Related Research Articles
Lichen simplex chronicus (LSC) is a skin disorder characterized by chronic itching and scratching. The constant scratching causes thick, leathery, darkened, (lichenified) skin. This condition is associated with many factors, including the scratch-itch cycle, psychological stressors, and atopy. LSC is more common between ages 35 and 50 and is seen approximately twice as often in women compared to men.
Lichen planus (LP) is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, and is only named that because it looks like one. It is characterized by polygonal, flat-topped, violaceous papules and plaques with overlying, reticulated, fine white scale, commonly affecting dorsal hands, flexural wrists and forearms, trunk, anterior lower legs and oral mucosa. Although there is a broad clinical range of LP manifestations, the skin and oral cavity remain as the major sites of involvement. The cause is unknown, but it is thought to be the result of an autoimmune process with an unknown initial trigger. There is no cure, but many different medications and procedures have been used in efforts to control the symptoms.
Lichen sclerosus (LS) is a chronic, inflammatory skin disease of unknown cause which can affect any body part of any person but has a strong preference for the genitals and is also known as balanitis xerotica obliterans (BXO) when it affects the penis. Lichen sclerosus is not contagious. There is a well-documented increase of skin cancer risk in LS, potentially improvable with treatment. LS in adult age is normally incurable, but improvable with treatment, and often gets progressively worse.
A cortex is an outer layer of a stem or root in a plant, lying below the epidermis but outside the vascular bundles. It is also the surface layer or "skin" of the nonfruiting part of the body of some lichens.
A precancerous condition is a condition or lesion involving abnormal cells which are associated with an increased risk of developing into cancer. Clinically, precancerous conditions encompass a variety of conditions or lesions with an increased risk of developing into cancer. Some of the most common precancerous conditions include certain colon polyps, which can progress into colon cancer, monoclonal gammopathy of undetermined significance, which can progress into multiple myeloma or myelodysplastic syndrome. and cervical dysplasia, which can progress into cervical cancer. Pathologically, precancerous lesions can range from benign neoplasias, which are tumors which do not invade neighboring normal tissues or spread to distant organs, to dysplasia, which involves collections of abnormal cells which in some cases have an increased risk of progressing to anaplasia and invasive cancer. Sometimes the term "precancer" is also used for carcinoma in situ, which is a noninvasive cancer that has not progressed to an aggressive, invasive stage. As with other precancerous conditions, not all carcinoma in situ will progress to invasive disease.
Prurigo nodularis (PN), also known as nodular prurigo, is a skin disease characterised by pruritic (itchy) nodules which usually appear on the arms or legs. Patients often present with multiple excoriated lesions caused by scratching. PN is also known as Hyde prurigo nodularis, Picker's nodules, atypical nodular form of neurodermatitis circumscripta, lichen corneus obtusus.
Lichen spinulosus is a rare skin disorder characterized by follicular keratotic papules that are grouped into large patches. It is a variant of keratosis pilaris named for its resemblance to a patch of lichen.
The Koebner phenomenon or Köbner phenomenon, also called the Koebner response or the isomorphic response, attributed to Heinrich Köbner, is the appearance of skin lesions on lines of trauma. The Koebner phenomenon may result from either a linear exposure or irritation. Conditions demonstrating linear lesions after a linear exposure to a causative agent include: molluscum contagiosum, warts and toxicodendron dermatitis. Warts and molluscum contagiosum lesions can be spread in linear patterns by self-scratching ("auto-inoculation"). Toxicodendron dermatitis lesions are often linear from brushing up against the plant. Causes of the Koebner phenomenon that are secondary to scratching rather than an infective or chemical cause include vitiligo, psoriasis, lichen planus, lichen nitidus, pityriasis rubra pilaris, and keratosis follicularis.
Lichen nitidus is a chronic inflammatory disease of unknown cause characterized by 1–2 mm, discrete and uniform, shiny, flat-topped, pale flesh-colored or reddish-brown papules that may appear as hypopigmented against dark skin. Occasionally, minimal scaling is present or can be induced by rubbing the surface of the papules. The disease usually affects children and young adults and is painless and usually nonpruritic, although protracted itching may occur in some cases. It is sometimes referred to by dermatologists as "mini lichen planus".
An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughing out of inflamed necrotic tissue." Common forms of ulcers recognized in medicine include:
Lichen striatus is a rare skin condition that is seen primarily in children, most frequently appearing ages 5–15. It consists of a self-limiting eruption of small, scaly papules.
Lichen myxedematosus is a group of cutaneous disorders considered mucinoses. Conditions included in this group are:
Localized lichen myxedematosus is a group of skin condition caused by fibroblasts producing abnormally large amounts of mucopolysaccharides, a disease for which there is no treatment.
Discrete papular lichen myxedematosus is a skin condition caused by fibroblasts producing abnormally large amounts of mucopolysaccharides characterized by the occurrence of waxy, flesh-colored papules.
Self-healing juvenile cutaneous mucinosis is a skin condition caused by fibroblasts producing abnormally large amounts of mucopolysaccharides, and is characterized by the sudden onset of skin lesions and polyarthritis.
Atypical tuberous myxedema, also known as Jadassohn–Dosseker syndrome, is thought to represent a pure nodular variant of lichen myxedematosus.
Nodular lichen myxedematosus is a cutaneous condition characterized by multiple nodules on the limbs and trunk, with a mild or absent papular component.
Neuropathia mucinosa cutanea is a cutaneous condition characterized by livedo reticularis on the legs and hyperesthesia.
Terete is a term used in botany to describe a cross section that is circular, or like a distorted circle, with a single surface wrapping around it. This is usually contrasted with cross-sections that are flattened, with a distinct upper surface that is different from the lower surface. The cross-section of a branch in a tree is somewhat round, so the branch is terete. The cross section of a normal leaf has an upper surface, and a lower surface, so the leaf is not terete. However, the fleshy leaves of succulents are sometimes terete. Fruticose lichens are terete, with a roughly circular cross section and a single wrap-around skin-like surface called the cortex, compared to foliose lichens and crustose lichens, which have a flattened cross section with an upper surface that is distinct from the lower surface.
References
- ↑ RESERVED, INSERM US14-- ALL RIGHTS. "Orphanet: Atypical lichen myxedematosus". www.orpha.net. Retrieved 18 April 2019.
- ↑ James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 978-0-7216-2921-6.
