Hypertrichosis and Hirsutism
Abstract Hypertrichosis is defined as an excessive growth of hairs anywhere on the body. They are often terminal pigmented hairs but can be vellus or lanugo hairs. Hypertrichosis is frequently…
Ichthyoses, Erythrokeratodermas, and Related Disorders
Abstract This chapter describes the clinical features, etiologies, evaluation, and management of ichthyoses and erythrokeratodermas. Both groups represent disorders of cornification in which abnormal differentiation and desquamation of the epidermis…
Neurofibromatosis and Tuberous Sclerosis Complex
Abstract Neurofibromatosis type 1 (NF1) and tuberous sclerosis complex (TSC) are autosomal dominant neurocutaneous disorders characterized by hamartomas and tumors in the skin, eye, central nervous system, and other organs….
Mosaicism and Linear Lesions
Abstract The term “mosaic” refers to individuals composed of cells with different genotypes that are derived from a genetically homogeneous zygote. Mosaicism can be functional (epigenetic) as in lyonization as…
Melanocyte Biology
Abstract The major determinant of normal skin color is the activity of melanocytes, i.e. the quantity and quality of pigment production, not the density of melanocytes. Melanocytes contain a unique…
Other Genodermatoses
Abstract This section focuses on genetic tumor predisposition syndromes that have characteristic mucocutaneous manifestations. Recognition of these skin findings facilitates diagnosis and surveillance for associated extracutaneous malignancies and endocrine abnormalities….
Palmoplantar Keratodermas
Abstract Palmoplantar keratoderma (PPK) represents a heterogeneous group of hereditary and acquired disorders of cornification characterized by hyperkeratosis of the skin on the palms and soles. Inherited PPK may occur…
Biology of Hair and Nails
Abstract The hair and nails develop through evolutionarily conserved mechanisms. They have a range of shared features, as both represent adnexal structures with specialized keratin constituents characterized by low water…
Primary Immunodeficiencies
Abstract Primary immunodeficiencies represent a heterogeneous group of disorders characterized by increased susceptibility to infection. Many of these conditions have additional manifestations involving autoimmunity, allergy, lymphoproliferation, and risk of malignancy….
Genetic Basis of Cutaneous Diseases
Abstract Advances in molecular technology have led to elucidation of the genetic bases of many single-gene inherited and mosaic skin disorders, greatly improving our understanding of these conditions. Genotype–phenotype correlations…
