List Of Cutaneous (Skin) Conditions - Congenital Anomalies
There are many conditions of or affecting the human integumentary system—the organ system that covers the entire surface of the body and is composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. There are two main types of human skin: glabrous skin, the non-hairy skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, there are hairs in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.
The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers via diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and the Merkel cell. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; it takes about two weeks for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.
The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary and reticular dermis. The superficial papillary dermis interdigitates with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and extrafibrillar matrix (previously called ground substance). Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.
The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.
Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described.
Classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), etiology (skin conditions resulting from physical factors), and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and colour (red, blue, brown, black, white, yellow). The diagnosis of a many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data.
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Diseases – Cutaneous (Skin) Diseases – Congenital Anomalies
Cutaneous congenital anomalies are a diverse group of disorders that result from faulty morphogenesis, the biological process that forms the shape of a human body.
- Accessory nail of the fifth toe
- Accessory tragus (Ear tag, Preauricular appendage, Preauricular tag)
- Amniotic band syndrome (ADAM complex, Amniotic band sequence, Congenital constriction bands, Pseudoainhum)
- Aplasia cutis congenita (Cutis aplasia, Congenital absence of skin, Congenital scars)
- Arteriovenous fistula
- Benign neonatal hemangiomatosis
- Branchial cyst (Branchial cleft cyst)
- Bronchogenic cyst
- Capillary hemangioma (Infantile hemangioma, Nevus maternus, Strawberry hemangioma Strawberry nevus)
- Cavernous venous malformation
- Congenital cartilaginous rest of the neck (Cervical accessory tragus, Wattle)
- Congenital erosive and vesicular dermatosis
- Congenital hypertrophy of the lateral fold of the hallux
- Congenital lip pit (Congenital sinus of the lower lip, Lip sinus, Midline sinus of the upper lip)
- Congenital malformations of the dermatoglyphs
- Congenital smooth muscle hamartoma
- Cystic lymphatic malformation
- Dermoid cyst
- Diffuse neonatal hemangiomatosis
- Encephalocele
- Hutchinson's teeth
- Intrauterine epidermal necrosis
- Limb–mammary syndrome
- Lowry–MacLean syndrome
- Macrocheilia
- Macrocystic lymphatic malformation
- Malignant pilomatricoma (Pilomatrical carcinoma, Pilomatrix carcinoma)
- Maternal autoimmune bullous disease
- Median raphe cyst
- Melanotic neuroectodermal tumor of infancy
- Membranous aplasia cutis
- Microcystic lymphatic malformation
- Midline cervical cleft
- Mongolian spot (Congenital dermal melanocytosis, Dermal melanocytosis)
- Mulberry molar
- Nager acrofacial dysostosis
- Nasal glioma (Brain-like heterotopia, Cephalic brain-like heterotopia, Glial hamartoma, Heterotopic neuroglial tissue, Nasal cerebral heterotopia, Nasal heterotopic brain tissue)
- Nasolacrimal duct cyst
- Nevus psiloliparus
- Non-involuting congenital hemangioma
- Omphalomesenteric duct cyst (Omphalomesenteric duct remnant, Vitelline cyst)
- Pilomatricoma (Calcifying epithelioma of Malherbe, Malherbe calcifying epithelioma, Pilomatrixoma)
- Poland anomaly
- Posterior fossa malformations–hemangiomas–arterial anomalies–cardiac defects–eye abnormalities–sternal cleft and supraumbilical raphe syndrome (PHACE association, PHACES syndrome)
- Preauricular sinus and cyst (Ear pit, Congenital auricular fistula, Congenital preauricular fistula, Ear pit, Preauricular cyst)
- Rapidly involuting congenital hemangioma (Congenital non-progressive hemangioma)
- Rosenthal–Kloepfer syndrome
- Rudimentary supernumerary digit (Rudimentary polydactyly)
- Sinus pericranii
- Skin dimple (Skin fossa)
- Superficial lymphatic malformation (Lymphangioma circumscriptum)
- Supernumerary nipple (Accessory nipple, Pseudomamma)
- Thyroglossal duct cyst
- Verrucous vascular malformation (Angiokeratoma circumscriptum naeviforme)
