Acanthosis nigricans is a medical sign characterised by brown-to-black, poorly defined, velvety hyperpigmentation of the skin. It is usually found in body folds, such as the posterior and lateral folds of the neck, the armpits, groin, navel, forehead and other areas.
Hyperpigmentation is the darkening of an area of skin or nails caused by increased melanin.
Ochronosis is a syndrome caused by the accumulation of homogentisic acid in connective tissues. The condition was named after the yellowish (ocher-like) discoloration of the tissue seen on microscopic examination. Macroscopically, though, the affected tissues appear bluish-grey because of a light-scattering phenomenon known as the Tyndall effect. The condition is most often associated with alkaptonuria, but can occur from exogenous administration of phenol complexes such as hydroquinone. It was first described by Rudolf Virchow in 1865.
Becker's nevus is a benign skin disorder predominantly affecting males. The nevus can be present at birth, but more often shows up around puberty. It generally first appears as an irregular pigmentation on the torso or upper arm, and gradually enlarges irregularly, becoming thickened and often hairy (hypertrichosis). The nevus is due to an overgrowth of the epidermis, pigment cells (melanocytes), and hair follicles. This form of nevus was first documented in 1948 by American dermatologist Samuel William Becker (1894–1964).
Hailey–Hailey disease (HHD), or familial benign chronic pemphigus or familial benign pemphigus, was originally described by the Hailey brothers in 1939. It is a genetic disorder that causes blisters to form on the skin.
Neonatal-onset multisystem inflammatory disease is a rare genetic periodic fever syndrome which causes uncontrolled inflammation in multiple parts of the body starting in the newborn period. Symptoms include skin rashes, severe arthritis, and chronic meningitis leading to neurologic damage. It is one of the cryopyrin-associated periodic syndromes.
Pigmentation disorders are disturbances of human skin color. There may be a loss or reduction, which may be related to loss of melanocytes or the inability of melanocytes to produce melanin or transport melanosomes correctly.
Erythromelanosis follicularis faciei et colli is an erythematous pigmentary disease involving the follicles, characterized by a reddish-brown, sharply demarcated, symmetrical discoloration involving the preauricular and maxillary regions.
Hemosiderin hyperpigmentation is pigmentation due to deposits of hemosiderin, and occurs in purpura, haemochromatosis, hemorrhagic diseases, and stasis dermatitis.
Galli–Galli disease is a rare inherited condition that has close resemblance clinically to Dowling-Degos' disease, but is histologically distinct, characterized by skin lesions that are 1- to 2-mm slightly keratotic red to dark brown papules which are focally confluent in a reticulate pattern. The disease is also characterized by slowly progressive and disfiguring reticulate hyperpigmentation of the flexures, clinically and histopathologically diagnostic for Dowling-Degos disease but also associated with suprabasal, nondyskeratotic acantholysis.
Titanium metallic discoloration has been reported to have occurred with titanium-containing ointment causing papules on the penis of a patient. Titanium screws used for orthopedic procedures, if they come near the skin, can also causes cutaneous blue-black hyperpigmentation.
Linear and whorled nevoid hypermelanosis is a disorder of pigmentation that develops within a few weeks of birth and progresses for one to two years before stabilizing. There is linear and whorled hyperpigmentation following the lines of Blaschko without preceding bullae or verrucous lesions. It is important to exclude other pigmentary disorders following the Blaschko lines before making a diagnosis of linear and whorled nevoid hypermelanosis. The differential diagnoses include incontinentia pigmenti, linear epidermal nevus, hypomelanosis of Ito and Goltz syndrome. Recently, a case of linear and whorled nevoid hypermelanosis was reported in a Malaysian Chinese girl.
Clouston's hidrotic ectodermal dysplasia is a medical condition caused by mutations in a connexin gene, GJB6 or connexin-30, characterized by scalp hair that is wiry, brittle, and pale. It is often associated with patchy alopecia.
Erythema dyschromicum perstans is an uncommon skin condition with peak age of onset being young adults, but it may also be seen in children or adults of any age. EDP is characterized by hyperpigmented macules that are ash-grey in color and may vary in size and shape. While agents such as certain medications, radiographic contrast, pesticides, infection with parasites, and HIV have been implicated in the occurrence of this disease, the cause of this skin disease remains unknown.
Hutchinson's sign is a clinical sign which may refer to:
X-linked reticulate pigmentary disorder is a rare X-linked genetic condition in which males manifest multiple systemic symptoms and a reticulated mottled brown pigmentation of the skin, which, on biopsy, demonstrated dermal deposits of amyloid. Females usually only have linear streaks of hyperpigmentation.
H syndrome, also known as Histiocytosis-lymphadenopathy plus syndrome or PHID, is a rare genetic condition caused by mutations in the SLC29A3 gene which encode the human equilibrative nucleoside transporter (hENT3) protein.
