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We investigated the quantification of Ki-67 staining using digital image analysis (IA) as a complementary prognostic factor to the modified National Institutes of Health (NIH) classification in patients with gastrointestinal stromal tumor (GIST). We examined 92 patients, focusing on the correlation between age, sex, primary tumor site, tumor size, predominant histologic type, mitotic index, modified NIH classification (low/intermediate vs high), Ki-67 quantitation, and recurrence-free survival (RFS). We compared two IA processes for whole slide imaging (WSI) and manually captured image (MCI) methods. A Ki-67 quantitation cutoff was determined by receiver operator characteristics curve analysis. In the survival analysis, the high-risk group of a modified NIH classification, a mitotic count >5 per 20 high-powered fields, and Ki-67 cutoffs of ≥6% and ≥8% obtained by IA of the WSI and MCI methods, respectively, had an adverse impact on RFS. On multivariate analysis, each Ki-67 quantitation method strongly predicted prognosis, more strongly than the modified NIH classification. In addition, Ki-67 quantitation using IA of the MCI method could stratify low or intermediate risk and high risk GIST patients. Thus, IA is an excellent tool for quantifying Ki-67 to predict the prognosis of GIST patients, and this semiautomated approach may be preferable for patient care.

Fluorescence in situ hybridization (FISH) is an essential tool for genetic diagnosis in daily pathological work. Almost full automation of FISH can be achieved with the recently released automated SureFISH platform (Dako Omnis, Agilent Technologies, Santa Clara, CA, USA). Its utility has been reported in HER2 amplification of breast and gastric carcinoma and ALK-rearranged lung cancer. Here, we examined the utility of automated SureFISH for the identification of rearrangement signals in translocation-related sarcomas (TRSs), including 11 EWSR1-rearranged and 10 synovial sarcoma cases, compared with non-automated conventional FISH using the same specimens. The percentages of EWSR1 or SS18 split signals were higher in automated SureFISH than in conventional FISH in 13 of the 21 cases. On the other hand, 8 of the 21 cases showed the same or lower percentage of split signals in automated SureFISH. Both FISH approaches detected EWSR1 and SS18 split signals in more than 10% of tumor cells in all cases. The strongest advantage of automated SureFISH is its ability to reduce running time without sacrificing quality. Other advantages include improved signal sharpness with oligo probes and reduced ecological toxicity by avoiding formamide use. Automated SureFISH is an excellent tool for the genetic diagnosis of TRSs and contributes to their rapid definitive diagnosis.

Background Clear cell sarcoma of soft tissue (CCSST) and clear cell sarcoma-like gastrointestinal tumor (CCSLGT) are malignant mesenchymal tumors that share some pathological features, but they also have several different characteristics. They are well known to express chimeric fusions of Ewing sarcoma breakpoint region 1 (EWSR1) and cAMP response element-binding protein (CREB) family members; namely, EWSR1-activating transcription factor 1 (ATF1) and EWSR1-CREB1. In addition, recent studies have suggested the presence of other fusions. Methods We used fluorescence in situ hybridization to detect specific rearrangements including EWSR1, ATF1, CREB1, and cAMP response element modulator (CREM) in 16 CCSST and 6 CCSLGT cases. We also used reverse transcription polymerase chain reaction (RT-PCR) to detect specific chimeric fusions of EWSR1-ATF1 and EWSR1-CREB1 using fresh tumor samples in available cases. Results A total of 15 of 16 CCSST cases (93.8%) had EWSR1 rearrangement, of which 11 (68.8%) also had ATF1 rearrangement, suggestive of the presence of EWSR1-ATF1 fusions. One CCSST case (6.3%) was found to have EWSR1 and CREM rearrangements, and 4 of 6 CCSLGT cases (66.7%) had EWSR1 rearrangement, of which 2 (33.3%) showed ATF1 rearrangement and the other 2 cases (33.3%) showed CREB1 rearrangement. These cases most likely had EWSR1-ATF1 and EWSR1-CREB1 fusions, respectively. RT-PCR was performed in 8 available cases, including 6 CCSSTs and 2 CCSLGTs. All CCSSTs showed EWSR1-ATF1 fusions. Among the 2 CCSLGT cases, one had EWSR1-ATF1 fusion and the other had EWSR1-CREB1 fusion. Conclusions Rearrangements of EWSR1 and ATF1 or EWSR1-ATF1 fusion were predominantly found in CCSST, whereas those of EWSR1 and CREB1 or EWSR1-CREB1 tended to be detected in CCSLGT. A novel CREM fusion was also detected in a few cases of CCSST and CCSLGT. The cases in which EWSR1 rearrangement was detected without definitive partner genes should be considered for the presence of CREM rearrangement.

Background Uterine sarcoma is a rare tumor that is often difficult to classify based on morphological and immunohistochemical analysis alone. Limited access to molecular biological analysis in routine practice would hinder making a definitive diagnosis. Case Presentation In this report, we describe a case of a mesenchymal tumor arising from the uterine cervix in a 52-year-old woman. From microscopic morphology of the resected specimen, epithelioid leiomyosarcoma, high-grade endometrial stromal sarcoma, or uterine gastrointestinal stromal tumor (GIST) were considered as differential diagnoses. The immunophenotype of the tumor featured smooth muscle differentiation and hormone receptor expression. The cell membrane and cytoplasm were positive for c-kit, although no mutation was found in the c-kit or PDGFRA gene. Fluorescence in situ hybridization (FISH) analysis revealed a relatively low frequency of YWHAE rearrangement, whereas there were few NUTM2A and NUTM2B split signals. Conclusions In this case, the tumor was not typical of any three of the differential diagnoses mentioned above. However, insufficient frequency of YWHAE, NUTM2A, and NUTM2B gene rearrangement and absence of mutation in both the c-kit and PDGFRA genes suggested that this tumor should be categorized as epithelioid leiomyosarcoma. This is an instructive case showing a potential diagnostic pitfall of uterine sarcoma. Comprehensive approaches including molecular biological techniques are required for definitive diagnosis.