Sequential MRI Evaluation of Lymphatic Abnormalities over the Course of Fontan Completion.

Purpose To evaluate lymphatic abnormalities before and after Fontan completion using noncontrast lymphatic imaging and relate findings with postoperative outcomes. Materials and Methods This study is a retrospective review of noncontrast T2-weighted lymphatic imaging performed at The Children's Hospital of Philadelphia from June 2012 to February 2023 in patients with single ventricle physiology. All individuals with imaging at both pre-Fontan and Fontan stages were eligible. Lymphatic abnormalities were classified into four types based on severity and location of lymphatic vessels. Classifications were compared between images and related to clinical outcomes such as postoperative drainage and hospitalization, lymphatic complications, heart transplant, and death. Results Forty-three patients (median age, 10 years [IQR, 8-11]; 20 [47%] boys, 23 [53%] girls) were included in the study. Lymphatic abnormalities progressed in 19 individuals after Fontan completion (distribution of lymphatic classifications: type 1, 23; type 2, 11; type 3, 6; type 4, 3 vs type 1, 10; type 2, 18; type 3, 10; type 4, 5; P = .04). Compared with individuals showing no progression of lymphatic abnormalities, those progressing to a high-grade lymphatic classification had longer postoperative drainage (median time, 9 days [IQR, 6-14] vs 17 days [IQR, 10-23]; P = .04) and hospitalization (median time, 13 days [IQR, 9-25] vs 26 days [IQR, 18-30]; P = .03) after Fontan completion and were more likely to develop chylothorax (12% [three of 24] vs 75% [six of eight]; P < .01) and/or protein-losing enteropathy (0% [0 of 24] vs 38% [three of eight]; P < .01) during a median follow-up of 8 years (IQR, 5-9). Progression to any type was not associated with an increased risk of adverse events. Conclusion The study demonstrated that lymphatic structural abnormalities may progress in select individuals with single ventricle physiology after Fontan completion, and progression of abnormalities to a high-grade classification was associated with worse postoperative outcomes. Keywords: Congenital Heart Disease, Glenn, Fontan, Lymphatic Imaging, Cardiovascular MRI Supplemental material is available for this article. Published under a CC BY 4.0 license.

Targeted treatment in complex lymphatic anomaly: a case of synergistic efficacy of trametinib and sirolimus.

Repurposing anticancer drugs to vascular malformations has significantly improved patient outcomes. Complex Lymphatic Anomalies (CLA) are part of the spectrum of lymphatic malformations (LMs) that share similar oncogenic mutations to cancer. We report the case of a young patient with highly symptomatic CLA who was initially treated with sirolimus, due to the frequent involvement of the PI3K-AKT-mTOR pathway in CLA pathogenesis. Despite an initial reduction in symptoms, sirolimus progressively lost its effectiveness. After an unsuccessful attempt with trametinib alone, sirolimus was added to trametinib and resulted in a significant, rapid and sustained improvement in symptoms. This suggests that, contrary to current dogmas, combination therapy using sub-therapeutic doses targeting both the PI3K and RAS pathways retains efficacy without generating the toxicity known for combination therapies, and is beneficial in the management of CLAs and potentially other vascular anomalies.

Differential Diagnosis of Generalized Cystic Lymphangiomatosis: A Literature Review.

BACKGROUND: Generalized cystic lymphangiomatosis (GCL) is a rare disease characterized by the widespread proliferation of lymphatic vessels, often seen in the pediatric patient group. Imaging techniques are instrumental in revealing the extent and morphological features of the disease. OBJECTIVE: The objective of this study is to interpret the radiological findings of GCL and address the differential diagnosis between GCL and other lymphatic malformations in light of the relevant literature data. METHODS: The sample of this retrospective study consisted of six pediatric patients, four males and two females, diagnosed with GCL based on clinical, radiological, and histopathological findings between 2015 and 2022. The age of the patients at the time of diagnosis and their symptoms at admission were obtained from the hospital database. Radiological imaging findings were evaluated in detail based on the involved systems (thorax, abdomen, and musculoskeletal). RESULTS: The median age of the sample, 4/6 were male, was 9 years at admission (min. 3, max. 12). The most common symptom at admission was dyspnea, often accompanied by pleural effusion. Bone involvement was the most common extrathoracic finding. Abdominal involvement was primarily asymptomatic, and the spleen was the most frequently involved organ in the abdomen. CONCLUSION: The diagnosis of GCL is challenging because of its rarity and overlapping diseases. Whole-body magnetic resonance imaging is a valuable tool as it reveals the typical radiological features of GCL and how far it has spread throughout the body.

The role of key biomarkers in lymphatic malformation: An updated review.

The lymphatic system, crucial for tissue fluid balance and immune surveillance, can be severely impacted by disorders that hinder its activities. Lymphatic malformations (LMs) are caused by fluid accumulation in tissues owing to defects in lymphatic channel formation, the obstruction of lymphatic vessels or injury to lymphatic tissues. Somatic mutations, varying in symptoms based on lesions' location and size, provide insights into their molecular pathogenesis by identifying LMs' genetic causes. In this review, we collected the most recent findings about the role of genetic and inflammatory biomarkers in LMs that control the formation of these malformations. A thorough evaluation of the literature from 2000 to the present was conducted using the PubMed and Google Scholar databases. Although it is obvious that the vascular endothelial growth factor receptor 3 mutation accounts for a significant proportion of LM patients, several mutations in other genes thought to be linked to LM have also been discovered. Also, inflammatory mediators like interleukin-6, interleukin-8, tumor necrosis factor-alpha and mammalian target of rapamycin are the most commonly associated biomarkers with LM. Understanding the mutations and genes expression responsible for the abnormalities in lymphatic endothelial cells could lead to novel therapeutic strategies based on molecular pathways.

Generalized lymphatic anomaly in adult patients: An eminently radiological diagnosis.

Generalized lymphatic anomaly (GLA) is an uncommon congenital disease secondary to the proliferation of lymphatic vessels in any organ except the central nervous system. GLA has a wide spectrum of clinical and radiological presentations, among which osteolytic lesions are the most widespread, being the ribs the most commonly affected bone. GLA is diagnosed mainly in children and young adults; nevertheless, on rare occasions it can remain asymptomatic and be detected incidentally in older patients. We present an unusual case of GLA in an asymptomatic 54-year-old man who had atypically distributed, purely cystic bone lesions on CT; measuring the Hounsfield (HU) of these lesions enabled us to suspect GLA. This suspicion was confirmed with MRI, PET/CT, CT-guided fine-needle aspiration biopsy, and fluoroscopy-guided percutaneous vertebral biopsy. After surgical resection of one of the lesions, histologic study provided the definitive diagnosis.

Spectrum of lymphatic anomalies in patients with RASA1-related CM-AVM.

BACKGROUND: Capillary malformation-arteriovenous malformation (CM-AVM) is characterized by multifocal fast-flow capillary malformations, sometimes with arteriovenous malformations/fistulas, skeletal/soft tissue overgrowth, telangiectasias, or Bier spots. Lymphatic abnormalities are infrequently reported. We describe seven patients with CM-AVM and lymphatic anomalies. METHODS: Following IRB approval, we identified patients with CM-AVM and lymphatic anomalies seen at the Vascular Anomalies Center at Boston Children's Hospital from 2003 to 2023. We retrospectively reviewed records for clinical, genetic, laboratory, and imaging findings. RESULTS: We found seven patients with CM-AVM and lymphatic abnormalities. Five patients were diagnosed prenatally: four with pleural effusions (including one suspected chylothorax) and one with ascites. Pleural effusions resolved after neonatal drainage in three patients and fetal thoracentesis in the fourth; however, fluid rapidly reaccumulated in this fetus causing hydrops. Ascites resolved after neonatal paracentesis, recurred at 2 months, and spontaneously resolved at 5 years; magnetic resonance lymphangiography for recurrence at age 19 years suggested a central conducting lymphatic anomaly (CCLA), and at age 20 years a right spermatic cord/scrotal lymphatic malformation (LM) was detected. Chylous pericardial effusion presented in a sixth patient at 2 months and disappeared after pericardiocentesis. A seventh patient was diagnosed with a left lower extremity LM at 16 months. Six patients underwent genetic testing, and all had RASA1 mutation. RASA1 variant was novel in three patients (c.1495delinsCTACC, c.434_451delinsA, c.2648del), previously reported in two (c.2603+1G>A, c.475_476del), and unavailable in another. Median follow-up age was 5.8 years (4 months-20 years). CONCLUSION: CM-AVM may be associated with lymphatic anomalies, including pericardial/pleural effusions, ascites, CCLA, and LM.

[Lymphangioma of the scrotum].

INTRODUCTION: Lymphangioma (lymphatic malformation) is a congenital malformation of lymphatic vessels. According to the classification of the International Society for the Study of the Vascular Anomalies, there are macrocystic, microcystic and mixed types of lymphatic malformations. The typical location of the lymphangiomas is the area of large lymphatic collectors (head, neck, axillary areas), while the scrotum is not frequently affected. AIM: To present a rare clinical case of lymphatic malformation of the scrotum with successful minimally invasive treatment (sclerotherapy). MATERIALS AND METHODS: A clinical observation of a 12-year-old child with a diagnosis of "Lymphatic malformation of the scrotum" is presented. From the age of 4, there was a large lesion in the left half of the scrotum. In other clinic, a surgical removal with a diagnosis of "left-sided inguinal hernia", "spermatic cord hydrocele", "isolated left-sided hydrocele" was performed. However, there was a recurrence after the procedure. When contacting the Clinic of pediatrics and pediatric surgery, scrotal lymphangioma was suspected. The diagnosis was confirmed by magnetic resonance imaging. The patient underwent minimally invasive sclerotherapy using the drug "Haemoblock". After 6 months of follow-up, no relapse was seen. CONCLUSION: Lymphangioma (lymphatic malformation) of the scrotum is a rare urological pathology that requires specific diagnosis, in-depth differential diagnosis and treatment by a multidisciplinary team of doctors, including a specialist in the treatment of vascular pathology.

Endoscopic Resection for Vascular Anomalies in Children: A New Standard.

OBJECTIVE: To report an innovative endoscopic surgery for subcutaneous vascular malformations and intramuscular fibro-adipose vascular anomaly (FAVA) at our center. BACKGROUND: Historically, open surgical resection has been the treatment of choice. Recent advances in minimally invasive surgery have led to the successful application of endoscopic resection techniques for the surgical management of diseases of soft tissue. METHODS: Patients who underwent endoscopic resection of vascular anomalies were included in this retrospective review. Data were extracted from our Vascular Anomalies Center database between September 2019 and October 2022, including sex, age, symptoms, diagnosis, sites of surgery, previous treatment, surgery, and follow-up. RESULTS: There were 13 females and 15 males in the current study, with ages ranging from 1 to 17 years. The diagnoses included microcystic lymphatic malformation (LM) (n = 8), Klippel-Trénaunay syndrome (n = 7), venous malformation (n = 6), FAVA (n = 6), and mixed cystic LM (n = 1). Surgical sites included the lower extremity (n = 24), abdominal wall (n = 2), upper extremity (n = 1), and thoracic wall (n = 1). Five patients had an intramuscular lesion (FAVA). The endoscopic technique used 2 or 3 small ports in a gas inflation manner. Surgery included thrombectomy, radical resection, and debulking of vascular anomalies. Postoperative sclerotherapy with bleomycin was performed through a drainage tube in 6 patients with microcystic LM. Technical success was obtained in 27 patients. The conversion to open surgery was performed in one patient owing to the deep location of the lesion. No wound-related complication was observed. CONCLUSIONS: Endoscopic surgery is a minimally invasive, effective, and safe treatment for subcutaneous vascular malformations and intramuscular FAVA. This approach can set a new standard that minimizes wound complications and reduces recovery time in patients undergoing resection for benign soft-tissue lesions.

Sirolimus in the Treatment of Microcystic Lymphatic Malformations: A Systematic Review.

Background: Genetic alterations in lymphatic development can lead to microcystic lymphatic malformations (micro LMs). LMs can have both microcystic and macrocytic components or be exclusively one or the other. LMs can result in serious, sometimes life-threatening, sequelae. Absent consensus guidelines, treatment has been largely empiric. Recent advances in our understanding of the pathogenesis of micro LMs have provided a foundation for novel therapeutic approaches. This review examines clinical data over the last 10 years on the role of sirolimus, an inhibitor of the PI3K/AKT/mTOR signaling pathway implicated in micro LM development, in the treatment of micro LM. Methods and Results: Systematic review of published clinical studies from January 1, 2011, to July 15, 2021, using the PubMed, Google Scholar, and Cochrane Reviews databases, and utilizing delimiters to focus specifically on sirolimus in the treatment of micro LM. A total of 16 studies were identified (13 case studies or case reviews; 3 prospective) that included 52 subjects treated with topical (n = 15) or oral (n = 37) sirolimus for micro LM. Clinically meaningful, long-term improvement (up to 3 years) was noted in 92% (46/50), mostly previously treated subjects. Sirolimus yielded improvements in key manifestations such as lymphatic leakage, bleeding, vesicle bulk, pain, and skin discoloration. Some subjects experienced a rapid onset of effect (within 2 weeks). No unexpected adverse events were seen. Conclusion: Sirolimus appears to be an effective and safe option in the management of cutaneous and complex micro LM. However, prospective, controlled trials are clearly needed to accurately elucidate the benefits and risks of sirolimus in the management of micro LM. ClinicalTrials.gov Identifier: NCT05050149.

Classification specific lymphatic malformations management on head and neck in children.

OBJECTIVE: The aim of this study was to retrospectively analyze the outcomes from surgical and nonsurgical treatments for head and neck lymphatic malformations (LMs) in children. STUDY DESIGN: Fifty-eight patients were divided into a surgical group (22) and a nonsurgical group (36). The surgical group contained microcystic LMs in the tongue treated by surgery or with sclerotherapy. The nonsurgical group contained macrocystic and mixed LMs in floor of the mouth, neck, face, submandibular region, maxillofacial region and neck treated by sclerotherapy or with microwave ablation (MWA). RESULTS: In the surgical group, the mean follow-up time was 44 ± 15.3 months. At last follow-up, 15 LMs (68.2%) were completely controlled, 3 LMs (13.6%) were stable without need for further treatment, and 4 LMs (18.2%) were persistent. In the nonsurgical group, the median follow-up time was 23.5 months (13.0, 32.8). At last follow-up, 28 LMs (77.8%,) have a volume reduction rate of >50%, and 6 LMs (16.7%.) have the complication. CONCLUSIONS: Surgery is suitable for microcystic LMs in the early stage with clear boundary and becomes limited for them in the late stages due to diffuse lesions. Sclerotherapy is effective for macrocystic and mixed LMs. Sclerotherapy with MWA is exceptionally effective for large cystic LMs with multiple compartments.

A nomogram for predicting sclerotherapy response for treatment of lymphatic malformations in children.

PURPOSE: In this manuscript, we purposed to identify the prognostic factors for treatment of lymphatic malformations in children using polidocanol foam combined with pingyangmycin and to construct nomogram for predicting sclerotherapy response. METHODS: A retrospective analysis of 77 children having LMs who underwent sclerotherapy using polidocanol foam combined with pingyangmycin under ultrasound display from January 2017 to April 2020 was done. The clinical response was graded as excellent (≥ 90%), good (≥ 50%, < 90%), and poor (< 50%). More than 50% was considered as acceptable response. Prognostic factors were identified by Pearson's Chi-square or Fisher's exact test and multivariable logistic regression model was used to construct a nomogram to predict sclerotherapy response. The discrimination and calibration of nomogram were verified through the receiver operating characteristic cure and calibration plots. RESULTS: The mean number of treatment sessions was 3.1 (range, 1-6). Among 77 patients, 58 patients (75.3%) had excellent response to treatment (≥ 90%) and 68 patients (88.3%) had an acceptable response (≥ 50%, < 90%). Clinical disfigurement (P = 0.014), skin discoloration (P = 0.040), morphological subtype (P < 0.001) and extent of the lesion (P < 0.001) correlated with clinical response to sclerotherapy in LMs. Sclerotherapy response was predicted through nomogram constructed in this study, which shows good calibration and discrimination. Also, focal lesion and macrocystic or mixed morphological subtype lesion were seen more often in lower number of treatment sessions among the patients with excellent response. CONCLUSIONS: An acceptable response to sclerotherapy using polidocanol foam combined with pingyangmycin was achieved in majority of LMs in children with extremely low complication rates. Nomogram based on the prognostic factors of sclerotherapy response for LMs in children was shown to possess an excellent performance to predict the probability of LMs sclerotherapy response.

Topical sirolimus solution for lingual microcystic lymphatic malformations in children and adults (TOPGUN): study protocol for a multicenter, randomized, assessor-blinded, controlled, stepped-wedge clinical trial.

BACKGROUND: Lingual microcystic lymphatic malformations (LMLMs) are rare congenital vascular malformations presenting as clusters of cysts filled with lymph fluid or blood. Even small well-limited lesions can be responsible for a heavy burden, inducing pain, aesthetic prejudice, or oozing, bleeding, infections. The natural history of LMLMs is progressive worsening punctuated by acute flares. Therapeutic options include surgery, laser excision, and radiofrequency ablation but all are potentially detrimental and expose to local relapse. Therefore, the management frequently relies on a "watchful waiting" approach. In complicated LMLMs, treatment with oral sirolimus, a mammalian target of rapamycin (mTOR) inhibitor, is often used. Topical applications of sirolimus on the buccal mucosae have been reported in other oral diseases with good tolerance and none to slight detectable blood sirolimus concentrations. We aim to evaluate the efficacy and safety of a 1 mg/mL sirolimus solution applied once daily on LMLM of any stage in children and adults after 4, 8, 12, 16, 20, and 24 weeks of treatment compared to usual care (no treatment). METHODS: This is a randomized, multicentric study using an individually randomized stepped-wedge design over 24 weeks to evaluate topical application of a 1 mg/mL sirolimus solution once daily, on LMLM, versus usual care (no treatment), the control condition. Participants begin with an observational period and later switch to the intervention at a randomized time (week 0, 4, 8, or 12). Visits occur every 4 weeks, either in the study center or by teleconsulting. The primary outcome will be the evaluation of global severity of the LMLM on monthly standardized photographs by 3 independent blinded experts using the physical global assessment (PGA) 0 to 5 scale. Secondary outcomes will include lesion size measurement and quality of life assessment, investigator, and patient-assessed global disease and specific symptoms (oozing, bleeding, sialorrhea, eating impairment, taste modification, aesthetic impairment, pain, and global discomfort) assessment. A biological monitoring will be performed including residual blood sirolimus concentration and usual laboratory parameters. DISCUSSION: Given the disappointing state of current treatment options in LMLMs, topical sirolimus could become firstline therapy in treating LMLMs if its efficacy and safety were to be demonstrated. TRIAL REGISTRATION: ClinicalTrials.gov NCT04128722 . Registered on 24 September 2019. EudraCT: EUCTR2019-001530-33-FR Sponsor (University Hospital Center of Tours - CHRU Tours): DR190041-TOPGUN French regulatory authorities: ID RCB: 2019-001530-33.

[Neonatal sepsis by Citrobacter Freundii as a debut of cystic lymphatic malformation]. / Sepsis neonatal por Citrobacter Freundii como debut de malformación linfática quística.

Cystic lymphatic malformation (CLM) is a rare and benign entity caused by alterations in the embryological development of lymphatic structures. Its typical location is in the head and neck, although it has also been described at the abdominal level. It may not be evident in the first stages of life and its first manifestation may be a complication such as abdominal distension, hemorrhage, or sepsis, which may put the patient's life at risk. Surgical treatment is increasingly discussed, and less invasive techniques are proposed. OBJECTIVE: To describe an uncommon presentation of CLM, radiographic findings, complications, differential diagnosis, and both invasive and more conservative treatments. CLINICAL CASE: Newborn female infant consulted for fever and irritability, without specific signs on physical examination, with suspicion of sepsis. Ultrasonography showed a complex septate mass with cysts of different sizes encompassing the mesenteric vessels, supravesical location. In its most ante rior aspect, it presented a greater echogenicity that corresponded to the superinfected component. Magnetic resonance imaging identified a multitabulated cystic tumor corresponding to a complica ted mesenteric lymphangioma with signs of infection. Due to its size, which compressed the vena cava and the associated signs of complication, complete resection was decided with good subsequent evolution. CONCLUSION: The treatment of CLM in pediatric age is increasingly individualized and can vary from surgical resection to less invasive approaches that could reduce acute intraoperative or postoperative complications and mortality. In our case, the infection acted as sclerotherapy, mana ging to delimit the CLM and helping to improve the prognosis.

Complex lymphatic malformations in pediatrics: a review of treatment options.

INTRODUCTION: Lymphatic malformations (LMs) are low-flow lesions resulting from abnormalities in the development of lymphatics. The management of these lesions is complex and involve the collaboration of many specialties. The purpose of this review is to summarize current knowledge regarding the different therapeutic options used in complex lymphatic malformations, analyzing their indications, efficacy and complications. EVIDENCE ACQUISITION: A search was made using the algorithm: "(lymphatic abnormality OR lymphatic malformation OR lymphangioma OR cystic hygroma) AND (extensive OR giant OR complex) AND (therapeutics OR treatment) AND (child OR children)". Of the 120 articles found, 53 were included. EVIDENCE SYNTHESIS: Historically, surgery was the treatment of choice for this type of lesions. However, excision was often incomplete, associated with high rates of recurrence and severe complications. The use of sclerotherapy emerged as a minimal invasive option appropriate in selected cases as a single or adjuvant therapy. Inhibitors of the mammalian target of rapamycin, such as sirolimus, now play a central role in the treatment of complex malformations resistant to sclerotherapy, recurrent after surgery or more extensive malformations that affect vital structures. Other therapeutic options as sildenafil and laser ablation are also recognized as effective in selected cases. CONCLUSIONS: Looking through the literature over the last decade authors realize that surgery had gradually been replaced by less invasive options such as sirolimus with or without adjuvant sclerotherapy. In conclusion, each treatment option seems to have its own indications and characteristics, which must be considered in therapeutic decision and individualized for each patient.

Vascular and Lymphatic Malformations: Perspectives From Human and Vertebrate Studies.

Vascular malformations, affecting ≈1% to 1.5% of the population, comprise a spectrum of developmental patterning defects of capillaries, arteries, veins, and/or lymphatics. The majority of vascular malformations occur sporadically; however, inherited malformations exist as a part of complex congenital diseases. The malformations, ranging from birthmarks to life-threatening conditions, are present at birth, but may reveal signs and symptoms-including pain, bleeding, disfigurement, and functional defects of vital organs-in infancy, childhood, or adulthood. Vascular malformations often exhibit recurrent patterns at affected sites due to the lack of curative treatments. This review series provides a state-of-the-art assessment of vascular malformation research at basic, clinical, genetic, and translational levels.

Lymphatic Malformations: Genetics, Mechanisms and Therapeutic Strategies.

Lymphatic vessels maintain tissue fluid homeostasis by returning to blood circulation interstitial fluid that has extravasated from the blood capillaries. They provide a trafficking route for cells of the immune system, thus critically contributing to immune surveillance. Developmental or functional defects in the lymphatic vessels, their obstruction or damage, lead to accumulation of fluid in tissues, resulting in lymphedema. Here we discuss developmental lymphatic anomalies called lymphatic malformations and complex lymphatic anomalies that manifest as localized or multifocal lesions of the lymphatic vasculature, respectively. They are rare diseases that are caused mostly by somatic mutations and can present with variable symptoms based upon the size and location of the lesions composed of fluid-filled cisterns or channels. Substantial progress has been made recently in understanding the molecular basis of their pathogenesis through the identification of their genetic causes, combined with the elucidation of the underlying mechanisms in animal disease models and patient-derived lymphatic endothelial cells. Most of the solitary somatic mutations that cause lymphatic malformations and complex lymphatic anomalies occur in genes that encode components of oncogenic growth factor signal transduction pathways. This has led to successful repurposing of some targeted cancer therapeutics to the treatment of lymphatic malformations and complex lymphatic anomalies. Apart from the mutations that act as lymphatic endothelial cell-autonomous drivers of these anomalies, current evidence points to superimposed paracrine mechanisms that critically contribute to disease pathogenesis and thus provide additional targets for therapeutic intervention. Here, we review these advances and discuss new treatment strategies that are based on the recently identified molecular pathways.

Efficacy of Initial Sirolimus Therapy for 27 Patients with Intractable Lymphatic Malformations.

OBJECTIVE/HYPOTHESIS: To evaluate the efficacy of initial sirolimus therapy in the treatment of intractable head and neck lymphatic malformations (LMs) in children. STUDY DESIGN: Prospective open-label study. METHODS: In this study, Twenty-seven children diagnosed with LMs were given oral sirolimus as primary treatment over a minimum 6-month trial. The major parameter to evaluate therapeutic outcome was percentage of lesion volume change compared with baseline. Average serum sirolimus concentrations, and adverse side effects, were monitored throughout the study period. RESULTS: Fifteen girls and twelve boys, average age 27 months (16 days-171 months), constitute the study group. Treatment was deemed effective for twenty-three participants, judged as fair in seven, good in nine, and excellent in seven. Two patients had minimal improvement, and two had increased volume to some degree. Effectiveness differed among LMs subtypes with responsiveness of macrocystic LMs exceeding that of microcystic LMs (P < .05). Adverse drug reactions totaled 27 events in ten patients, the majority being mild with upper respiratory infections being most common. CONCLUSIONS: Sirolimus as initial therapy is effective in decreasing lesion volume in intractable LMs in head and neck region, especially in macrocystic subtypes. Although most cases cannot be completely cured, side effects are few and tolerable. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:1902-1908, 2021.

Menstrual disorders associated with sirolimus treatment.

INTRODUCTION: Sirolimus has become a pillar in the treatment of vascular anomalies due to its inhibition of the mammalian target of rapamycin (mTOR). Adverse effects include metabolic and hematologic disorders among others, although menstrual disorders have not been well described. MATERIALS AND METHODS: Retrospective review of patients with vascular anomalies on sirolimus treatment was performed. Patients presenting menstrual alterations were included. MAIN RESULTS: One hundred and thirty-six patients with vascular anomalies on treatment with sirolimus were reviewed, finding seven women out of 74 (9.4%) who presented menstrual alterations attributable to the treatment. These seven patients presented with different vascular malformations and three showed pathogenic variants in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) in affected tissue. Partial response in six and stability in one patient was obtained after treatment, administered for an average of 27.5 months (6-48). Five patients have completed treatment and two patients continue on after 12 and 15 months, respectively. All patients reported regular menstrual cycles prior to sirolimus treatment. One patient presented with amenorrhea for 4 months after treatment initiation that later spontaneously resolved. The other six patients presented with hypermenorrhea, four of them associating metrorrhagia. Most patients presented with mild menstrual alterations, without needing dose reduction or withdrawal, although one discontinued sirolimus due to hypermenorrhea, metrorrhagia, and hematuria. After sirolimus withdrawal, regular menstrual cycles were restored in five patients. CONCLUSION: Sirolimus treatment can produce menstrual disorders as adverse effects. Although mild and reversible upon dose reduction or cessation of treatment, patients and physicians should be aware on this potential side effect.

A novel method for isolating lymphatic endothelial cells from lymphatic malformations and detecting PIK3CA somatic mutation in these isolated cells.

PURPOSE: Tissue disaggregation and the cell sorting technique by surface markers has played an important role in isolating lymphatic endothelial cells (LECs) from lymphatic malformation (LM). However, this technique may have the drawback of impurities or result in isolation failure because it is dependent on surface marker expressions, the heterogeneity of which has been found in the lymphatic system. We developed a novel method for isolating LM-LECs without using whole tissue disaggregation. METHODS: Seven LM surgical specimens were collected from seven patients with LMs. LM-LECs were detached from the LM cyst wall by "lumen digestion" and irrigating the cystic cavity with trypsin, and maintained in culture. RESULTS: The cells formed a monolayer with a cobblestone-like appearance. Immunohistochemistry and quantitative RT-PCR of these cells revealed high expression of lymphatic-specific genes, confirming their identity as LM-LECs. The whole-exome sequencing and PIK3CA sequencing of these cells revealed somatic mutations in PIK3CA in all cases. CONCLUSIONS: We established a novel technique for isolating LM-LECs from LM tissue by "lumen digestion" without whole-tissue disaggregation. The limited incorporation of non-LM LECs in the isolate in our method could make it an important tool for investigating the heterogeneity of gene expression as well as mutations in LM-LECs.

The YAP signaling pathway promotes the progression of lymphatic malformations through the activation of lymphatic endothelial cells.

BACKGROUND: To investigate whether the YAP/TAZ (Yes-associated protein/transcriptional coactivator with PDZ binding motif) pathway contributes to the pathogenesis of lymphatic malformations (LMs). METHODS: YAP, TAZ, CTGF (connective tissue growth factor), and Ki-67 were detected in LMs by immunohistochemistry. The colocalization of YAP and Ki-67 was analyzed by double immunofluorescence. Pearson's correlation and cluster analyses were performed to analyze the relationships between these proteins. Human dermal lymphatic endothelial cells (HDLECs) were used for mechanistic investigation. Rat models of LMs were established to investigate the role of the YAP pathway in LM development. RESULTS: Compared with those in normal skin, the expression levels of YAP, TAZ, CTGF, and Ki-67 were significantly upregulated in lymphatic endothelial cells (LECs) of LMs. Interestingly, YAP and CTGF presented much higher expression levels in infected LMs. In experiments in vitro, lipopolysaccharide (LPS) enhanced the expression of YAP in a concentration- and time-dependent manner via the increased phosphorylation of Erk1/2 (extracellular signal-regulated kinase 1/2). Moreover, the proliferation, invasion, and tubule formation of HDLECs increased significantly in accordance with the activation of the YAP signaling pathway. Furthermore, LM rat models validated that LPS facilitated the development of LMs, which was dependent on the activation of YAP. CONCLUSIONS: The data reveal that activation of the YAP signaling pathway in LECs may play a crucial role in the progression of LMs. IMPACT: Compared with that in normal skin, the YAP signaling pathway was activated in LECs of LMs. Inhibiting the YAP signaling pathway attenuated the proliferation, invasion, and tubule formation of HDLECs. Additionally, the activation of the YAP signaling pathway could promote LM development in a rat model. Activation of the YAP signaling pathway in LECs may play a crucial role in the progression of LMs. The YAP signaling pathway was activated in LMs. Inhibition of the YAP signaling pathway could promote regression of the lesions.