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Nuclear translocation of beta-catenin has been correlated with epidermal growth factor receptor (EGFR) overexpression/activation in non-small cell lung cancer. Less is known on beta-catenin transactivation in high-grade pulmonary neuroendocrine tumors and on the status of beta-catenin activating EGFR and human epidermal growth factor receptor 2 (HER-2) or beta-catenin target genes cyclin D1 and matrix metalloproteinase-7 (MMP-7). beta-catenin immunoreactivity was evaluated in 51 large-cell neuroendocrine carcinomas (LCNEC) and 45 small-cell lung carcinomas (SCLC). Nineteen cases were assessed for beta-catenin gene exon 3 mutations, expression of MMP-7, and expression/gene amplification of EGFR, HER-2, and cyclin D1. beta-catenin was expressed in all 96 high-grade neuroendocrine tumors, the vast majority (94%) showing >50% immunopositive cells. A disarrayed immunoreactivity, however, was commonly encountered consisting in variably altered membrane-associated patterns of staining along with progressive accumulation of cytoplasmic immunoreactivity. In LCNEC, but not in SCLC, the disarrayed patterns correlated with EGFR and HER-2 protein expression. beta-catenin nuclear accumulation was found in nine tumors, including seven LCNEC and two SCLC, and was always associated with disarrayed immunoreactivity and increased MMP-7, but not cyclin D1 expression. These cases, however, did not show beta-catenin gene mutations or EGFR and HER-2 gene amplification or expression. No association was found between nuclear beta-catenin and any clinicopathological variable including patients' survival. The subcellular compartmentalization of beta-catenin is profoundly altered in high-grade pulmonary neuroendocrine tumors. A minor subset of these tumors shows beta-catenin nuclear accumulation in association with increased expression of MMP-7, but not of cyclin D1, independent of EGFR and HER-2 gene amplification or expression. [ABSTRACT FROM AUTHOR]

Little is known about CD117 prevalence and clinicopathological implications in pulmonary large-cell neuroendocrine carcinoma. We studied CD117 immunoreactivity in surgical specimens from 39 large-cell neuroendocrine carcinomas of stages I-III and 27 limited-disease small-cell carcinomas, 56 typical and atypical carcinoids of the lung, and 10 neuroendocrine tumorlets, including the membrane and cytoplasmic immunostaining patterns. Membrane CD117 immunoreactivity in 5% or more tumor cells was documented in 30 (77%) large-cell neuroendocrine carcinomas and 18 (67%) small-cell carcinomas and 4 (7%) carcinoids, whereas cytoplasmic labeling was seen in 17 (44%) large-cell neuroendocrine carcinomas, 19 (70%) small-cell carcinomas, and 3 (5%) carcinoids. None of the neuroendocrine cells of the normal bronchial epithelium and of 10 tumorlets showed any CD117 immunoreactivity. Cytoplasmic immunostaining was more prevalent in small-cell carcinomas, whereas membrane labeling did not differ between the two types of high-grade carcinomas. Downregulation of CD117 by neoadjuvant chemotherapy was seen in large-cell neuroendocrine carcinomas but not small-cell carcinomas. Multiple linear regression analysis demonstrated a marginal association between cytoplasmic CD117 immunoreactivity and regional lymph node metastasis in small-cell carcinomas but not large-cell neuroendocrine carcinomas. There was no association between CD117 immunoreactivity and survival in either small-cell carcinoma or large-cell neuroendocrine carcinoma patients. [ABSTRACT FROM AUTHOR]

Extranodal follicular dendritic cell sarcoma (FDCS) is an extremely uncommon tumor with only a single case arising in the breast having been reported. We describe the clinico-pathological features of an additional FDCS of the lower outer quadrant of the right breast in a 40-year-old woman. The tumor showed three patterns of growth, i.e., diffuse, myxoid and fascicular. The neoplastic cells were large, polygonal, with a slightly eosinophilic cytoplasm and oval or convoluted nuclei. They were intermingled with small lymphocytes, plasma cells and a few bizarre multinucleated giant cells. In the fascicular areas, the cells were spindled, while in the myxoid areas they showed a dendritic-like appearance, with long cytoplasmic processes. Mitoses were numerous and often atypical. The neoplastic cells were intensely immunoreactive for CD21, S-100 protein and epithelial membrane antigen, and focally for CD35, CD68 and cytokeratins. Polymerase chain reaction analysis did not reveal any Epstein Barr virus genome in the neoplastic tissue. Electron microscopy highlighted numerous interdigitating cytoplasmic processes with intercellular junctions of the serrated, immature desmosomal or undifferentiated types. The post-surgical course of the patient was uneventful and she is currently free of disease 19 months after surgery. [ABSTRACT FROM AUTHOR]