Breast cancer remains a leading cause of cancer-related morbidity and mortality worldwide, driven by therapeutic resistance, recurrence, and metastasis. Patient-derived organoids (PDOs) have emerged as a robust platform that preserves histopathological, genetic, and functional features of parental tumors, enabling translational research and precision oncology. However, the lack of standardized procedures across laboratories limits reproducibility and clinical applicability. Here, we present a consensus-oriented standard for the establishment, characterization, quality control and application of human breast cancer organoids derived from diverse clinical sources, including surgical tissues, biopsies, pleural effusion, ascites, and circulating tumor cells (CTCs). This document defines key terminologies, outlines standardized workflows, and introduces quantitative validation criteria for successful organoid establishment. In addition, it provides structured guidance for advanced models, including immune-tumor, neuro-tumor, and microbiota-tumor organoid systems, with defined functional validation endpoints. Standardized protocols for drug sensitivity testing are also proposed, including seeding density, exposure duration, and response metrics such as IC50 and AUC. Representative validation strategies, including histological, molecular and functional concordance with parental tumors, are incorporated to enhance reproducibility and translational relevance. This standard aims to harmonize methodologies, improve cross-study comparability, and accelerate the clinical implementation of breast cancer organoid-based precision medicine.

The coexistence of autoimmune pancreatitis and pancreatic adenocarcinoma represents a rare but clinically significant diagnostic dilemma. Elevated IgG4 levels and imaging features suggestive of autoimmune pancreatitis may mask an underlying malignancy, leading to potential delays in definitive diagnosis and treatment. This overlap highlights the limitations of relying solely on clinical, serologic, and radiologic findings in the absence of histopathologic confirmation. We report a case of pancreatic ductal adenocarcinoma occurring in the setting of suspected autoimmune pancreatitis (AIP), highlighting the diagnostic challenge of overlapping imaging and biochemical features and the potential coexistence of both entities. A 51-year-old patient presented with progressive jaundice and unintentional weight loss. Laboratory evaluation revealed cholestasis, elevated tumor markers including CA 19-9, and markedly increased serum IgG4 levels (340 mg/dL; reference range 4.8-105 mg/dL). Contrast-enhanced computed tomography revealed a diffusely enlarged, sausage-shaped pancreas, associated with a focal hypoattenuating lesion in the uncinate process, regional lymphadenopathy, and peritoneal nodularity with ascites. Assessment of the pancreatic ductal system using gadolinium-enhanced MRI and MRCP demonstrated irregular narrowing of the main pancreatic duct without significant upstream dilatation. Histopathologic examination confirmed pancreatic ductal adenocarcinoma. This case emphasizes that pancreatic malignancy may coexist with AIP, and should not be excluded despite characteristic imaging and biochemical findings.

Sclerosing peritonitis is uncommon and often arises as sequala of inflammation and may be asymptomatic or present with variable gastrointestinal symptoms. This case describes a 41-year-old female with decompensated alcoholic cirrhosis and refractory ascites who developed recurrent spontaneous bacterial peritonitis. Months later, she presented with failure to drain ascites on repeated paracentesis. Loculations and echogenic debris were visualized on abdominal ultrasound and percutaneous removal was performed revealing a 40 cm long pale white cord. Histopathologic analysis indicated features of sclerosing peritonitis without evidence of malignancy. This case demonstrates the unusual presentation, diagnosis, and treatment of sclerosing peritonitis, which only came to clinical attention when it impeded paracentesis in a patient with contraindications to other management options. Removal of this sclerotic tissue restored the ability to perform successful large-volume paracentesis for her refractory ascites.

Dedifferentiated liposarcoma (DDLPS) is a high-grade soft tissue sarcoma predominantly arising in the retroperitoneum, characterized by an insidious clinical course. This study reports a 63-year-old female patient who presented with abdominal distension and decreased appetite, without other systemic complaints. Malignant tumor cells were identified in both ascitic smears and cell blocks. Combined with immunohistochemical (IHC) staining, the findings were consistent with sarcoma cells. Fluorescence in situ hybridization (FISH) analysis of the tissue biopsy revealed clustered amplification of mouse double minute 2 homolog (MDM2) gene. Based on the combined results of IHC and FISH testing, the final pathological diagnosis of the tissue biopsy was DDLPS. To the best of existing knowledge, this is one of the few reported cases of DDLPS initially manifesting with malignant cells detected in peritoneal fluid. This case highlights the diagnostic challenge of rare sarcomas presenting with serosal effusions and emphasizes the importance of integrating cytopathological, radiological, and molecular testing for accurate diagnosis and optimal management. Preventing misdiagnosis of this tumor as other histological subtypes is of great clinical significance, while IHC features and FISH can provide important clues for its accurate diagnosis.

Retroviral replicating vectors (RRVs) hold promise for cancer gene therapy but face limitations due to their relatively low titers and susceptibility to inactivation by body fluids, limiting their application to intratumoral delivery. To overcome these challenges and target metastatic cancers, we investigated the use of tumor-homing mesenchymal stem cells (MSCs) as RRV carriers in a clinically relevant model of malignant peritoneal mesothelioma. MSCs derived from adipose tissue, bone marrow, and umbilical cord demonstrated significant migration toward mesothelioma cells and were permissive to RRV infection and production. MSCs transferred RRVs to tumor cells more effectively in direct co-culture than in Transwell assays. Using peritoneally disseminated cancer models, we confirmed that MSCs enhanced RRV transfer, even under ascites-mimicking conditions. In vivo biomolecular imaging and flow cytometry revealed markedly reduced RRV transduction under ascites conditions; however, MSC/RRV delivery significantly enhanced intratumoral viral transmission. Furthermore, while both direct RRV and MSC/RRV treatments were effective in non-ascites models, MSC/RRV delivery achieved superior antitumor efficacy in ascites-mimicking models, resulting in robust tumor suppression and prolonged survival. These findings highlight the potential of MSCs to overcome the limitations of RRV and suggest that MSC-based RRV-mediated suicide gene therapy represents a promising strategy for peritoneally disseminated cancers complicated by cancerous ascites.

Introduction Additional immunocytochemical staining is frequently required in routine cytodiagnosis to refine presumptive diagnoses. However, optimal conditions for preserving antigenicity in cytological specimens over time remain unclear. This study evaluated the effects of preparation method, storage temperature, and storage duration on antigen preservation in clinical cytology specimens and cultured malignant tumor cells. Methods Residual sediments from 12 pleural or ascitic fluid cytology specimens were fixed in BD CytoRich Red for 1 h and processed using the SurePath liquid-based cytology method. Immunocytochemical staining performed immediately after preparation served as the baseline control. Specimens were stored as glass smears or in preservative fluid at 4 °C or -20 °C for 1 week, 1 month, or 3 months. Ki-67 and calretinin were used as primary antibodies. To reflect routine cytology practice, Papanicolaou-stained preparations were also included. Cultured malignant tumor cell lines (TCC-Meso-1, MCF-7, and KATO III) were prepared as Papanicolaou-stained, coverslipped slides and stored at room temperature. Results In clinical glass smears, neither Ki-67 nor calretinin showed a significant decline compared with baseline across storage conditions. In preservative fluid, Ki-67 positivity differed from glass smears and was associated with storage temperature; 4 °C storage resulted in significant reductions from 1 week onward. At -20 °C, reductions were limited, although selected short-term comparisons with baseline reached statistical significance. In clinical Papanicolaou-stained preparations, Ki-67 showed a significant time-dependent decrease evident at 3 months, with a similar pattern observed for calretinin. In FDR-adjusted comparisons with the non-stored baseline, Pap-stained samples exhibited the greatest reductions in rate ratios, whereas most cooled non-Pap preparations retained relatively preserved immunopositivity. In cultured Pap-stained cell preparations, Ki-67 reductions were modest and tumor type-related, with no decrease observed in TCC-Meso-1 cells. Conclusion Fixation followed by glass smear preparation and low-temperature storage (4 °C or -20 °C) allows relatively stable preservation of Ki-67 and calretinin immunoreactivity. Storage at -20 °C may be preferable when longer preservation periods are required. In contrast, delayed immunocytochemical staining of Papanicolaou-stained specimens may result in tumor type-related variability in Ki-67 immunoreactivity and therefore should be interpreted with caution.

Pseudomyxoma peritonei (PMP) is a rare peritoneal surface malignancy, most often of appendiceal origin. Diagnosis may be delayed when symptoms are indolent or when ascitic fluid studies suggest infection. A 65-year-old man presented with 1 year of progressive abdominal distension and 15 days of epigastric pain. He was haemodynamically stable and afebrile. Paracentesis showed cloudy exudative ascites with marked neutrophilia (17 900 cells/mm[3]; 52% neutrophils). Culture grew Escherichia coli and cytology was negative. Portal venous phase CT demonstrated complex hyperattenuating ascites, diffuse peritoneal implants with bulky omental caking, visceral scalloping and an abnormal enhancing appendix. Ultrasound-guided omental core biopsies confirmed high-grade mucinous carcinoma peritonei without signet-ring cells, supporting an appendiceal-type primary. The patient declined surgical exploration and died shortly after readmission with bowel perforation and abscess. This case underscores that characteristic CT findings should prompt tissue confirmation and explicit tumour grading even when ascites appears infectious.

A 62-year-old male presented with a 9-month history of intermittent epigastric distension and pain, accompanied by acid reflux, nausea, vomiting, melena, and weight loss. Physical examination revealed epigastric tenderness. Laboratory tests showed hemoglobin of 94.0 g/L and serum albumin of 22.55 g/L. Gastroscopy identified gastric cancer in the antrum with gastric retention. Pathological biopsy of the antrum confirmed poorly differentiated adenocarcinoma. Colonoscopy revealed multiple small colonic polyps (maximum diameter 5 mm). Contrast-enhanced computed tomography (CT) of the upper abdomen demonstrated an approximately 6 cm lesion in the gastric antrum and a mesenchymal malignant tumor measuring approximately 10 cm in diameter in the left hepatorenal space, along with ascites in the abdominal and pelvic cavities. The patient received preoperative nutritional support, which improved his anemia, hypoalbuminemia, and overall physical condition. Under general anesthesia, he underwent distal gastrectomy with D2 lymph node dissection and Billroth II reconstruction, combined with resection of the retroperitoneal tumor. Postoperative pathology confirmed the gastric lesion as an ulcerative poorly differentiated adenocarcinoma and the retroperitoneal tumor as a pleomorphic liposarcoma (PLPS). The patient recovered well and was discharged. For the gastric cancer, he received 6 cycles of adjuvant chemotherapy with the SOX regimen (Oxaliplatin plus S-1). Follow-up examinations, including gastroscopy and contrast-enhanced CT of the upper abdomen, were performed at 3, 6, 12, 18, 24, 30, 36, 42, and 48 months postoperatively. No evidence of tumor recurrence was detected during this follow-up period. This paper reports a concurrent case of gastric cancer and PLPS, detailing the case characteristics, diagnostic and therapeutic procedures, and postoperative follow-up. The purpose of this study is to analyze the features of this Multiple primary malignant neoplasms (MPMN) case and provide a reference for selecting appropriate clinical treatments to improve patient prognosis.

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors arising from neuroendocrine cells with malignant potential. NENs of the colorectum are uncommon, and colonic neuroendocrine neoplasms (CNENs) are particularly rare. Here, we report the diagnostic and therapeutic course of a man in his 25-year-old with small-cell neuroendocrine carcinoma (SCNEC) of the descending colon. The patient presented with sudden, severe abdominal pain accompanied by nausea and vomiting. Computed tomography (CT) revealed circumferential wall thickening of the descending colon, blurring of the surrounding fat planes, and multiple small regional lymph nodes; contrast-enhanced CT demonstrated marked, homogeneous, and persistent enhancement. The initial imaging findings were easily confounded with inflammatory disease, and the patient declined further evaluation and was discharged. Nine months later, he was readmitted because of progressive intestinal obstruction. Imaging showed substantial progression of the lesion with extension to the sigmoid colon, accompanied by signs of extra-serosal invasion and peritoneal dissemination. Colonoscopy and histopathology confirmed SCNEC. The patient received ascites control, etoposide plus cisplatin chemotherapy, and supportive care, but the response was poor. This combination of young age and tumor location in the descending colon appears to be uncommon in the existing literature. The case is further distinguished by the presence of circumferential colonic wall thickening on imaging, a feature absent in prior reports. This case highlights that colonic SCNEC in young patients may present with atypical imaging features. Colonic NENs should be included in the differential diagnosis, and early endoscopic biopsy should be performed; definitive diagnosis relies on histopathology and immunohistochemistry to facilitate early recognition and standardized management.