ATF1, CREB1, and CREM constitute the CREB family of transcription factors. The genes encoding these factors are involved in gene fusion events in human tumors. EWSR1-ATF1 and EWSR1-CREB1 are the 2 most characterized fusions, whereas EWSR1-CREM has been less studied. To better understand the phenotypic spectrum of mesenchymal tumors associated with the EWSR1-CREM fusion, we investigated archival cases using fluorescence in situ hybridization and/or RNA sequencing. Among 33 clear cell sarcomas of soft tissue tested, we found 1 specimen, a hand tumor bearing the rearrangements of EWSR1 and CREM, with classic histology and immunophenotype. None of 6 clear cell sarcoma-like tumors of the gastrointestinal tract tested harbored the EWSR1-CREM fusion. Among 11 angiomatoid fibrous histiocytomas, we found that 3 tumors of myxoid variant harbored the rearrangements of EWSR1 and CREM. All 3 tumors occurred in middle-aged men and involved the distal extremities (N=2) and the lung (N=1). Prominent lymphoid cuff, fibrous pseudocapsule, and amianthoid fiber were present in 3, 2, and 2 tumors, respectively, whereas none showed pseudoangiomatoid spaces. All 3 tumors were immunohistochemically positive for epithelial membrane antigen and desmin. These cases suggested a closer relationship between angiomatoid fibrous histiocytoma and a recently proposed novel group of myxoid tumors with CREB family fusions. Our cohort also included 2 unclassifiable sarcomas positive for EWSR1-CREM. One of these was an aggressive pediatric tumor of the abdominal cavity characterized by proliferation of swirling spindle cells immunopositive for cytokeratin and CD34. The other tumor derived from the chest wall of an adult and exhibited a MUC4-positive sclerosing epithelioid fibrosarcoma-like histology. Our study demonstrates that a wider phenotypic spectrum is associated with the EWSR1-CREM fusion than previously reported.

Purposes: Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) has been widely used for the diagnosis of pancreatic cancer. Because autoimmune pancreatitis is easily misdiagnosed as pancreatic cancer and can be tested for by FDG-PET analysis based on the presence of suspected pancreatic cancer, we attempted to clarify the differences in FDG-PET findings between the two conditions. Methods: We compared the FDG-PET findings between 15 patients with autoimmune pancreatitis and 26 patients with pancreatic cancer. The findings were evaluated visually or semiquantitatively using the maximum standardized uptake value and the accumulation pattern of FDG. Results: FDG uptake was found in all 15 patients with autoimmune pancreatitis, whereas it was found in 19 of 26 patients (73.1%) with pancreatic cancer. The accumulation pattern of nodular shape was frequently seen in pancreatic cancer with significance, whereas a longitudinal shape indicated the existence of autoimmune pancreatitis. Heterogeneous accumulation was found in almost all cases of autoimmune pancreatitis, whereas homogeneous accumulation was found in pancreatic cancer. Most cases of pancreatic cancer showed solitary localization with significant difference, whereas multiple localizations in the pancreas favored the existence of autoimmune pancreatitis. FDG uptakes in the hilar lymph node were more frequently seen in autoimmune pancreatitis than in pancreatic cancer with significance, and those in the lachrymal gland, salivary gland, biliary duct, retroperitoneal space, and prostate were only seen in autoimmune pancreatitis. Conclusions: FDG-PET provides a useful tool for differentiating autoimmune pancreatitis from suspected pancreatic cancer, if its accumulation pattern and extra-pancreatic involvements are considered. IgG4 measurement and other current image tests will confirm further diagnosis.

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3080 (w), 2910 (vw), 1440 (m), 1010 (s), 910 (w), 785 (vs) 468 (26.4), 433 (2.3), 403 (100), 368 (3.0), 338 (95.8), 303 (2.2), 273 (12.5) UCp3 79Br 3.72 3101 (w), 2925 (vw), 1440 (s), 1360 (w), 1264 (vw), 1218 (vw), 1064 (vw), 918 (m), 824-780 (vs) 512 (38.8), 447 (81.2), 382 (100), 368 (3.5), 319 (8.21), 317 (9.4), 303 (3.5) UCp3I C 31.48 (32.14) 4.36 3100 (w), 2924 (vw), 1440 (s), 1360 (w), 1264 (vw), 1218 (vw), 1070 (m), 1016 (s), 910 (m), 826-780 (vs) 560 (47.6), 495 (64.3), 433 (76.2), 430 (83.3), 368 (100), 303 (40.5) 0 Calculated values in parentheses. 6 Me"Si as internal standard. c KBi pellet. In cm'1. d Relative intensities in parentheses.

We report on a case of a stromal tumor, similar to a gastrointestinal stromal tumor, originating from the pancreas. The patient was a 54-year-old woman, who was seen at the Kofu Municipal Hospital because of an abdominal tumor. On abdominal computed tomography and splenic arteriography, the tumor was detected in the pancreatic tail. The patient underwent distal pancreatectomy with splenectomy. Macroscopically, the cut surface of the tumor showed almost completely surrounded by the normal pancreatic tissue. Microscopically, the tumor composed of spindle-shaped cells that were immunoreactive for vimentin, CD34, and c-kit protein. Therefore, the tumor was diagnosed as a stromal tumor of the pancreas. The expression of c-kit protein suggests that this pancreatic stromal tumor may originate from primitive mesenchymal cells which can be a logical candidate for the origin of gastrointestinal stromal tumors and extra-gastrointestinal stromal tumors.