Familiar cylindromatosis in a Colombian family caused by a mutation in CYLD.

Introduction: The CYLD cutaneous syndrome is characterised by the appearance of multiple skin tumours, including cylindromas, spiradenomas, trichoepitheliomas and basal cell adenomas of the salivary gland and less frequently pulmonary cylindromas. The lesions appear in the second decade of life, typically present as single lesions, located mainly on the face and head and progressively increase in number, potentially affecting the torso, groin and axillae. Although lesions can affect both men and women, a higher frequency of affected women has been described. Case presentation: CYLD cutaneous syndrome is caused by pathogenic variants in the CYLD gene, following an autosomal dominant inheritance pattern. We present the first Colombian case of a family affected by CYLD cutaneous syndrome, spanning three generations and characterised by early onset of skin lesions. This syndrome was molecularly confirmed by next-generation sequencing (NGS), reveling a heterozygous frameshift variant in the CYLD gene, specifically the type NM_015247.2 c.2291_2295delAACTA p.Lys764Ilefs*2, which was subsequently confirmed by Sanger sequencing. Conclusion: Understanding the complex interplay of genetic, epigenetic and environmental factors in the malignant transformation of cylindroma to squamous eccrine ductal carcinoma is crucial for developing targeted therapies and improving patient outcomes. Key messages: The CYLD cutaneous syndrome in a Colombian family.