Somatic KRAS mutation in an infant with linear nevus sebaceous syndrome associated with lymphatic malformations

RATIONALE Linear nevus sebaceous syndrome (LNSS) is a rare neurocutaneous syndrome, characterized by nevus sebaceous,central nervous system (CNS), ocular and skeletal abnormalities. The present study describes KRAS somatic mosaic mutation in a case of LNSS with lymphatic malformations (LMs). PATIENT CONCERNS A 4-month-old female with a clinical diagnosis of LNSS presented with infantile spasms, mental retardation, skull dysplasia, ocular abnormalities, congenital atrial septal defect, and LMs. DIAGNOSIS Cervical ultrasonography revealed a 4.6 × 4.6 × 2.2cm no echo packet with clear boundary in the subcutaneous tissues of the right neck. The neck MRI indicated a cyst in the subcutaneous tissues of the right neck. Whole-exome sequencing revealed a low-level heterozygous mutation of the KRAS gene (c.35C > T; p.G12D, 19%) in the skin lesion sample. This mutation was not present in the blood samples of the patient and her parents. INTERVENTIONS The patient received sclerotherapy with paicibanil (OK-432) injection for the cyst. OUTCOMES Following 1 year of treatment, the patient exhibited fewer seizures. The mental and motor development was significantly improved. The patient can currently walk with assistance and speak simple words. LESSONS LNSS is a rare, congenital neurocutaneous syndrome consisting of a spectrum of abnormalities involving the skin, central nervous system, eyes, LMs and other systems. LNSS can be caused by postzygotic somatic mutation in the RAS family of genes. Multidisciplinary evaluation and treatment is needed.