear features that closely resembled a high grade sarcoma; another one composed of sheets of large, epithelial-appearing atypical cells suggestive of anaplastic carcinoma; and another pattern characterized by a pleomorphic proliferation of large lymphoid cells admixed with numerous scattered Reed-Sternberg-like cells reminiscent of the lymphocyte-depleted variant of Hodgkin's disease. Immunohistochemical studies on paraffin-embedded tissue sections in all cases showed positive staining of the tumor cells with CD20 and CD45 antibodies and negative staining with a large panel of markers, including broad-spectrum keratin, CAM 5.2, carcinoembryonic antigen, epithelial membrane antigen, vimentin, actin, desmin, HMB 45, S-100 protein, CD3, CD15, CD30, and CD45RO. Because of their location restricted to the anterior mediastinum, frequent lack of recognizable lymph node architecture, and bizarre cytologic features, the present group of lesions posed difficulties for diagnosis, their correct identification was achieved through the application of a panel of immunohistochemical markers. An awareness of these unusual histologic appearances of primary large cell lymphoma in the mediastinum and inclusion of a broad panel of lymphoid markers are therefore recommended for the evaluation of pleomorphic, undifferentiated malignant neoplasms of this anatomic region.

Microglandular carcinoma of the pancreas: immunohistochemical and ultrastructural study of an unusual variant of pancreatic carcinoma that may closely resemble a neuroendocrine neoplasm.

Abstract: Two cases are described of an unusual form of primary adenocarcinoma of the pancreas characterized histologically by their striking resemblance with a neuroendocrine neoplasm. The tumors were composed of a population of relatively small, uniform cells arranged in sheets admixed with small microglandular structures resulting in a cribriform pattern of growth. The tumor cells displayed scant cytoplasm with indistinct cell borders and round to oval nuclei with irregular clumping of chromatin and small, inconspicuous nucleoli. Immunohistochemical studies in both cases showed positivity of the neoplastic cells with CAM 5.2 antibodies and negative staining with a battery of neuroendocrine-related markers including chromogranin, NSE and synaptophysin, as well as with a variety of peptide hormones including insulin, glucagon, vasoactive intestinal polypeptide, gastrin and serotonin. Ultrastructural examination revealed a cohesive population of cells forming abortive glandular lumens lined by imperfectly formed microvilli and showing well-developed junctional complexes. No dense core neurosecretory granules or zymogen granules could be identified in any of the cells, supporting a ductal type of differentiation for these tumors. The main importance of recognizing this rare variant of pancreatic adenocarcinoma lies in avoiding misdiagnosis with other primary and metastatic neuroendocrine neoplasms of this organ. Immunohistochemical and ultrastructural examination will be of value in such cases for differential diagnosis.

Primary thymic carcinomas.

Abstract: Primary thymic epithelial neoplasms are unusual tumors that have been the subject of much interest and debate, and their natural behavior has been difficult to determine In this chapter the authors review current concepts on the classification and criteria for diagnosis of thymic carcinoma