Akademik Veri Yönetim Sistemi
34th EADV Congress, Paris, Fransa, 17 - 20 Eylül 2025, cilt.17, ss.158-159, (Özet Bildiri)
Introduction & Objectives: Pachyonychia congenita is a rare autosomal dominant disorder characterized by severe, painful palmoplantar keratoderma, nail dystrophy, and oral leukokeratosis. Its etiology is attributed to mutations in keratin genes. Materials & Methods: Herein, we report an infant presenting with nail dystrophy who was diagnosed with pachyonychia congenita based on clinical and genetic findings, including a de novo heterozygous variant in the KRT6A gene. Results: A male infant born at 36+6 weeks of gestation via spontaneous vaginal delivery to a 38-year-old mother presented with thickened, yellow discoloration of fingernails and toenails. Progressive nail changes were noted over the following months, prompting further evaluation in collaboration with the dermatology department. His medical history included hospitalization in the neonatal intensive care unit with an early diagnosis of sepsis. The patient had an unremarkable family history. Dermatological examination revealed discolored, thickened, and wedge-shaped fingernails and toenails. Leukokeratotic plaques were observed on the dorsum of the tongue and hard palate mucosa, first noted during the third month of life. Based on nails and oral mucosa findings, a preliminary diagnosis of congenital pachyonychia was considered. After obtaining informed consent from his parents, genomic DNA was extracted from peripheral blood. Whole exome sequencing (Qiagen, Hilden, Germany) detected a de novo heterozygous variant in the KRT6A gene [NM_005554.4:c.513C>A (p.N171K)]. Segregation analysis confirmed that both biological parents were homozygous for the wild-type allele, verifying the variant as de novo. The diagnosis of pachyonychia congenita was confirmed by the identification of a pathogenic genetic mutation. The patient was treated with 10% urea cream, resulting in visible nail smoothening during follow-up. Oral hygiene was also recommended. Conclusion: Pachyonychia congenita typically manifests within the first three years of life with a triad of nail dystrophy, plantar pain, and plantar keratoderma. Although mutations in the KRT6A, KRT6B, KRT6C, KRT16, and KRT17 genes are implicated in its pathogenesis, KRT6A mutations, which encodes keratins expressed in the palmoplantar epidermis, nails, and mucosa, are the most frequently encountered. Among KRT6A mutations, toenail dystrophy is the most common finding, tends to be more severe, and has a significantly increased likelihood of involvement of all toenails. Subungual thickening leading to a V-shaped curvature of both fingernails and toenails is characteristic. Plantar keratoderma appears with onset of walking, typically at the heels, and plantar pain leads to walking difficulties. Oral leukokeratosis generally appears by the third week of life, most commonly affecting the tongue, and may cause snoring. Other frequent findings include follicular hyperkeratosis, hyperhidrosis, and cysts. Diagnosis relies on clinical, genetic, and family history assessments. In this case report, we presented an infant with nail dystrophy who was diagnosed with pachyonychia congenita due to a KRT6A mutation. This case highlights the importance of a detailed dermatological examination, including the oral mucosa, in infants presenting with thick yellow nails. Pachyonychia congenita should be considered among the differential diagnoses, even in the absence of a family history, due to the possibility of de novo mutations.