Clinical impact of high-quality testing for peritoneal lavage cytology in pancreatic cancer.

In pancreatic ductal adenocarcinoma (PDAC) patients, the importance of peritoneal lavage cytology, which indicates unresectability, remains controversial. This study sought to determine whether positive peritoneal lavage cytology (CY+) precludes pancreatectomy. Furthermore, we propose a novel liquid biopsy using peritoneal lavage fluid to detect viable peritoneal tumor cells (v-PTCs) with TelomeScan F35, a telomerase-specific replication-selective adenovirus engineered to express green fluorescent protein. Resectable cytologically or histologically proven PDAC patients (n = 53) were enrolled. CY was conducted immediately following laparotomy. The resulting fluid was examined by conventional cytology (conv-CY; Papanicolaou staining and MOC-31 immunostaining) and by the novel technique (Telo-CY; using TelomeScan F35). Of them, 5 and 12 were conv-CY+ and Telo-CY+, respectively. All underwent pancreatectomy. The two double-CY+ (conv-CY+ and Telo-CY+) patients showed early peritoneal recurrence (P-rec) postoperatively, despite adjuvant chemotherapy. None of the three conv-CY+ Telo-CY- patients exhibited P-rec. Six of the 10 Telo-CY+ conv-CY- patients (60%) relapsed with P-rec. Of the remaining 38 double-CY- [conv-CY-, Telo-CY-, conv-CY± (Class III)] patients, 3 (8.3%) exhibited P-rec. Although conv-CY+ status predicted poor prognosis and a higher risk of P-rec, Telo-CY was more sensitive for detecting v-PTC. Staging laparoscopy and performing conv-CY and Telo-CY are needed to confirm the indication for pancreatectomy.

Single-incision laparoscopic surgery for benign multicystic mesothelioma of the peritoneum in a young man: A case report.

Benign multicystic peritoneal mesothelioma (BMPM) is a rare condition, particularly in men, and the preoperative diagnosis poses a challenge. Here, we present a case involving single-incision laparoscopic surgery (SILS) for BMPM in a 24-year-old man with a pelvic mass and a history of ulcerative colitis. Pelvic imaging revealed multifocal cysts, prompting the performance of SILS. The tumor was successfully resected with no residual lesions, and pathology confirmed the diagnosis of BMPM. This case represents the first documented instance of SILS being employed for BMPM in a man. BMPM, characterized by pelvic multifocal cysts, is a differential diagnosis, and SILS emerges as a viable option for both diagnosis and treatment.

Malignant Extrarenal Rhabdoid tumor derived from the greater omentum: A case report and literature review.

BACKGROUND: Malignant extrarenal rhabdoid tumor (MERT) is a rare and highly metastatic tumor, which is more than 75% of patients dying within 6 months of initial diagnosis, and it often leads to misdiagnosis and delayed treatment. CASE: This paper reports a 16-year-old girl who presented with the chief complaint of acute abdominal pain. She underwent laparoscopic exploration and excisional biopsy, then pathological examination and immunohistochemistry revealed "extrarenal malignant rhabdomyoma." One month after operation, she died of intra-abdominal hemorrhage and multiple organ dysfunction. CONCLUSION: MERT were often misdiagnosed and had a poor prognosis. The surgery and chemotherapy are usually beneficial to prolong the survival time of patients with MERT.

Primary omental smooth muscle tumor in an adult male: a diagnostic dilemma for leiomyoma: a case report.

BACKGROUND: The greater omentum comprises peritoneal, adipose, vascular, and lymphoid tissues. Most omental malignancies are metastatic tumors, and the incidence of primary tumors is rare. We report on a prior omental smooth muscle tumor case in an adult male patient. CASE PRESENTATION: A 54-year-old Japanese male patient with no relevant medical history was diagnosed with an abdominal mass during a routine medical checkup. Subsequent contrast-enhanced computed tomography revealed a mass of approximately 3 cm in size in the greater omentum, and a laparotomy was performed. A 27 × 25 × 20 mm raised lesion was found in the omentum. Microscopically, spindle cells were observed and arranged in whorls and fascicles. Individual tumor cells had short spindle-shaped nuclei with slightly increased chromatin and were characterized by a slightly eosinophilic, spindle-shaped cytoplasm. The mitotic count was less than 1 per 50 high-power fields. The tumor cells showed positive immunoreactivity for α smooth muscle actin, HHF35, and desmin on immunohistochemical examination. The Ki-67 labeling index using the average method was 1.76% (261/14806). No immunoreactivity was observed for any of the other tested markers. We considered leiomyoma owing to a lack of malignant findings. However, primary omental leiomyoma has rarely been reported, and it can be difficult to completely rule out the malignant potential of smooth muscle tumors in soft tissues. Our patient was decisively diagnosed with a primary omental smooth muscle tumor considering leiomyoma. Consequently, the patient did not undergo additional adjuvant therapy and was followed up. The patient was satisfied with treatment and showed neither recurrence nor metastasis at the 13-month postoperative follow-up. DISCUSSION AND CONCLUSION: We encountered a primary smooth muscle tumor of the greater omentum with no histological findings suggestive of malignancy in an adult male patient. However, omental smooth muscle tumors are extremely difficult to define as benign, requiring careful diagnosis. Further case reports with long-term follow-up and case series are required to determine whether a true omental benign smooth muscle tumor (leiomyoma) exists. In addition, proper interpretation of the Ki-67 labeling index should be established. This case study is a foundation for future research.

Incidental finding of Psuedomyxoma Peritonei in Malignant Peripheral Nerve Sheath Tumour.

Psuedomyxoma peritonei is an infrequent clinical entity characterised by intraperitoneal mucinous/gelatinous ascites produced by the cancerous cells. It has been associated with gastrointestinal, gynaecological, lung and breast tumours. It is commonly asymptomatic and is most often detected incidentally on abdominopelvic imaging or laparoscopy. Higher histological grade of the tumour shows increased metabolic activity on 18F-Fluorodeoxyglucose (FDG) positron-emission tomography (PET) computed tomography (CT). It has been rarely reported in patients with sarcoma. We hereby present an interesting case of incidentally diagnosed pseudomyxoma peritonei on 18FDG PET-CT scan of a patient with soft tissue sarcoma of peripheral nerve sheath.

Rapid Progression of Malignant Peritoneal Mesothelioma Mimicking a Postoperative Complication in a Young Woman: A Case Report.

BACKGROUND Malignant peritoneal mesothelioma is a rare disease with a poor prognosis that often presents with vague symptoms and inconclusive laboratory test results. Causes include industrial pollutants, primarily asbestos, and certain genetic mutations, such as BAP1. Due to the nonspecific symptoms, it is often incidentally diagnosed during or after other surgical procedures. CASE REPORT A 35-year-old healthy woman underwent an uncomplicated laparoscopic left salpingo-oophorectomy for a symptomatic large ovarian mature cystic teratoma. She subsequently presented with late-onset postoperative fever, leukocytosis, and multiple intra-abdominal masses. Following an exploratory laparotomy, extensive infectious disease evaluation, and multiple biopsies requiring interdisciplinary collaboration, malignant peritoneal mesothelioma was diagnosed by positive histologic staining of an omental biopsy for D2-40 and CK5/6. This first specimen was positive for BAP1, with the second, a liver biopsy, testing negative for BAP1. The tumor cell testing was also notable for mutations in NF2, MLL2, and ARID1A, and the hereditary cancer genetic testing was overall unremarkable. Her disease progressed rapidly, and she died 6 months after her initial procedure. CONCLUSIONS This case of rapidly developing malignant peritoneal mesothelioma following surgical management of an ovarian mature teratoma highlights the complexity in diagnosing a rare disease that presents with nonspecific symptoms in an otherwise young and healthy woman. The rapid disease course was likely accelerated by expansive intraperitoneal spread and multiple somatic oncogenic mutations in BAP1, NF2, MLL2, and ARID1A. Gynecologists should keep a broad differential for postoperative complications, as occult malignancies can present with symptoms that mimic postoperative complications.

Benign multicystic peritoneal mesothelioma in a sexagenerian man: an uncommon case presentation.

BACKGROUND: Multicystic mesothelial cyst is a rare, and usually benign, tumor which is rarely diagnosed preoperatively due to the poor specificity of its symptomatology. METHODS: We report the case of a 63-year-old man with multiple comorbidities (e.g. cryptogenic cirrhosis, chronic heart failure) and a history of surgical resection of a giant abdominal cyst, who complained of recurrent intermittent abdominal pain and vomiting that appeared several weeks before. Abdominal computed tomodensitometry (CT) revealed multiple diffusely localized cysts in the abdominal cavity, ranging from 30 mm to 210 mm. RESULTS: The patient underwent surgical resection of twelve intra-abdominal cysts, identified at final pathology as benign mesothelial cysts, which were probably a recurrence following the previous surgery for a single intra-abdominal cyst. Three months later, the patient recurred with development of two new intraperitoneal cysts, with an increasing volume on CT at last follow-up (18 months). Surveillance was recommended given the patient's comorbidities and the absence of symptoms. CONCLUSIONS: Surgical resection is the treatment of choice for multicystic peritoneal mesothelioma, a rare disease that should be considered more as a borderline tumor than a benign tumor, given the high risk of recurrence and possible malignant transformation.

Genomic characterization and detection of potential therapeutic targets for peritoneal mesothelioma in current practice.

Peritoneal mesothelioma (PeM) is an aggressive tumor with limited treatment options. The current study aimed to evaluate the value of next generation sequencing (NGS) of PeM samples in current practice. Foundation Medicine F1CDx NGS was performed on 20 tumor samples. This platform assesses 360 commonly somatically mutated genes in solid tumors and provides a genomic signature. Based on the detected mutations, potentially effective targeted therapies were identified. NGS was successful in 19 cases. Tumor mutational burden (TMB) was low in 10 cases, and 11 cases were microsatellite stable. In the other cases, TMB and microsatellite status could not be determined. BRCA1 associated protein 1 (BAP1) mutations were found in 32% of cases, cyclin dependent kinase inhibitor 2A/B (CDKN2A/B) and neurofibromin 2 (NF2) mutations in 16%, and ataxia-telangiectasia mutated serine/threonine kinase (ATM) in 11%. Based on mutations in the latter two genes, potential targeted therapies are available for approximately a quarter of cases (i.e., protein kinase inhibitors for three NF2 mutated tumors, and polyADP-ribose polymerase inhibitors for two ATM mutated tumors). Extensive NGS analysis of PeM samples resulted in the identification of potentially effective targeted therapies for about one in four patients. Although these therapies are currently not available for patients with PeM, ongoing developments might result in new treatment options in the future.

Diagnosis and treatment of malignant retroperitoneal mesothelioma: A case report.

RATIONALE: Malignant peritoneal mesothelioma (MPM) is a rare clinical disease. Although there are several reports describing intraperitoneal mesothelioma of the lung, liver, and intestine, retroperitoneal mesothelioma is, to our knowledge, very rare and rarely reported. In recent years, our best clinical protocols for the treatment and diagnosis of retroperitoneal mesothelioma have not been proven and the diagnosis and treatment are challenging. PATIENT CONCERNS: A 37-year-old Chinese woman complained of bilateral low back pain for a month, with obvious symptoms of low back pain on the left side. To treat low back pain, retroperitoneal masses were found during physical examination. The patient consulted a urological specialist for further treatment. DIAGNOSIS: After the operation, pathological biopsy confirmed retroperitoneal epithelioid diffuse mesothelioma. INTERVENTIONS: After exclusion of surgical contraindications, the patient underwent laparoscopic retroperitoneal lesion resection under tracheal intubation and general anesthesia, and the operation was successful. OUTCOMES: On the tenth day after surgery, the patient vital signs were stable, and he was discharged. LESSONS: Patients with malignant peritoneal mesothelioma may have no typical clinical symptoms, and the diagnosis is based on pathological and immunohistochemical examination. In selected patients, surgical cell reduction and intraoperative intraperitoneal heat chemotherapy have become the first choice of treatment, which can achieve ideal therapeutic effects and prolong survival.

[Call for attention to the value and challenge of liquid biopsy in diagnosis and treatment for peritoneal metastasis of gastric cancer].

Peritoneal metastasis is the common route of metastasis in gastric cancer and is a major cause of death in advanced gastric cancer. Early intervention with comprehensive treatment can effectively improve the prognosis of some patients with peritoneal metastasis. However, early peritoneal metastasis in gastric cancer is predominantly micro-metastasis, which cannot be effectively evaluated by imaging studies. Moreover, the detection of disseminated cancer cells in peritoneal lavage suffers from a low detection rate and significant heterogeneity. In recent years, the development and application of new liquid biopsy technologies such as circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) have provided new means to assess potential peritoneal metastasis at the cellular and molecular levels, gradually becoming research hotspots in this field. This review will summarize the relevant progress of liquid biopsy in peritoneal metastasis, which holds significant importance for improving the prognosis of gastric cancer patients in China.

Ruptured Ovarian Cystic Teratoma: A Rare Diagnosis, Easily to Be Confused with Peritoneal Carcinomatosis.

Although ovarian cystic teratoma is the most common ovarian tumor, complications are quite rare. However, it is important to be recognized by the radiologist in order to avoid inaccurately diagnosing them as malignant lesions. This case report describes a 61-year-old postmenopausal woman, who presented to the emergency room with abdominal pain following a minor blunt abdominal trauma. In this context, a CT scan was performed, which showed the presence of round, hypodense masses randomly distributed in the peritoneum, with coexisting ascites in moderate amount; ovarian carcinoma with peritoneal carcinomatosis was suspected. The patient was hospitalized and an MRI of the abdomen and pelvis was recommended for a more detailed lesion characterization. Following this examination, the patient was diagnosed with mature cystic ovarian teratoma complicated by rupture. Surgery was performed, and the outcome was favorable. The cases of ruptured cystic teratomas are rare, and to our knowledge, this is the first occurrence described in literature. Special attention must be paid when confronting with such a case in medical practice, since it can easily misdiagnosed as peritoneal carcinomatosis.

Peritoneal Tumor DNA as a Prognostic Biomarker in Gastric Cancer: A Systematic Review and Meta-Analysis.

PURPOSE: Gastric cancers commonly spread to the peritoneum. Its presence significantly alters patient prognosis and treatment-intent; however, current methods of peritoneal staging are inaccurate. Peritoneal tumor DNA (ptDNA) is tumor-derived DNA detectable in peritoneal lavage fluid. ptDNA positivity may indicate peritoneal micrometastasis and may be more sensitive than cytology in staging the peritoneum. In this meta-analysis, we evaluated the prognostic potential of ptDNA in gastric cancer. METHODS: PubMed, Embase, Scopus, and Web of Science databases were searched using PRISMA guidelines. Studies published between January 1, 1990, and April 30, 2023, containing quantitative data relating to ptDNA in gastric cancer were meta-analyzed. RESULTS: Six studies were analyzed. Of the total 757 patients with gastric adenocarcinoma, 318 (42.0%) were stage I, 311 (41.0%) were stage II/III, 116 (15.3%) were stage IV, and 22 (2.9%) were undetermined. Overall, ptDNA detected cytology-positive cases with a sensitivity and specificity of 85.2% (95% CI, 66.5 to 100.0) and 91.5% (95% CI, 86.5 to 96.6), respectively. Additionally, ptDNA was detected in 54 (8.5%) of 634 cytology-negative patients. The presence of ptDNA negatively correlated with pathological stage I (relative risk [RR], 0.29 [95% CI, 0.13 to 0.66]) and positively correlated with pathological stage IV (RR, 8.61 [95% CI, 1.86 to 39.89]) disease. Importantly, ptDNA positivity predicted an increased risk of peritoneal-specific metastasis (RR, 13.81 [95% CI, 8.11 to 23.53]) and reduced 3-year progression-free (RR, 5.37 [95% CI, 1.39 to 20.74]) and overall (hazard ratio, 4.13 [95% CI, 1.51 to 11.32]) survival. CONCLUSION: ptDNA carries valuable prognostic information and can detect peritoneal micrometastases in patients with gastric cancer. Its clinical utility in peritoneal staging for gastric cancer deserves further investigation.

Utility of Circulating Tumor DNA Assessment in Characterizing Recurrence Sites after Optimal Resection for Metastatic Colorectal Cancer.

BACKGROUND: Plasma circulating tumor DNA (ctDNA) is a promising biomarker for metastatic colorectal cancer (mCRC); however, its role in characterizing recurrence sites after mCRC resection remains poorly understood. This single-institution study investigated the timing of ctDNA detection and its levels in the context of recurrence at different sites after mCRC resection. STUDY DESIGN: Patients who underwent optimal resection of CRC metastases involving the peritoneum, distant lymph nodes, or liver, with serial postoperative tumor-informed ctDNA assessments (Signatera) were included. Recurrence sites, as defined by surveillance imaging or laparoscopy, were categorized as peritoneal-only and other distant sites (liver, lung, lymph nodes, or body wall). RESULTS: Among the 31 included patients, ctDNA was detected in all 26 (83.4%) patients with postoperative recurrence and was persistently undetectable in 5 patients who did not experience recurrence. At 3 months postsurgery, ctDNA was detected in 2 (25%) of 8 patients with peritoneal-only recurrence and 17 (94.4%) of 18 patients with distant recurrence (p < 0.001). Beyond 3 months, ctDNA was detected in the remaining 6 patients with peritoneal-only disease and 1 patient with distant disease. ctDNA detection preceded the clinical diagnosis of recurrence by a median of 9 weeks in both groups. At recurrence, peritoneal-only recurrent cases exhibited lower ctDNA levels (median 0.4 mean tumor molecules/mL, interquartile range 0.1 to 0.8) compared with distant recurrence (median 5.5 mean tumor molecules/mL, interquartile range 0.8 to 33.3, p = 0.004). CONCLUSIONS: Peritoneal-only recurrence was associated with delayed ctDNA detection and low levels of ctDNA after optimal resection for mCRC. ctDNA testing may effectively characterize recurrence sites and may help guide subsequent treatments specific to the disease sites involved.

Nanomechanical Analysis of Living Small Extracellular Vesicles to Identify Gastric Cancer Cell Malignancy Based on a Biomimetic Peritoneum.

Gastric cancer is one of the most prevalent digestive malignancies. The lack of effective in vitro peritoneal models has hindered the exploration of the potential mechanisms behind gastric cancer's peritoneal metastasis. An accumulating body of research indicates that small extracellular vesicles (sEVs) play an indispensable role in peritoneal metastasis of gastric cancer cells. In this study, a biomimetic peritoneum was constructed. The biomimetic model is similar to real peritoneum in internal microstructure, composition, and primary function, and it enables the recurrence of peritoneal metastasis process in vitro. Based on this model, the association between the mechanical properties of sEVs and the invasiveness of gastric cancer was identified. By performing nanomechanical analysis on sEVs, we found that the Young's modulus of sEVs can be utilized to differentiate between malignant clinical samples (ascites) and nonmalignant clinical samples (peritoneal lavage). Furthermore, patients' ascites-derived sEVs were verified to stimulate the mesothelial-to-mesenchymal transition, thereby promoting peritoneal metastasis. In summary, nanomechanical analysis of living sEVs could be utilized for the noninvasive diagnosis of malignant degree and peritoneal metastasis of gastric cancer. This finding is expected to contribute future treatments.