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Trogocytosis is an underappreciated phenomenon that shapes the immune microenvironment surrounding many types of solid tumors. The consequences of membrane-bound proteins being deposited from a donor immune cell to a recipient cancer cell via trogocytosis are still unclear. Here, we report that human clear cell renal carcinoma tumors stably express the lymphoid markers CD45, CD56, CD14, and CD16. Flow cytometry performed on fresh kidney tumors revealed consistent CD45 expression on tumor cells, as well as varying levels of the other markers mentioned previously. These results were consistent with our immunofluorescent analysis, which also revealed colocalization of lymphoid markers with carbonic anhydrase 9 (CAIX), a standard kidney tumor marker. RNA analysis showed a significant upregulation of genes typically associated with immune cells in tumor cells following trogocytosis. Finally, we show evidence of chromosomal DNA being transferred from immune cells to tumor cells during trogocytosis. This horizontal gene transfer has transcriptional consequences in the recipient tumor cell, resulting in a fusion phenotype that expressed both immune and cancer specific proteins. This work demonstrates a novel mechanism by which tumor cell protein expression is altered through the acquisition of surface membrane fragments and genomic DNA from infiltrating lymphocytes. These results alter the way in which we understand tumor-immune cell interactions and may reveal new insights into the mechanisms by which tumors develop. Additionally, further studies into trogocytosis will help push the field towards the next generation of immunotherapies and biomarkers for treating renal cell carcinoma and other types of cancers.

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Paraneoplastic syndromes can precede the initial manifestation and diagnosis of cancer. Paraneoplastic syndromes are a heterogeneous group of disorders caused by mechanisms other than the local presence of tumor cells. These phenomena are mediated by humoral factors secreted by tumor cells or by tumor mediated immune responses. Among paraneoplastic syndromes, chronic intestinal pseudo-obstruction (CIPO) is rare and represents a particularly difficult clinical challenge. Paraneoplastic CIPO is a highly morbid syndrome characterized by impaired gastrointestinal propulsion with symptoms and signs of mechanical bowel obstruction. Clinical outcomes of paraneoplastic CIPO are often deleterious. The current standard of care for the management of CIPO includes supportive treatment with promotility and anti-secretory agents. However, the majority of patients with CIPO eventually require the resection of the non-functioning gut segment. Here, we present a 62-year-old patient with anti-Hu antibody associated paraneoplastic CIPO and underlying small cell lung cancer who underwent treatment with cisplatin and etoposide. Herein, we discuss diagnosis, prognosis, proposed mechanisms, treatment options, and future potential therapeutic strategies of paraneoplastic CIPO.

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Giant-cell tumor of the bone (GCTB) is a rare neoplasm that affects young adults. The tumor is generally benign but sometimes can be locally aggressive. There are no standardized approaches to the treatment of GCTB. Recently, the RANKL inhibitor denosumab has shown activity in this tumor type. We present the case of a young female who presented with locally advanced disease and was successfully managed with the neoadjuvant use of denosumab allowing for surgical resection of the tumor that was previously deemed unresectable. Following surgery, the patient is being managed with continued use of denosumab as 'maintenance,' and she continues to be free of disease. Our case highlights a novel approach for the management of locally advanced and aggressive giant cell tumor of the bone.

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The behavior of littoral cell neoplasms ranges from benign (littoral cell angioma, LCA) to highly malignant (angiosarcoma). Two unusual cases of low-grade metastatic littoral cell angiosarcoma (LCAS) have been reported with late recurrence and bulky metastases. We present the third case of this rare neoplasm in a 38-year-old man with cirrhosis and a large splenic artery aneurysm, without extrasplenic masses. The spleen showed nodules resembling LCA, immunoreactive for CD31, factor VIII, CD68, and CD163 but not CD8 or CD34. Also present were solid areas of immunophenotypically identical bland spindle cells, although lighter CD31 immunostaining distinguished them from LCA-like angiomatous channels. Similar cells diffusely infiltrated the cirrhotic liver. After splenectomy, pancytopenia resolved, and he is asymptomatic 19 months later. Low-grade LCAS is a previously unreported cause of cirrhosis and may metastasize without forming masses. In cases of LCA, CD31 immunohistochemistry may facilitate detection of LCAS and indicate metastatic potential.

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Iron homeostasis is crucial to normal cell metabolism, and its deficiency or excess is associated with numerous disease states. The association of increased iron load with cancer may be due to several factors including free radical production, reduction of the body's protective mechanism to combat oxidative stress, inhibition of immune systems, inhibition of essential nutrient functions, facilitation of cancer growth, suppression of antitumor actions of macrophages, and lowering of the ratio of T4-T8 positive lymphocytes. Antiproliferative effects of desferoxamine (DFO) both in vitro and in vivo are mediated by an intracellular pool of iron that is necessary for DNA synthesis rather than prevention of iron uptake from transferrin. Several clinical studies have shown it to have antitumor activity in the treatment of neuroblastoma, leukemia, bladder carcinoma, and hepatocellular carcinoma. Human neural tumor cells are susceptible to the effects of DFO. Continued study of DFO is necessary to further elucidate its antineoplastic profile and its use as an adjunct to current chemotherapy regimens. Given the lack of satisfactory treatment of central nervous system neoplasms, DFO could serve as an important tool in the management of such cancers.

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