The c-kit proto-oncogene encodes a receptor tyrosine kinase that is thought to play an important role in hematopoiesis. In a series of human acute myeloblastic leukemia (AML), the expression of the c-kit proto-oncogene and its product was studied by means of Northern blot and immunoblot analyses. The c-kit mRNA was expressed in 20 of 25 cases of AML, and in those cases the product of the c-kit proto-oncogene was detected by immunoblotting with anti-c-kit antibody. The expression of c-kit transcripts and protein was barely detectable in normal bone marrow cells as a control. The expression of c-kit transcript did not correlate with the French-American-British classification nor clinical manifestations. In 6 of 11 cases that expressed c-kit product, AML cells were found to proliferate in response to recombinant human stem cell factor (rhSCF), the ligand for c-kit, and the synergistic stimulation of AML cells was observed by rhSCF and granulocyte- macrophage colony-stimulating factor. Immunoblotting with anti- phosphotyrosine antibody showed that the c-kit receptor protein was detectably phosphorylated in 7 of 12 cases tested before the stimulation with rhSCF, while the rhSCF treatment resulted in an increased tyrosine phosphorylation of c-kit in AML cells. These results indicate that c-kit proto-oncogene is expressed in most cases of AML and is functional in terms of supporting proliferation.

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Undifferentiated sarcoma harboring the BCOR-CCNB3 fusion is characterized by its predilection to affect skeletons of adolescent males, cellular small round/spindle cell morphology, and CCNB3 immunoreactivity. We analyzed 11 cases of BCOR-CCNB3 sarcoma, 10 of which were identified in a reverse transcription-polymerase chain reaction-based screen of 85 patient samples recorded in our database as unclassified small round or spindle cell sarcomas. BCOR rearrangements were confirmed by fluorescence in situ hybridization in 8 tumors. All patients were males aged between 6 and 31 years. In addition to 5 tumors in soft tissue and 4 in the axial or appendicular skeletons, which are typical locations, a tumor was located in the paranasal sinus and another in the lung. Microscopically, the tumors comprised proliferating atypical spindle and/or small round cells with diverse morphologic features such as small concentric whorls, myxoid stroma, a hemangiopericytomatous appearance, and/or hyalinized collagen resembling a solitary fibrous tumor, and angiomatous or slit-like spaces containing extravasated erythrocytes. Tumor cells were immunoreactive to CCNB3 (9/11), BCOR (10/10), TLE1 (6/10), bcl-2 (9/11), CD99 (8/10), CD56 (8/10), c-kit (4/10), and cyclin D1 (10/10). In an immunohistochemical analysis of an additional 412 small round or spindle cell tumors, CCNB3 was detected in 6 (1.5%) and BCOR in 18 (4.4%). Our analysis highlights the varying clinicopathologic features of this tumor, which partially overlap with other small round or spindle cell tumors, including solitary fibrous tumor and vascular tumors. Because CCNB3 and BCOR immunohistochemistry lacks adequate sensitivity and specificity, a molecular genetic approach remains essential for diagnosis.

BackgroundA report of multiple cases of bile duct cancer at a Japanese printing company raised concern about such cancers. We examined long-term trends in bile duct cancer in Japan.MethodsData from 4 population-based cancer registries were used to calculate incidence between 1985 and 2007, and vital statistics were used to estimate mortality between 1985 and 2011. Age-standardized rates were calculated and analyzed using a joinpoint regression model.ResultsAmong men, the incidence rate of intrahepatic bile duct cancer increased throughout the observation period; among women, it increased until 1996–1998 and remained stable thereafter. The incidence rate of extrahepatic bile duct cancer was stable in men and decreased from 1993–1995 in women. In people aged 30 to 49 years, the incidence rates of intra- and extrahepatic bile duct cancer remained stable or decreased. The mortality rate of intrahepatic bile duct cancer increased in both sexes and in all age groups since 1996, while that of extrahepatic bile duct cancer decreased since 1992. In people aged 30 to 49 years, the mortality rates of intra- and extrahepatic bile duct cancer remained stable and decreased, respectively.ConclusionsThe incidence and mortality rates of intrahepatic bile duct cancer remained stable or increased throughout the observation period. The incidence rate of extrahepatic bile duct cancer remained stable or decreased, and the mortality rate decreased since 1992. In people aged 30 to 49 years, the incidence and mortality rates of intra- and extrahepatic bile cancer remained stable or decreased.