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Background: Chronic myeloid leukemia (CML) is usually diagnosed in the chronic phase. An extramedullary blast crisis mimicking a T-cell lymphoma is a rare finding. Case Report: A 35-year-old man presented with multiple lymphadenopathy 2 months after diagnosis of Philadelphia chromosome (Ph)-positive CML in the chronic phase. Cervical lymph node biopsy later indicated an extramedullary blast crisis resembling T-cell lymphoblastic lymphoma (TLBL). The tumor mass was composed of primitive lymphoid cells expressing terminal deoxynucleotidyl transferase (TdT), CD3, CD43, CD5, CD99, and Bcl-2. Although the pathological diagnosis, confirmed by 2 independent pathological centers, was more typical of TLBL, fluorescence in situ hybridization (FISH) analysis showed the bcr-abl fusion gene within the blastic tumor cells. The FISH finding confirmed that the mass represented an extramedullary, immature blastic transformation of CML rather than a de novo T-cell lymphoma. Conclusion: The diagnosis of de novo TLBL should be suspected before excluding the extramedullary blast phase of CML.

Reports of thrombosis post coronavirus disease 2019 (COVID-19) mRNA vaccination have sparked concerns about the safety of these immunizations. As of October 31, 2021, the Health Sciences Authority of Singapore reported 13 suspected cases of cerebral venous thrombosis (CVT) with the Pfizer-BioNTech/Comirnaty (BNT162b2) and Moderna/Spikevax (mRNA-1273) COVID-19 vaccines out of 9 953 673 total number of doses administered. 1 We previously reported on three patients who developed CVT post BNT162b2 vaccination, occurring 1-9 days after the second dose. 2 Compared to vaccine-induced thrombotic thrombocytopenia (VITT) associated with the use of adenovirus vector ChAdOx1 nCoV-19 and Ad26.COV2.S COVID-19 vaccines, these patients with CVT CORRESPONDENCE E141

1056 Background: It is well known that microenvironment plays an important role in tumor progression so we investigated the regulatory effects of breast cancer stromal cells (BCSCs) and normal breast stromal cells (NBSCs) as microenvironment on MCF-7 mammosphere formation. Methods: MCF-7 cells were cultured in suspension to generate mammospheres. The proportion of CD44+CD24- cells was assessed by flow cytometry and the expression of Wint1, notch1, β-catenin, CXCR4, SOX2, and ALDH3A1 was detected by real-time PCR. The stromal cells were purified and identified by immumohistochemistry. BCSCs or NBSCs and MCF-7 cells were co-cultured via Transwell system, the volumes and numbers of mammospheres and the mammosphere-forming efficiency (MFE) were calculated and the expression of Wnt1, β-catenin, Notch1 were detected. Results: The proportion of CD44+CD24- cells in mammospheres and MCF-7 cells was 10.4% and 2.1% (p < 0.05), respectively. Real-time PCR analysis suggested that Wint1, notch1, β-catenin, CXCR4, SOX2, and ALDH3A1 genes in the mammosphere cells were with higher levels than MCF-7 cells by about 2.25, 2.45, 1.72, 4.68, 4.25, 5.38 fold, respectively (p < 0.01). The stromal cells purified were identified as fibroblasts by α-SMA,Vimentin and fibroblast special protein antibody via immumohistochemistry. The time of mammosphere's formation was earlier, the volumes of mammospheres were bigger, and the MFE was higher than control group. The expressions of Wnt1 in co-culture group were significantly upregulated 1.27, 3.18 folds than control group, respectively, while the β-catenin was 1.22, 1.75 folds; Notch1 was 1.31, 2.09 folds; and CXCR4 was 1.73, 2.77 folds, respectively. Conclusions: Mammosphere cells contained higher propotion of breast cancer stem cells and expressed higher levels of cancer stem cell related genes. BCSCs can promote the mammosphere-forming efficiency and upregulate the expression of cancer stem cell related genes. No significant financial relationships to disclose.

Background The receptor for activated C kinase 1 (RACK1) expression is associated with clinicopathological characteristics and the prognosis of various cancers; however, the conclusions are controversial. As a result, this study aimed to explore the clinicopathological and prognostic values of RACK1 expression in patients with cancer. Methodology PubMed, Embase, Web of Science, Cochrane Library, and Scopus were comprehensively explored from their inception to April 20, 2023, for selecting studies on the clinicopathological and prognostic role of RACK1 in patients with cancer that met the criteria for inclusion in this review. Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were used to assess the prognosis-predictive value of RACK1 expression, while pooled odds ratios (ORs) and 95% CIs were used to evaluate the correlation between RACK1 expression and the clinicopathological characteristics of patients with cancer. The quality of the included studies was evaluated using the Newcastle-Ottawa Scale. Results Twenty-two studies (13 on prognosis and 20 on clinicopathological characteristics) were included in this systematic review and meta-analysis. The findings indicated that high RACK1 expression was significantly associated with poor overall survival (HR = 1.62; 95% CI, 1.13–2.33; P = 0.009; I2 = 89%) and reversely correlated with disease-free survival/recurrence-free survival (HR = 1.87; 95% CI, 1.22–2.88; P = 0.004; I2 = 0%). Furthermore, increased RACK1 expression was significantly associated with lymphatic invasion/N+ stage (OR = 1.74; 95% CI, 1.04–2.90; P = 0.04; I2 = 79%) of tumors. Conclusions RACK1 may be a global predictive marker of poor prognosis in patients with cancer and unfavorable clinicopathological characteristics. However, further clinical studies are required to validate these findings.