Acanthosis nigricans (AN) is a skin condition characterized by hyperpigmented, velvety lesions in skin folds. It is often associated with systemic conditions such as type 2 diabetes, obesity, and polycystic ovary syndrome. It can also be linked to neoplastic processes, particularly in the digestive tract, and is not related to type 1 diabetes. This case report describes a 11-year-old patient with congenital hyperpigmentation that has progressed over time, affecting multiple body areas. The patient exhibits distinctive facial features, eczematous lesions on the nostrils, and a pachydermiform skin appearance. Radiological findings include craniosynostosis, leading to intracranial pressure. The patient also has dental issues. Histopathology is suggested for educational purposes. AN is classified into various types, including benign, obesity-related, syndromic, malignant, and drug-induced. It is often diagnosed clinically, with symmetric, hyperpigmented, hyperkeratotic, and verrucous lesions. AN can coexist with other conditions like Baker's nevus. The condition is associated with insulin resistance and hyperandrogenism. Treatment involves addressing underlying causes, such as weight loss, insulin resistance, or tumor removal. AN is a significant clinical finding that may indicate systemic conditions and requires thorough evaluation. The case highlights the importance of considering AN in patients with skin changes, especially in the context of systemic diseases.Acanthosis nigricans (AN) is a skin condition characterized by hyperpigmented, velvety lesions in skin folds. It is often associated with systemic conditions such as type 2 diabetes, obesity, and polycystic ovary syndrome. It can also be linked to neoplastic processes, particularly in the digestive tract, and is not related to type 1 diabetes. This case report describes a 11-year-old patient with congenital hyperpigmentation that has progressed over time, affecting multiple body areas. The patient exhibits distinctive facial features, eczematous lesions on the nostrils, and a pachydermiform skin appearance. Radiological findings include craniosynostosis, leading to intracranial pressure. The patient also has dental issues. Histopathology is suggested for educational purposes. AN is classified into various types, including benign, obesity-related, syndromic, malignant, and drug-induced. It is often diagnosed clinically, with symmetric, hyperpigmented, hyperkeratotic, and verrucous lesions. AN can coexist with other conditions like Baker's nevus. The condition is associated with insulin resistance and hyperandrogenism. Treatment involves addressing underlying causes, such as weight loss, insulin resistance, or tumor removal. AN is a significant clinical finding that may indicate systemic conditions and requires thorough evaluation. The case highlights the importance of considering AN in patients with skin changes, especially in the context of systemic diseases.