Oral Sirolimus: An Option in the Management of Neonates with Life-Threatening Upper Airway Lymphatic Malformations

Management and Outcomes of Pediatric Lymphatic Malformations: A Systematic Review From the APSA Outcomes and Evidence-Based Practice Committee

BACKGROUND

Significant variation in management strategies for lymphatic malformations (LMs) in children persists. The goal of this systematic review is to summarize outcomes for medical therapy, sclerotherapy, and surgery, and to provide evidence-based recommendations regarding the treatment.

METHODS

Three questions regarding LM management were generated according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Publicly available databases were queried to identify articles published from January 1, 1990, to December 31, 2021. A consensus statement of recommendations was generated in response to each question.

RESULTS

The initial search identified 9326 abstracts, each reviewed by two authors. A total of 600 abstracts met selection criteria for full manuscript review with 202 subsequently utilized for extraction of data. Medical therapy, such as sirolimus, can be used as an adjunct with percutaneous treatments or surgery, or for extensive LM. Sclerotherapy can achieve partial or complete response in over 90% of patients and is most effective for macrocystic lesions. Depending on the size, extent, and location of the malformation, surgery can be considered.

CONCLUSION

Evidence supporting best practices for the safety and effectiveness of management for LMs is currently of moderate quality. Many patients benefit from multi-modal treatment determined by the extent and type of LM. A multidisciplinary approach is recommended to determine the optimal individualized treatment for each patient.

LEVEL OF EVIDENCE: 4

Sirolimus for Pediatric Cervicofacial Lymphatic Malformation: A Systematic Review and Meta-Analysis

OBJECTIVE

This study is a systematic review and meta-analysis of the efficacy and safety of sirolimus in the management of pediatric cervicofacial lymphatic malformations (LMs).

DATA SOURCES

EMBASE, Medline, Scopus, and Cochrane databases were searched, along with the reference list of all included articles.

REVIEW METHODS

The study protocol was registered with PROSPERO and a systematic literature search strategy was designed and conducted with the aid of a medical librarian. All studies including case reports were included, with pooled analysis of raw data. A meta-analysis was conducted of magnetic resonance imaging (MRI), clinical, and airway outcomes.

RESULTS

Thirteen case series and five individual case reports were included. Meta-analysis showed 78% (95% CI 57%-94%) of 62 patients had a reduction in LM volume, on MRI criteria, by 20% or more, and 32% (95% CI 11%-57%) had a reduction of 50% or more. Further meta-analysis showed 97% (95% CI 88%-100%) of 78 patients reported some clinical improvement on sirolimus. Sirolimus may be of particular value in management of airway LMs; out of 27 tracheostomy-dependent patients, meta-analysis showed 33% (95% CI 1%-78%) were decannulated after starting sirolimus. Individual patient meta-analysis on 24 individuals showed a statistically significant better response to sirolimus when initiated under the age of 2 years.

CONCLUSION

This review and meta-analysis support the efficacy of sirolimus in pediatric LMs of the head, neck, and airway. A large multi-center trial is needed to further explore its role and limitations. Laryngoscope, 134:2038-2047, 2024.

Infantile hemangioma: the common and enigmatic vascular tumor

Infantile hemangioma (IH) is a benign vascular tumor that occurs in 5% of newborns. The tumor follows a life cycle of rapid proliferation in infancy, followed by slow involution in childhood. This unique life cycle has attracted the interest of basic and clinical scientists alike as a paradigm for vasculogenesis, angiogenesis, and vascular regression. Unanswered questions persist about the genetic and molecular drivers of the proliferating and involuting phases. The beta blocker propranolol usually accelerates regression of problematic IHs, yet its mechanism of action on vascular proliferation and differentiation is unclear. Some IHs fail to respond to beta blockers and regrow after discontinuation. Side effects occur and long-term sequelae of propranolol treatment are unknown. This poses clinical challenges and raises novel questions about the mechanisms of vascular overgrowth in IH.

Mammalian target of rapamycin inhibitors: A new-possible approach for in-utero medication therapy

The mammalian/mechanistic target of rapamycin (mTOR) is a protein kinase that plays a crucial role in regulating cellular growth, metabolism, and survival. Although there is no absolute contraindication for the use of mTOR inhibitors during pregnancy, the specific fetal effects remain unknown. Available data from the past 2 decades have examined the use of mTOR inhibitors during pregnancy in patients with solid organ transplantation, showing no clear link to fetal complications or structural abnormalities. Recently, a handful of case reports and series have described transplacental therapy of mTOR inhibitors to control symptomatic and complicated pathologies in the fetus. The effect of these agents includes a significant reduction in lesion size in the fetus and a reduced need for mechanical ventilation in neonates. In this context, we delve into the potential of mTOR inhibitors as in-utero therapy for fetal abnormalities, with a primary focus on lymphatic malformation (LM) and cardiac rhabdomyoma (CR). While preliminary reports underscore the efficacy of mTOR inhibitors for the treatment of fetal CR and fetal brain lesions associated with tuberous sclerosis complex, chylothorax, and LMs, additional investigation and clinical trials are essential to comprehensively assess the safety and efficacy of these medications.

Rapid response with good toleration of sirolimus for life-threatening neonatal lymphatic malformations

Introduction

Lymphatic malformations (LMs) are rare vascular anomalies predominantly affecting infants, which can be debilitating or life-threatening when complicated with intralesional bleeding or infection. Effective and safe management strategies are essential in such cases.

Case presentation

We report a case series involving four Chinese neonates with life-threatening LMs, initially treated with oral sirolimus. All patients achieved rapid relief and sustained remission, using a lower sirolimus dosage than previously recommended. Furthermore, adverse events were rarely recorded during follow-up.

Conclusion

Sirolimus can be considered a promising choice for neonates with intricate and life-threatening LMs. Initiation with a reduced sirolimus dose is advisable.

Sirolimus treatment for paediatric head and neck lymphatic malformations: a systematic review

PURPOSE

This PRISMA-compliant systematic review aimed to assess risks and benefits of sirolimus treatment for paediatric lymphatic malformations by focusing not only on treatment efficacy but also on possible treatment-related adverse events, and treatment combinations with other techniques.

METHODS

Search criteria were applied to MEDLINE, Embase, Web of Science, Scopus, Cochrane Library, and ClinicalTrials.gov databases and included all studies published up to March 2022 reporting paediatric lymphatic malformations treated with sirolimus. We selected all original studies that included treatment outcomes. After the removal of duplicates, selection of abstracts and full-text articles, and quality assessment, we reviewed eligible articles for patient demographics, lymphatic malformation type, size or stage, site, clinical response rates, sirolimus administration route and dose, related adverse events, follow-up time, and concurrent treatments.

RESULTS

Among 153 unique citations, 19 studies were considered eligible, with reported treatment data for 97 paediatric patients. Most studies (n = 9) were case reports. Clinical response was described for 89 patients, in whom 94 mild-to-moderate adverse events were reported. The most frequently administered treatment regimen was oral sirolimus 0.8 mg/m2 twice a day, with the aim of achieving a blood concentration of 10-15 ng/mL.

CONCLUSION

Despite promising results for sirolimus treatment in lymphatic malformation, the efficacy and safety profile of remains unclear due to the lack of high-quality studies. Systematic reporting of known side effects, especially in younger children, should assist clinicians in minimising treatment-associated risks. At the same time, we advocate for prospective multicentre studies with minimum reporting standards to facilitate improved candidate selection.

French national diagnosis and care protocol (PNDS, protocole national de diagnostic et de soins): cystic lymphatic malformations

Cystic lymphatic malformations (LMs) are rare chronic conditions which management differs according to the type (macrocystic LMs, microcystic LMs or both). Studies are lacking due to rarity of the pathology. We aimed to establish a French National Diagnosis and Care Protocol (PNDS: Protocole National de Diagnostic et de Soins), to provide health professionals with free open access synthesis on optimal management and care of patients with LMs ( https://www.has-sante.fr/upload/docs/application/pdf/2021-03/malformations_lymphatiques_kystiques_-_pnds.pdf ). The process included a critical review of the literature and multidisciplinary expert consensus. LMs are congenital but are not always discovered at birth. Nearly 75% of them are located in the head and neck because of the highly dense lymphatic system in this region. Physical examination (showing painless masses with normal skin color and depressible consistency, or cutaneous/mucosal lymphangiectasia) and color Doppler ultrasonography, usually allow for diagnosis. MRI (involving T2 sequences with fat saturation in at least two spatial planes) is the tool of choice for evaluating anatomical extension, characterizing lesions (microcystic and macrocystic), and before considering therapeutic management. A biopsy, coupled to a blood sample, can also be used for molecular biology analyses, to search for activating mutations of the PIK3CA gene, particularly with LM integrating in a syndromic form (CLOVES or Klippel-Trenaunay syndrome) but also in certain isolated (or common) LMs. The spontaneous evolution of LMs, in particular microcystic forms, is often toward progressive aggravation, with an increase in the number of vesicles, thickening, increased oozing and bleeding, while pure macrocystic LMs may regress due to "natural sclerosis", i.e. fibrosis secondary to an inflammatory reorganization after common infantile infections. In case of voluminous LMs or syndromic forms, functional and psychological repercussions can be major, deteriorating the patient's quality of life. LMs must be treated by physicians integrated in multidisciplinary teams, and be personalized. Management is a life-long process that involves one or several of these therapies: conservative management, physical therapy (compression), sclerotherapy, surgery, drugs such as mTOR inhibitors (sirolimus), that has shown efficacy in decreasing the volume of LMs, and, more recently, PI3K-inhibitors in syndromic forms. Psychological and social support is necessary, taking into account the patient and his family.

Sirolimus-induced pulmonary hemorrhage of an infant with massive cervicofacial lymphatic malformation: A case report

Lymphatic malformations (LMs) are uncommon congenital abnormalities of the lymphatic system. As more than half of these lesions develop in the head and neck, LMs can be life-threatening if associated with airway involvement. LMs necessitate a multidisciplinary treatment approach, frequently including surgery and sclerotherapy. We present a case report of a 32-week pre-term male infant with a massive cervicofacial LM necessitating delivery via ex-utero intrapartum treatment (EXIT). The patient was treated with numerous rounds of sclerotherapy, systemic sirolimus, and surgical debulking, but ultimately died at 4 months of age due to acute pulmonary hemorrhage, which may have been related to sirolimus due to the absence of any other associable organ involvement or derangement. We document the patient's clinical course and treatment regimen, highlighting the myriad modalities employed to treat these challenging lesions, and describe a potentially lethal complication of sirolimus therapy not previously described in the treatment of pediatric LM.

Alpelisib for the treatment of PIK3CA-related head and neck lymphatic malformations and overgrowth

PURPOSE

PIK3CA-related overgrowth spectrum (PROS) conditions of the head and neck are treatment challenges. Traditionally, these conditions require multiple invasive interventions, with incomplete malformation removal, disfigurement, and possible dysfunction. Use of the PI3K inhibitor alpelisib, previously shown to be effective in PROS, has not been reported in PIK3CA-associated head and neck lymphatic malformations (HNLMs) or facial infiltrating lipomatosis (FIL). We describe prospective treatment of 5 children with PIK3CA-associated HNLMs or head and neck FIL with alpelisib monotherapy.

METHODS

A total of 5 children with PIK3CA-associated HNLMs (n = 4) or FIL (n = 1) received alpelisib monotherapy (aged 2-12 years). Treatment response was determined by parental report, clinical evaluation, diary/questionnaire, and standardized clinical photography, measuring facial volume through 3-dimensional photos and magnetic resonance imaging.

RESULTS

All participants had reduction in the size of lesion, and all had improvement or resolution of malformation inflammation/pain/bleeding. Common invasive therapy was avoided (ie, tracheotomy). After 6 or more months of alpelisib therapy, facial volume was reduced (range 1%-20%) and magnetic resonance imaging anomaly volume (range 0%-23%) were reduced, and there was improvement in swallowing, upper airway patency, and speech clarity.

CONCLUSION

Individuals with head and neck PROS treated with alpelisib had decreased malformation size and locoregional overgrowth, improved function and symptoms, and fewer invasive procedures.

Multispecialty Approach to a Very Large Congenital Head and Neck Cystic Lymphatic Malformation in an Infant Born by SARS-CoV-2 Positive Mother—A Case Report

Masses of the head and neck are often diagnosed prenatally and require special care due to the risk of airway obstruction. The EXIT procedure is a preferable mode of delivery. A congenital cystic lymphatic malformation is one of the most common lesions of the cervical region described in neonates. The treatment consists of different strategies and involves the cooperation of multiple specialists. Up to now, no guidelines or protocols are available. We report a case of a congenital cystic lymphatic malformation of the head and neck delivered during the EXIT procedure by a mother who was SARS-CoV-2 positive. We analyzed clinical characteristics, radiologic features, and treatment with injections of sclerotic agents and orally administrated sirolimus. Sirolimus seems a valuable and safe therapeutic option for treating lymphatic malformations, especially with adjunct therapies.

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.

Efficacy of sirolimus in children with lymphatic malformations of the head and neck

Purpose

Children with extensive lymphatic malformations of the head and neck often suffer from functional impairment and aesthetic deformity which significantly affect the quality of life and may be life-threatening. Treatment with sirolimus has the potential to improve symptoms and downsize lymphatic malformations. This systematic review summarizes the current information about sirolimus treatment of lymphatic malformations of the head and neck in children, its efficacy and side effects.

Methods

A systematic search of the literature regarding studies on sirolimus treatment of children with lymphatic malformations of the head and neck was performed in PubMed, Embase, and Google Scholar up to July 2021 with the search terms “lymphatic malformation”, “lymphangioma”, “cystic hygroma”, “low-flow malformation”, “sirolimus”, “rapamycin”, “mTOR inhibitor” and “children”.

Results

In all, 28 studies including 105 children from newborn to 17 years treated with sirolimus for lymphatic malformations of the head and neck were analyzed. The most frequent initial dose was 0.8 mg/m² per dose, twice daily at 12-h interval. The target blood level differed between studies, 10–15 ng/mL and 5–15 ng/mL were most often used. More than 91% of the children responded to sirolimus treatment which lasts from 6 months to 4 years. Typical side effects were hyperlipidemia, neutropenia and infections.

Methods

Sirolimus could be an effective treatment for children with large complicated lymphatic malformations of the head and neck. As not all patients will benefit from treatment, the decision to treat sirolimus should be made by a multidisciplinary team.

Lymphatic malformations adjacent to the airway in neonates: Risk factors for outcome

PURPOSE

To evaluate imaging, treatment, and outcomes in neonates with a lymphatic malformation (LM) adjacent to the airway and to evaluate risk factors that can predict outcome.

METHODS

A retrospective case series was conducted of ten patients treated between January 2011 and July 2019. The main outcome measures included airway compromise and clinical response to sclerotherapy ± surgery. Categorical data were compared using the Fisher's exact test.

RESULTS

Ex-utero intrapartum therapy was performed in four cases, among whom one died due to sepsis. All patients underwent schlerotherapy, with surgical debulking in two. Four patients showed a good clinical response, and five started experimental systemic treatment. Patients with bilateral disease and patients with an LM with >180° tracheal surrounding were significantly at risk for airway compromise (bilateral: n = 6/6 versus n = 0/4, p = 0.005; >180°: n = 5/5 versus n = 1/5, p = 0.048). The need for LM treatment in the neonatal period was indicative of a poor clinical response ('non-responders' 5/6, 'responders' 0/4; p = 0.048).

CONCLUSIONS

This study indicates that bilateral disease and >180° tracheal surrounding are risk factors for airway compromise in neonates with an LM adjacent to the airway. In addition, the need for early treatment seems to be indicative of a poor clinical response.

Intermittent Administration Regimen of Sirolimus for Refractory Cervicofacial Lymphatic Malformation

BACKGROUND

The cervicofacial lymphatic malformations (LMs) often have poor outcomes due to their microcystic component and diffuse infiltration. Mostly, traditional treatments are inadequate for these refractory cases. Recent researches have shown that sirolimus is effective in the treatment of complicated LMs, however, there is still no standard strategy.

OBJECTIVE

To evaluate the efficacy and safety of intermittent oral sirolimus in treating refractory cervicofacial LMs as a second-line treatment.

METHODS

Fifteen pediatric patients of refractory cervicofacial LMs were retrospectively analyzed in this study. All the cases had received traditional therapy before, but could not completely control the symptoms and eliminate lesions. As a remedy, sirolimus was then proceeded with an intermittent administration regimen, that is 3 continuous months as a course and started the next course after 1 month interval. The clinical characteristics, imaging data of patients, the changes in the signs and symptoms observed, and associated adverse effects were collected and analyzed.

RESULTS

The patients initiated sirolimus therapy at the average age of 2.3 years (range 28 days-8 years 9 months). At the end point of the study, 2 patients remained on sirolimus in continuous courses of treatment. Of 13 patients who withdrawn therapy, 4 had restarted due to recurrence of symptoms and re-expansion of LMs. All patients demonstrated reduction in residual LMs and complete disappearance of symptoms during treatment, and 2 patients with complete resolution on imaging. Toxicity was tolerant in this series. There was no patient develop opportunistic or systemic bacterial infection.

CONCLUSIONS

Sirolimus is commended as a second-line treatment to treat intractable cervicofacial LMs after failure of traditional therapy. The intermittent administration regimen is efficacious to completely control symptoms and partially reduce residual lesions with good tolerance and limited side effects.

Antiproliferative therapy with sirolimus and propranolol for congenital vascular anomalies in newborns (Case reports)

We present a series of four newborns diagnosed with complicated congenital vascular anomalies, with different localization: Congenital lymphatic malformation (CLM) on the left hemithorax extending on the left upper limb; congenital hepatic hemangioma (CHH) with important complications in the first 7 weeks of life; Kaposiform hemangioendothelioma (KHE) of the left lower limb complicated with Kasabach Merritt phenomenon (KMM) and most probable diffuse capillary malformation with overgrowth (DCMO). All patients were treated with combined antiproliferative therapy with sirolimus and propranolol. The initial dose of sirolimus was 0.45-0.5 mg/m² with doses adjusted according to plasmatic levels. Therapeutic intervals of sirolimus were considered at plasmatic levels of 7-12 ng/ml. Our aim was to use the lowest therapeutic dose in order to avoid possible side effects. Propranolol was initiated in doses of 0.5-1.0 mg/kg/day and was increased up to 3.0 mg/kg/day depending on tolerability. Following two months, every patient showed a marked reduction in the size of the mass, improvement in overall appearance or even calcification in the liver vascular tumor. No patient showed life threatening side effects to the treatment. Hypertriglyceridemia was the only side effect noted in all patients. This is in accordance with several international studies, which try to demonstrate the importance of sirolimus in neonatal vascular malformations in monotherapy or combined with different drugs.

Efficacy and safety of oral sirolimus for high-flow vascular malformations in real clinical practice

BACKGROUND

Vascular malformations are a complex pathology with few treatment options. In previously published studies, oral sirolimus (rapamycin) has shown promising results in the treatment of low-flow vascular malformations, but its usefulness in high-flow vascular malformations is controversial.

AIM

To evaluate the efficacy and safety of sirolimus for the treatment of high-flow vascular malformations in real-life practice.

METHODS

In a unit specializing in vascular anomalies, patients treated with oral sirolimus for high-flow vascular malformations were located by consulting the drug dispensations. Reviewing the electronic medical records, data on patient demographics, vascular malformation characteristics, treatments, toxicity and clinical course were collected and statistically analysed.

RESULTS

Nine patients with vascular malformations were included: eight had arteriovenous malformation and one had arteriovenous fistula. Six of these malformations were isolated while three were part of a syndrome. Sirolimus was initiated at a dosage of 1-4 mg/day to be taken as a single dose. Partial response was observed in eight of the nine patients (88.9%) with high-flow vascular malformation, while worsening was observed in the remaining patient. The treatment was well tolerated and at the most recent follow-up, five patients remained on treatment with oral sirolimus.

CONCLUSION

Our results show that oral sirolimus is a well-tolerated therapeutic option, with an excellent safety profile, which can be useful in the long-term stabilization of patients with high-flow vascular malformations. Single-daily dosage may improve long-term adherence to treatment without worsening its effectiveness.

A narrative review of the role of sirolimus in the treatment of congenital vascular malformations

OBJECTIVE

Vascular malformations arise from defects in the morphologic development of the vascular system and can have an impact on quality of life and/or lead to severe complications. To date, vascular malformations are frequently managed by invasive techniques, after which recurrence is common. Sirolimus, a downstream inhibitor of the phosphatidylinositol 3 kinase/AKT pathway and best known for its immunosuppressive effect, has been used off-label for lesions for which approved therapies were associated with unsatisfactory results or recurrence. The aim of this study was to review the available data on the effect of sirolimus on the size and symptoms of different types of malformations and to summarize the main safety issues.

METHODS

A literature search in Pubmed, Embase, Web of Science, and SCOPUS was performed. Case reports, case series, and clinical trials evaluating the effect of sirolimus in vascular malformations were eligible for this review. Fully terminated studies published between January 2010 and May 2019 reporting an evaluable response on size and/or symptoms were included. Relevant data on lesion size, symptoms, side effects and duration of treatment were extracted as reported in the study. Additionally, we reported 10 unpublished cases who were treated in UZ Leuven.

RESULTS

The literature review included 68 articles, describing 324 patients. The median duration of therapy was 12 months (range, 1-60 months). After 6 months of treatment, the size of the malformation had at least decreased in 67% of patients with common venous malformations (VM), in 93% of patients with blue rubber bleb nevus syndrome and in all patients with verrucous VM. The size of lymphatic malformations improved in more than 80% of the patients, even in the case of extensive involvement such as in Gorham-Stout disease and generalized lymphatic anomaly. In addition, the majority of patients with syndromic vascular malformations experienced a decrease in size and reported symptoms improved in almost all patients, regardless of the type of malformation. Side effects were common (53%) but usually mild; mucositis and bone marrow suppression were the most common. Regrowth or recurrence of symptoms occurred in 49% of patients who discontinued treatment. Comparable effects were seen in our own patients.

CONCLUSIONS

This review shows that sirolimus is effective in decreasing the size and/or symptoms of particularly lymphatic malformations as well as VMs. Although common, side effects were usually mild. Nevertheless, clinical trials are needed to confirm the safety and effectivity of sirolimus and to identify the required serum levels and duration of treatment.

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.

Lymphatic and Mixed Malformations

Lymphatic and mixed malformations are rare and variable in presentation. They arise due to errors in vascular and lymphatic formation during early embryonic development. This leads to persistent infiltration of lymph fluid into soft tissues and causes a locally invasive mass with pathologic sequelae. Departing from historically descriptive terminology, such as "cystic hygroma," lymphatic malformations are now categorized as macrocystic, microcystic, or mixed lesions, based on size. Advances in imaging modalities, such as ultrasonography and magnetic resonance imaging, have made accurate characterization of these lesions possible and ultimately allow for early diagnosis and implementation of appropriate treatment based on the morphology of the lymphatic malformation. Management of lymphatic malformations can be quite challenging, and a multidisciplinary approach is most effective for optimum aesthetic and functional outcomes. New discoveries in the molecular biology of lymphatic malformations have provided treatment targets and established a role for pharmacotherapy. Sclerotherapy, laser, and radiofrequency ablation have all proven to be effective as minimally invasive treatment options for lymphatic malformations. Surgical intervention has a role in the treatment of focal lesions recalcitrant to these less invasive techniques. Operative planning is dictated by clinical goals, size, anatomic location, characteristics, and extent of infiltration.

Efficacy of Sirolimus in Patients Requiring Tracheostomy for Life-Threatening Lymphatic Malformation of the Head and Neck: A Report From the European Reference Network

Extensive lymphatic malformations (LMs) of the head and neck region may require tracheostomy to secure the airway. Treatment of these life-threatening LMs is usually multimodal and includes sclerotherapy and surgery, among others. Recently, systemic therapy with sirolimus has been introduced as an effective treatment for venous and lymphatic malformations; its efficacy and safety profile in patients with extensive LM requiring tracheostomy are, however, as yet not fully known. We performed a retrospective, multicenter review and identified 13 patients with an extensive LM of the head and neck region, who previously underwent placement of tracheostomy and subsequently received sirolimus treatment with the aim to improve the local respiratory situation and remove the tracheostomy. Under sirolimus therapy, tracheostomy could be reversed in 8/13 (62%) patients, a further 2/13 (15%) patients improved markedly, and removal of the tracheostomy was planned at the time of writing, while 3/13 (23%) patients showed insufficient or absent response to sirolimus, rendering tracheostomy reversal not feasible. The median duration of sirolimus treatment until removal of tracheostomy was 18 months (range, 8 months to 5.6 years). Adverse events of sirolimus therapy were common [10/13 (77%) patients], yet the majority of these were mild [9/10 (90%) patients] and only one severe adverse event was recorded, with ulceration and necrosis at a catheter insertion site. In conclusion, sirolimus can be considered an effective and safe salvage treatment in patients with extensive LM even after placement of a tracheostomy, as closure of the latter was possible in the majority of patients (62%) of our retrospective cohort. A better understanding of when to start sirolimus therapy, of the duration of treatment, and of factors allowing the prediction of treatment response will require further investigation.

Early Adjuvant Medication With the mTOR Inhibitor Sirolimus in a Preterm Neonate With Compressive Cystic Lymphatic Malformation

Cystic lymphatic malformations result from an abnormal embryological development of the lymphatic structures. Here we report on a case of a preterm female baby, born at 34 weeks of gestation, with a voluminous cervicofacial cystic lymphatic malformation responsible for an airway obstruction. An mTOR inhibitor, sirolimus, was started from the first day of life, and was combined with iterative sclerotherapy procedures. This case illustrates a safe and successful early administration of sirolimus in a preterm neonate.