^(18)F-FDG PET/CT findings of paratesticular alveolar rhabdomyosarcoma

Rhabdomyosarcoma(RMS)originates from primitive mesenchymal cells and is the most common soft tissue tumor in childhood.^(18)F-fluoro-deoxyglucose(^(18)F-FDG)positron emission tomography(PET)/computed tomography(CT)has been reported to be valuable in RMS staging and risk stratification.Paratesticular RMS is a relatively uncommon form of RMS,most of which are of the embryonal histologic type.Paratesticular alveolar RMS is associated with aggressive behavior,high metastatic potential,and poor outcomes.To the best of our knowledge,^(18)F-FDG PET/CT imaging findings of paratesticular alveolar RMS have never been described.Here,we report on a 16-year-old boy's rare paratesticular alveolar RMS with multiple metastases and its findings on^(18)F-FDG PET/CT.This case also demonstrates the potential value of^(18)F-FDG PET/CT in RMS staging and treatment decisions,and may aid in the differential diagnosis.

Pulmonary alveolar proteinosis induced by X-linked agammaglobulinemia:A case report

BACKGROUND Pulmonary alveolar proteinosis(PAP)and X-linked agammaglobulinemia(XLA)are rare diseases in children.Many theories infer that immunodeficiency can induce PAP,but these reports are almost all review articles,and there is little clinical evidence.We report the case of a child with both PAP and XLA.CASE SUMMARY A 4-month-old boy sought medical treatment due to coughing and difficulty in breathing for>2 wk.He had been hospitalized multiple times due to respiratory infections and diarrhea.Chest computed tomography and alveolar lavage fluid showed typical PAP-related manifestations.Genetic testing confirmed that the boy also had XLA.Following total lung alveolar lavage and intravenous immunoglobulin replacement therapy,the boy recovered and was discharged.During the follow-up period,the number of respiratory infections was significantly reduced,and PAP did not recur.CONCLUSION XLA can induce PAP and improving immune function contributes to the prognosis of children with this type of PAP.

Rhabdomyosarcoma in Children: About 10 Cases

Introduction: Rhabdomyosarcoma (RMS) is a malignant soft-tissue tumor arising from striated muscle cells. It accounts for 60% - 70% of malignant mesenchymal tumors and 5% of pediatric cancers. Two-thirds of these cancers are diagnosed in children under 6 years of age, with a slight male predominance. Materials and Methods: This is a retrospective descriptive study of 10 cases of RMS collected in the pediatric hematology and oncology department of the Oujda university hospital, over a 5-year period, running from January 2018 to December 2022. Results: The median age at diagnosis was 3 years, with a sex ratio of 1. The mean time to diagnosis was 2 months. The most common site was the head and neck (50%), followed by the genitourinary tract (20%), the extremities (20%) and finally the abdomen (10%). The most frequent mode of discovery was a mass or swelling found in 90% of patients (all sites included), followed by exophthalmos in 30% of cases. At the diagnostic stage, CT scans were performed in 70% of cases and MRI in 5 patients (50%). Histological diagnosis was determined by immunohistochemical pathology in all our patients, with a predominance of embryonal (70%) versus alveolar (20%) and spindle cell types (10%). All patients underwent an extension workup, and a cervico-thoraco-abdominopelvic CT was performed in all patients (100%);MRI was performed in 2 patients (20%);lymph node involvement was present in 5 patients (50%). Metastases at the time of diagnosis were noted in only 1 patient (10%), who simultaneously presented with two metastatic sites;testicular and abdominal wall. Sixty percent of patients presented with advanced disease (high risk) and 40% with standard risk. Chemotherapy was used in all patients (100%), with upfront tumor resection performed in 40%. Fifty percent of patients received radiotherapy at a mean dose of 43 Gy, with the orbit the most frequently irradiated area (30%). All patients underwent CTscan and/or MRI and/or ultrasound surveillance. Follow-up during and after treatment was marked by complete remission in 8patients, loss of sight in one patient, and one patient died as a result of progressive disease. Conclusion: RMS is a malignant tumor of striated muscle. The epidemiological and clinical features of this tumor in our study are generally similar to those described in the literature. Management of these tumors requires multidisciplinary collaboration involving oncopediatric, radiologist, pediatric surgeon, pathologist and radiotherapist.

Clinical approach for pulmonary alveolar proteinosis in children

In this editorial,we discuss the clinical implications of the article by Zhang et al.Pulmonary alveolar proteinosis(PAP)is a rare lung disease characterized by excessive surfactant accumulation in the alveoli.It is classified into four categories:Primary,secondary,congenital,and unclassified forms.Primary PAP is caused by the disruption of granulocyte-macrophage colony-stimulating factor(GM-CSF)receptor signaling,which is necessary for the clearance of surfactant by alveolar macrophages.It is further divided into autoimmune PAP,caused by anti-GM-CSF antibodies blocking alveolar macrophage activation,and hereditary PAP,resulting from mutations in genes encoding GM-CSF receptors.Secondary PAP develops due to conditions affecting the number or function of alveolar macrophages,such as infections,immunodeficiency,hematological disorders,or exposure to inhaled toxins.Congenital PAP is linked to mutations in genes involved in surfactant protein production.Notably,the causes of PAP differ between children and adults.Diagnostic features include a characteristic"crazypaving"pattern on high-resolution computed tomography,accompanied by diffuse ground-glass opacities and interlobular septal thickening.The presence of PAP can be identified by the milky appearance of bronchoalveolar lavage fluid and histological evaluation.However,these methods cannot definitively determine the cause of PAP.Whole lung lavage remains the standard treatment,often combined with specific therapies based on the underlying cause.

Pleomorphic rhabdomyosarcoma of the vagina: A case report

BACKGROUND Rhabdomyosarcoma(RMS)of the vagina in postmenopausal women is an extre-mely rare malignant tumor that was originally described as a unique group of soft tissue sarcomas originating from primitive mesenchymal cells.It was first re-ported in postmenopausal women in 1970,and fewer than 50 postmenopausal patients have been reported to date.CASE SUMMARY A 68-year-old multiparous female was admitted to the hospital on October 11,2023,with the chief complaint of a mass causing vaginal prolapse with incomplete urination that had persisted for 4 months.The vaginal mass was approximately the size of a pigeon egg;after lying down,the vaginal mass retracted.Complete resection was performed,and vaginal pleomorphic RMS was diagnosed based on pathology and immunohistochemical staining features.The patient is currently undergoing chemotherapy.The present study also reviewed the clinical,histolo-gical,and immunohistochemical features and latest treatment recommendations for vaginal RMS.Any abnormal vaginal mass should be promptly investigated through pelvic examination and appropriate imaging.The current initial treat-ment for vaginal RMS is biopsy and primary chemotherapy.CONCLUSION When surgery is planned for vaginal RMS,an organ-preserving approach should be considered.

Adult rhabdomyosarcoma combined with acute myeloid leukemia: A case report

BACKGROUND Rhabdomyosarcoma is a tumor of mesenchymal origin.Secondary leukemia is a complication of previous transformation to other hematologic disorders or is a treatment-related acute myeloid leukemia secondary to cytotoxic chemotherapy or radiation therapy for other malignancies.CASE SUMMARY We present the case of a 36-year-old female patient who was diagnosed with rhabdomyosarcoma and acute myeloid leukemia.Further disease progression was observed after multiline chemotherapy.Eventually,the patient suffered cerebral hemorrhage,which resulted in death.CONCLUSION The incidence of rhabdomyosarcoma in adults is extremely low,and secondary leukemia caused by rhabdomyosarcoma is even rarer.Secondary leukemia has a very poor prognosis and a low overall survival rate.

Two-stage extraction by partial grinding of impacted mandibular third molar in close proximity to the inferior alveolar nerve

BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third molar(IMM3)near the IAN to prevent IAN injury during IMM3 extraction.METHODS Between January 1996 and March 2022,25 patients with IMM3 roots near the IAN were enrolled.The first stage of the operation consisted of grinding a major part of the IMM3 crown with a high-speed turbine dental drill to achieve sufficient space between the mandibular second molar and IMM3.After 6 months,when the root tips were observed to be away from the IAN on X-ray examination,the remaining part of the IMM3 was completely removed.RESULTS All IMM3s were extracted easily without symptoms of IAN injury after extraction.CONCLUSION Partial IMM3 grinding may be a good alternative treatment option to avoid IAN injury in high-risk cases.

Fifty-five cases of hepatic alveolar echinococcosis combined with lymph node metastasis:A retrospective study

BACKGROUND Lymph node metastasis is a specific type of metastasis in hepatic alveolar echinococcosis(AE).Currently,there is a scarcity of describing the clinical characteristics and lymph node metastasis rules of patients with hepatic AE combined with lymph node metastasis and its mechanism and management are still controversial.Radical hepatectomy combined with regional lymph node dissection is a better treatment.AIM To analyse the clinical features of hepatic AE combined with lymph node metastasis to explore its treatment and efficacy.METHODS A total of 623 patients with hepatic AE admitted to the First Affiliated Hospital of Xinjiang Medical University from 1 January 2012 to 1 January 2022 were retrospectively analysed.Fifty-five patients with combined lymph node metastasis were analysed for their clinical data,diagnosis and treatment methods,follow-up efficacy,and characteristics of lymph node metastasis.Finally,we comparatively analysed the lymph node metastasis rates at different sites.Categorical variables are expressed as frequencies and percentages,and the analysis of difference was performed using theχ2 test.The Bonferroni method was used for pairwise comparisons when statistical differences existed between multiple categorical variables.RESULTS A lymph node metastasis rate of 8.8%(55/623)was reported in patients with hepatic AE,with a female predilection(69.1%)and a statistically significant sex difference(χ2=8.018,P=0.005).Of the 55 patients with lymph node metastasis,72.7%had a parasite lesion,neighbouring organ invasion,and metastasis stage of P3N1M0 and above,of which 67.3%,78.2%,and 34.5%of hepatic AE lesions invaded the bile ducts,blood vessels,and distant metastases,respectively.Detection rates of lymph node metastasis of 16.4%,21.7%,and 34.2%were reported for a preoperative abdominal ultrasound,magnetic resonance imaging,and computed tomography examinations.All patients were intraoperatively suspected with enlarged lymph nodes and underwent radical hepatectomy combined with regional lymph node dissection.After surgery,a routine pathological examination was conducted on the resected lymph nodes.A total of 106 positive lymph nodes were detected in six groups at various sites,including 51 single-group metastasis cases and four multi-group metastasis cases.When the metastasis rates at different sites were statistically analysed,we observed that the metastasis rate in the para-hepatoduodenal ligament lymph nodes was significantly higher than that of the other sites(χ^(2)=128.089,P=0.000<0.05).No statistical difference was observed in the metastasis rate between the five other groups.Clavien-Dindo grade IIIa complication occurred in 14 cases,which improved after administering symptomatic treatment.Additionally,lymph node dissection-related complications were not observed.Recurrence after 2 years was observed in one patient.CONCLUSION Lymph node metastasis is a rare form of metastasis in hepatic AE,which is more frequent in women.Parahepatoduodenal ligament lymph nodes are commonly observed.Radical hepatectomy combined with regional lymph node dissection is a safe,effective,and feasible treatment for liver AE combined with lymph node metastasis.

Coinfection with hepatic cystic and alveolar echinococcosis with abdominal wall abscess and sinus tract formation:A case report

BACKGROUND Hepatic cystic and alveolar echinococcosis coinfections,particularly with concurrent abscesses and sinus tract formation,are extremely rare.This article presents a case of a patient diagnosed with this unique presentation,discussing the typical imaging manifestations of both echinococcosis types and detailing the diagnosis and surgical treatment experience thereof.CASE SUMMARY A 39-year-old Tibetan woman presented with concurrent hepatic cystic and alveolar echinococcosis,accompanied by abdominal wall abscesses and sinus tract formation.Initial conventional imaging examinations suggested only hepatic cystic echinococcosis,but intraoperative and postoperative pathological examination revealed the coinfection.Following radical resection of the lesions,the patient’s condition improved,and she was discharged soon thereafter.Subsequent outpatient follow-ups confirmed no recurrence of the hydatid lesion and normal surgical wound healing.Though mixed hepatic cystic and alveolar echinococcosis with abdominal wall abscesses and sinus tract formations are rare,the general treatment approach remains consistent with that of simpler infections of alveolar echinococcosis.CONCLUSION Lesions involving the abdominal wall and sinus tract formation,may require radical resection.Long-term prognosis includes albendazole and follow-up examinations.

Characteristics of the imaging diagnosis of alveolar echinococcosis

Alveolar echinococcosis(AE)primarily manifests in the liver and exhibits charac-teristics resembling those of slow-growing malignant tumours.Untreated Echino-coccus multilocularis infection can be lethal.By infiltrating the vascular systems,biliary tracts,and the hilum of the liver,it might lead to various problems.Due to its ability to infiltrate neighbouring tissues or metastasize to distant organs,AE can often be mistaken for malignancies.We present a concise overview of the epi-demiological and pathophysiological characteristics of AE,as well as the clinical manifestations of the disease.This article primarily examines the imaging charac-teristics of AE using various imaging techniques such as ultrasonography,com-puted tomography(CT),magnetic resonance imaging,diffusion-weighted ima-ging,and virtual non-enhanced dual-energy CT.We additionally examined the contribution of radiography in the diagnosis,treatment,and monitoring of the condition.

Alveolar Rhabdomyosarcoma of the Laryngohypopharynx： A Case Report

Introduction Rhabdomyosarcoma is one of the most commonly seen soft-tissue sarcomas in children and teenagers, approximately accounting for half of all soft-tissue sarcomas. The tumor is usually found in head and neck, four limbs and urogenital system. However, the tumor orig- inating from the laryngohypopharynx is rare. In 2008, a patient with alveolar rhabdomyosarcoma of the laryngohypopharynx was admitted to our hospital. Clinical information of the disease was reported as follows, and clinicopathologic features and current therapeutic principle were discussed and summarized in combination with the review of literature, to facilitate the diagnosis and treatment of the patients with rhabdomyosarcoma of the laryngohypopharynx in future.

Effect and mechanism of reactive oxygen species-mediated NOD-like receptor family pyrin domain-containing 3 inflammasome activation in hepatic alveolar echinococcosis

BACKGROUND The NOD-like receptor family pyrin domain-containing 3(NLRP3)inflammasome is a significant component of the innate immune system that plays a vital role in the development of various parasitic diseases.However,its role in hepatic alveolar echinococcosis(HAE)remains unclear.AIM To investigate the NLRP3 inflammasome and its mechanism of activation in HAE.METHODS We assessed the expression of NLRP3,caspase-1,interleukin(IL)-1β,and IL-18 in the marginal zone and corresponding normal liver of 60 patients with HAE.A rat model of HAE was employed to investigate the role of the NLRP3 inflammasome in the marginal zone of HAE.Transwell experiments were conducted to investigate the effect of Echinococcus multilocularis(E.multilocularis)in stimulating Kupffer cells and hepatocytes.Furthermore,immunohistochemistry,Western blotting,and enzyme-linked immunosorbent assay were used to evaluate NLRP3,caspase-1,IL-1β,and IL-18 expression;flow cytometry was used to detect apoptosis and reactive oxygen species(ROS).RESULTS NLRP3 inflammasome activation was significantly associated with ROS.Inhibition of ROS production decreased NLRP3-caspase-1-IL-1βpathway activation and mitigated hepatocyte damage and inflammation.CONCLUSION E.multilocularis induces hepatocyte damage and inflammation by activating the ROS-mediated NLRP3-caspase-1-IL-1βpathway in Kupffer cells,indicating that ROS may serve as a potential target for the treatment of HAE.

Mandibular Embryonal Rhabdomyosarcoma Confused with a Vascular Malformation: About a Case

Malignant mesenchymal tumors (MTM) in children represent 5% to 10% of malignant tumors in children. They constitute a heterogeneous group of tumors of various differentiations depending on their supposed tissue of origin. They mainly include tumors of muscular origin, those derived from connective, vascular, nervous, or adipose tissue. Rhabdomyosarcoma (RMS) is the most common mesenchymal tumor in children and adolescents (60% to 70% of them). And it accounts for 5.8% of all malignant solid tumors in children. Almost half of rhabdomyosarcomas occur in the head and neck. The prognosis for this type of tumor is particularly poor. A case of rhabdomyosarcoma in the mandible with extension to the abdominal wall and unilateral testis in a 6-month-old infant is reported with evolution since birth. It is a purplish lesion at the level under the right chin which was initially taken for vascular malformation, evolving very quickly towards a mandibular mass deforming the painful face with inflammatory signs, followed by the appearance of a hard swelling under the skin on the left flank taking on the same aspect of the mandibular mass. This observation illustrates the need to know how to systematically think about tumor causes in the face of atypical aspects and to carry out an anatomopathological examination.

Pneumocystis jirovecii diagnosed by next-generation sequencing of bronchoscopic alveolar lavage fluid: A case report and review of literature

BACKGROUND The advent of molecular targeted agents and immune checkpoint inhibitors has greatly improved the treatment of advanced renal cell carcinoma(RCC), thus significantly improving patient survival. The incidence of rare drug-related adverse events has gained increased attention.CASE SUMMARY We report a patient with advanced RCC treated with multiple lines of molecular targeted agents and immune checkpoint inhibitors, who developed a pulmonary infection after treatment with everolimus in combination with lenvatinib. Determining the pathogenic organism was difficult, but it was eventually identified as Pneumocystis jirovecii by next-generation sequencing(NGS) of bronchoscopic alveolar lavage fluid(BALF) and successfully treated with trimethoprim-sulfamethoxazole.CONCLUSION Rare pulmonary infections caused by molecular targeted agents are not uncommon in clinical practice, but their diagnosis is difficult. Evaluating BALF with NGS is a good method for rapid diagnosis of such infections.

Unexpected diffuse lung lesions in a patient with pulmonary alveolar proteinosis:A case report

BACKGROUND Pulmonary alveolar proteinosis(PAP)often presents nonspecifically and can be easily confused with:(1)Idiopathic interstitial lung fibrosis;(2)alveolar carcinoma;(3)pulmonary tuberculosis;and(4)other lung diseases such as viral pneumonia,mycoplasma pneumonia,and chlamydial pneumonia.CASE SUMMARY Diagnosis:In this case,a patient was diagnosed with PAP through transbronchial cryobiopsy(TBCB)and quantitative metagenomic next-generation sequencing,which confirmed the impairment of surfactant turnover as the underlying cause of PAP.Interventions:High-volume total lung lavage was performed for this patient.Outcomes:The patient's clinical condition had improved significantly by the 6-month follow-up,with a 92%finger oxygen saturation.A repeat chest computed tomography scan revealed scattered patchy ground-glass shadows in both lungs,which was consistent with alveolar protein deposition but with a lower density than in the radiograph from October 23,2022.CONCLUSION TBCB has unique advantages in diagnosing atypical alveolar protein deposition,particularly for enabling the early detection of PAP.This information can help patients take preventive measures to prevent or halt PAP development by avoiding dusty environments and seeking treatment with total lung lavage and inhaled granulocyte macrophage colony-stimulating factor.

Percutaneous management in hepatic alveolar echinococcosis:A sum of single center experiences and a brief overview of the literature

BACKGROUND Hepatic alveolar echinococcosis(HAE)is a serious zoonotic infection that affects humans.It may have a tumor-like appearance at times.Percutaneous treatment of HAE patients is extremely relaxing for them.HAE is a significant human zoonotic infection caused by the fox tapeworm Echinococcus Multilocularis larvae.It possesses the characteristics of an invasive tumor-like lesion due to its infiltrative growth pattern and protracted incubation period.The disease is endemic over central Europe,Asia,and North America.AIM To characterize HAE patients who were treated percutaneously,their outcomes,and the major technical features of percutaneous treatment in HAE.METHODS Patients who were treated with percutaneous cyst drainage and/or percutaneous biliary drainage were included in the study.Uncorrected abnormal coagulation values and solid or non-infected HAE with minor necrotic change were excluded.RESULTS Thirty-two patients underwent percutaneous cyst drainage,two patients underwent percutaneous biliary drainage,and four patients underwent percutaneous biliary drainage alone.Interventional radiology is utilized to drain echinococcal necrosis and abscesses within/without the liver,as well as diseased and clogged bile ducts.CONCLUSION Percutaneous drainage of cyst contents and/or biliary channels using a minimally invasive technique is a very beneficial.Percutaneous cyst drainage with albendazole therapy improves quality of life in patients who are unable to undergo surgery,even when the mass resolves with long-term treatment.

Sclerostin antibody improves alveolar bone quality in the Hyp mouse model of X-linked hypophosphatemia

X-linked hypophosphatemia (XLH) is a rare disease of elevated fibroblast growth factor 23 (FGF23) production that leads tohypophosphatemia and impaired mineralization of bone and teeth. The clinical manifestations of XLH include a high prevalence ofdental abscesses and periodontal disease, likely driven by poorly formed structures of the dentoalveolar complex, including thealveolar bone, cementum, dentin, and periodontal ligament. Our previous studies have demonstrated that sclerostin antibody (SclAb) treatment improves phosphate homeostasis, and increases long bone mass, strength, and mineralization in the Hyp mousemodel of XLH. In the current study, we investigated whether Scl-Ab impacts the dentoalveolar structures of Hyp mice. Male andfemale wild-type and Hyp littermates were injected with 25 mg·kg−1 of vehicle or Scl-Ab twice weekly beginning at 12 weeks of ageand euthanized at 20 weeks of age. Scl-Ab increased alveolar bone mass in both male and female mice and alveolar tissue mineraldensity in the male mice. The positive effects of Scl-Ab were consistent with an increase in the fraction of active(nonphosphorylated) β-catenin, dentin matrix protein 1 (DMP1) and osteopontin stained alveolar osteocytes. Scl-Ab had no effecton the mass and mineralization of dentin, enamel, acellular or cellular cementum. There was a nonsignificant trend towardincreased periodontal ligament (PDL) attachment fraction within the Hyp mice. Additional PDL fiber structural parameters were notaffected by Scl-Ab. The current study demonstrates that Scl-Ab can improve alveolar bone in adult Hyp mice.

Minimally Invasive Maxillofacial Surgery Using Digital Work Surgery: A Case of Alveolar Ridge Reconstruction after Maxillary Cystectomy

Introduction: Iliac particulate cancellous bone and marrow (PCBM) is commonly used as a high-quality reconstruction material;however, PCBM cannot be extracted in sufficient amounts to meet demand. To determine the appropriate amount of iliac PCBM to be collected, we used digital technology to measure the volume required for jaw reconstruction before surgery. Clinical Case: The patient, a 23-year-old man, underwent surgery for a calcifying odontogenic cyst. A maxillary cyst occupied the left anterior-premolar region (tooth 21 - 25) and the deciduous canine remained;a permanent canine was included in the cyst. We planned to preserve the teeth except for the impacted canine, completely excise the maxillary cyst, and preserve the alveolar ridge morphology. Preoperative digital imaging was used to determine the amount of alveolar ridge reconstruction required and accordingly determine the amount of iliac cancellous bone to be harvested. We used a titanium mesh tray and grafts of iliac particulate cancellous bone and marrow to reconstruct the alveolar ridge. The amount of iliac cancellous bone that needed to be collected was clarified and the supply amount could be collected in just the right amount;thus, the cortical bone of the iliac inner plate could be preserved. The alveolar bone morphology was reconstructed to allow the placement of dental implants as per the preoperative digital surgery. Three years after the operation, no sign of recurrence has been observed. Conclusion: Minimally invasive surgery was performed by clarifying the amount of iliac cancellous bone graft that needs to be harvested, which improved the accuracy of surgery.

Unusual clinical presentation of oral pyogenic granuloma with severe alveolar bone loss:A case report and review of literature

BACKGROUND Pyogenic granuloma(PG)is a localized,reddish and vascularized hyperplastic lesion of the connective tissue which occurs in the oral cavity.In most cases,the presence of this lesion does not show alveolar bone resorption.The pathology is diagnosed clinically with some caution.However,the diagnosis and treatment are usually corroborated with histopathological evidence.CASE SUMMARY Three clinical cases of PG associated with bone loss were described in this study.The three patients presented tumor-like growth which bled on touch,and were associated with local irritant factors.Radiographs showed bone loss.All cases were treated with conservative surgical excision.The scarring was satisfactory,and there was no case of recurrence.The diagnoses were based on clinical findings,and were confirmed histopathologically.CONCLUSION The occurrence of oral PG with bone loss is unusual.Therefore,clinical and radiographic evaluations are important for the diagnosis.

Incidence,characteristics and risk factors for alveolar recruitment maneuver-related hypotension in patients undergoing laparoscopic colorectal cancer resection

BACKGROUND Alveolar recruitment maneuvers(ARMs)may lead to transient hypotension,but the clinical characteristics of this induced hypotension are poorly understood.We investigated the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection.AIM To investigate the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection.METHODS This was a secondary analysis of the PROtective Ventilation using Open Lung approach Or Not trial and included 140 subjects.An ARM was repeated every 30 min during intraoperative mechanical ventilation.The primary endpoint was ARM-related hypotension,defined as a mean arterial pressure(MAP)<60 mmHg during an ARM or within 5 min after an ARM.The risk factors for hypotension were identified.The peri-ARM changes in blood pressure were analyzed for the first three ARMs(ARM_(1,2,3))and the last ARM(ARMl_(ast)).RESULTS Thirty-four subjects(24.3%)developed ARM-related hypotension.Of all 1027 ARMs,37(3.61%)induced hypotension.More ARMs under nonpneumoperitoneum(33/349,9.46%)than under pneumoperitoneum conditions(4/678,0.59%)induced hypotension(P<0.01).The incidence of hypotension was higher at ARM_(1)points than at non-ARM_(1)points(18/135,13.3%vs 19/892,2.1%;P<0.01).The median percentage decrease in the MAP at ARM1 was 14%.Age≥74 years,blood loss≥150 mL and peak inspiratory pressure under pneumoperitoneum<24 cm H_(2)O were risk factors for ARM-related hypotension.CONCLUSION When the ARM was repeated intraoperatively,a quarter of subjects developed ARM-related hypotension,but only 3.61%of ARMs induced hypotension.ARM-related hypotension most occurred in a hemodynamically unstable state or a hypovolemic state,and in elderly subjects.Fortunately,ARMs that were performed under pneumoperitoneum conditions had less impact on blood pressure.