Clinical issue <p>Lymphatic malformations (LM) are congenital abnormalities of the lymphatic system and occur with an incidence of 1:6000–1:16,000 live births. Simple LMs manifest as soft-elastic space-occupying lesions, whereas complex LMs affect several organ systems and can lead to chylous effusions due to lymph leakage. In addition, LM can occur together with other vascular malformations or as part of overgrowth syndromes. Primary lymphedema is a special subgroup of LMs, which can first be clinically manifested in advanced age.</p> Diagnostics <p>Imaging procedures are of great importance in the diagnostics of LM, in particular magnetic resonance imaging (MRI) and MR lymphangiography. Additionally, genetic testing should be carried out to detect possible comorbidities at an early stage and to enable targeted treatment.</p> Treatment strategies <p>The decision for treatment depends on the underlying LM as well as the extent and localization. Medicinal treatment is possible with the mTOR inhibitor sirolimus and with propranolol via the vascular endothelial growth factor (VEGF)-Ras-MAPK pathway, also as a combined treatment, Depending on the results of genetic analyses, targeted treatment with alpelisib/trametinib is also an option. Moreover, surgical and radiological interventional approaches can be used, depending on the underlying findings.</p> Practical recommendations <p>Patients with LM should be referred to an expert center to enable an early diagnosis and treatment in an interdisciplinary team. Together with the clinical and genetic findings MRI and MR lymphangiography enable the evaluation of interventional and surgical treatment options.</p>