D2I2.
congenital

Lymphangioma

malformations (LMs) are , slow-flow malformations of the lymphatic system characterized by abnormally lymphatic that do not connect properly to the normal lymphatic circulation. These malformations represent developmental anomalies that occur during embryonic lymphatic system formation and are primarily caused by somatic activating in the PIK3CA gene, found in approximately 75-80% of cases.

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Plain-language summary adapted from Wikipedia. Not medical advice.