Recent diagnostic advances reveal that lymphatic disease in Noonan syndrome (NS) and other NS-like RASopathies often stems from central conducting lymphatic anomalies (CCLAs). The RAS/MAPK-ERK pathway plays a central role in lymphangiogenesis. Targeting this pathway with MEK-inhibitor trametinib has emerged as a promising therapeutic strategy for managing CCLAs in patients with NS-like RASopathies. This case series assessed the clinical outcomes of trametinib therapy in eight patients with NS-like RASopathies and CCLA, each offering unique insights into the therapeutic efficacy of MEK inhibition. In infants, a lower dose of 0.01 mg/kg/day and earlier discontinuation of trametinib therapy effectively alleviated the symptoms of congenital chylothorax and rescued the lymphatic phenotype, compared to similar published cases. Moreover, four patients aged >11 y showed a slower response and did not achieve complete symptomatic recovery. In conclusion, it is advised to consider trametinib therapy for patients with severe, therapy-refractory CCLA in patients with NS-like RASopathies. However, individual responses to trametinib therapy may vary, with some patients demonstrating more favorable outcomes than others. Further investigation into potential enhancers and suppressors of the lymphatic phenotype is necessary for more accurate treatment predictions. While these factors are likely genetic, we cannot rule out other intrinsic or physiological factors.

Central conducting lymphatic anomaly (CCLA) is a rare and potentially life-threatening vascular malformation characterized by impaired central lymphatic flow. Hydrops fetalis and congenital hydro-/chylothorax are common neonatal presentations; however, diagnosing CCLA poses challenges and requires advanced imaging. Management typically includes supportive therapies with limited effect, such as medium-chain triglyceride (MCT) diet, octreotide or propranolol, and thoracic drainage. Upcoming treatment options with mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MEK) inhibitors have shown promising results in vascular anomalies driven by dysregulated PI3K/AKT/mTOR and RAS/RAF/MAPK signalling pathways. However, data on neonatal use remain scarce. This series describes infants (gestational age 29 + 3–40 + 4 weeks) with neonatal-onset CCLA treated with mTOR and/or MEK inhibitors (age IQR: 27–57 days), detailing clinical presentations, imaging, genetic findings, and outcomes. Genetic testing included germline and somatic variant analysis. Most patients underwent dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL) for diagnosis and to guide management. Pathogenic germline variants were identified in four patients; three had no genetic diagnosis. DCMRL revealed heterogeneous phenotypes; follow-up imaging showed improved lymphatic flow. Substantial clinical improvement occurred following mTOR and/or MEK inhibitor treatment (sirolimus and/or trametinib). In most cases, therapy was tapered within weeks; no relapses occurred (mean follow-up 10.3 months). No deaths or other severe adverse events occurred during inhibitor treatment. Conclusion : This series describes infants with CCLA, treated with mTOR and/or MEK inhibitors early after birth, with rapid improvement possibly reflecting treatment response leading to functional recovery during a critical developmental phase of the lymphatic system. What is Known: • Central conducting lymphatic anomalies are rare conditions associated with high morbidity and mortality, especially in neonates. • Molecular targeted therapies such as MEK inhibitors and mTOR inhibitors show promise in vascular anomalies driven by upregulated PI3K/AKT/mTOR and RAS/RAF/MAPK signalling pathways. What is New: • This series offers a detailed description of the early disease course, clinical variation, and management in infants with congenital chylothorax/hydrops fetalis due to CCLA, contributing to a better understanding of this rare condition in the neonatal period. • Early treatment with low-dose mTOR and/or MEK inhibitors seems effective in infants with CCLA, potentially reducing morbidity and mortality.

Background/objectives: A significant number of COVID-19 cases experience persistent symptoms after the acute infection phase, a condition known as long COVID or post-acute sequelae of COVID-19. Approved prevention and treatment options for long COVID are currently lacking. Given the heterogeneous nature of long COVID, a personalized medicine approach is essential for effective disease management. This study aimed to describe trends in pharmacotherapy from pre-COVID to post-COVID phases to gain insights into COVID-19 treatment strategies and assess whether pre-COVID pharmacotherapy can predict long COVID symptoms as a health status indicator. Methods: In the Precision Medicine for more Oxygen (P4O2) COVID-19 study, 95 long COVID patients were comprehensively evaluated through post-COVID outpatient clinics and study visits. This study focused on descriptive analysis of the pharmacotherapy patterns across different phases: pre-COVID-19, acute COVID, and post-COVID. Furthermore, associations between pre-COVID medication and long COVID outcomes were analyzed with regression analyses. Results: We observed peaks in the use of certain medications during the acute infection phase, including corticosteroids and antithrombotic agents, with a decrease in the use of renin–angiotensin system inhibitors. Consistently high use of alimentary tract medications was found across all phases. Pre-COVID respiratory medications were associated with fatigue symptoms, while antiinfectives and cardiovascular drugs were linked to fewer persisting long COVID symptom categories. Conclusion: Our findings provide longitudinal, descriptive pharmacotherapy insights and suggest that medication history can be a valuable health status indicator in characterizing patients for personalized disease management strategies, considering the heterogeneous nature of long COVID.