Disease Definitions

Acanthocephaliasis 🔎

Acanthocephaliasis is an infectious disease caused by parasitic acanthocephala worms, commonly known as hairworms or scabworms. It affects various animals and humans, causing symptoms like itching, pain, and sometimes neurological issues due to the worms' attachment to skin or internal organs.

Acne inversa see Hidradenitis suppurativa 🔎

Acne inversa is a condition where acne occurs in the deeper skin layers (subcutaneous tissue) rather than on the surface, typically under hair follicles or pores. Hidradenitis suppurativa is a chronic inflammatory skin disease characterized by painful, pus-filled lumps and abscesses in areas where hair follicles converge, often affecting the armpits and groin region.

Acneiform nevus see Nevus comedonicus 🔎

Acneiform nevus: A type of skin lesion characterized by small, dome-shaped bumps or pustules, often found on the face; it resembles acne but is usually less inflammatory and more comedone-like. Nevus comedonicus: A non-cancerous skin growth consisting of a small, flesh-colored or slightly darker spot with a smooth surface, typically found in areas with oily skin like the T-zone (forehead, nose, chin). It appears as a comedone, which is an clogged hair follicle.

Adapalene 🔎

Adapalene is an organic compound with the chemical formula C₁₄H₁₆. It's a colorless liquid or solid used in cosmetics and pharmaceuticals as a UV filter, skin lightener, and hair dye fixative.

Aland island eye disease see Forsius-Eriksson ocular albinism 🔎

Aland Island Eye Disease (ASED) is a rare inherited condition characterized by congenital absence or partial absence of the eye's iris and eyelid structures, often resulting in vision problems. Forsius-Eriksson Ocular Albinism (FEAOA) is an autosomal recessive genetic disorder that causes reduced or absent pigmentation of the eyes, skin, hair, and mucous membranes, leading to light sensitivity and vision issues.

Albinism 🔎

Albinism is a genetic condition characterized by the absence or reduced production of melanin pigment in the skin, hair, and eyes, resulting in light-colored skin, hair, and eyes. It affects various body parts differently, leading to symptoms like vision problems and sensitivity to sunlight.

Albinoidism, oculocutaneous, autosomal dominant 🔎

Albinoidism is a group of rare genetic disorders characterized by reduced or absent melanin production in the skin, hair, and eyes. Oculocutaneous refers to conditions affecting both the eye (ocul) and skin (cutaneous) areas. Autosomal dominant means that only one copy of the altered gene in each cell is sufficient for the disorder to manifest; if one parent has albinoidism, there's a 50% chance their child will inherit it.

Alopecia areata 🔎

Alopecia areata is an autoimmune disorder characterized by patchy hair loss on the scalp and sometimes other areas of the body. It causes the immune system to attack hair follicles, leading to bald patches or complete hair loss in affected individuals.

Alopecia cicatrisata see Pseudopelade of Brocq 🔎

Alopecia cicatrisata is a type of hair loss characterized by scar-like patches on the scalp, resembling pseudopelade of Brocq (a type of skin abscess). Pseudopelade of Brocq is an inflammatory condition that causes pustules and nodular lesions to form on the skin.

Alopecia follicularis see Folliculitis decalvans 🔎

Alopecia follicularis (Folliculitis decalvans) is a rare autoimmune condition causing hair loss on the scalp and sometimes other areas, characterized by inflamed hair follicles that appear scarred or empty. It resembles a form of alopecia areata but differs in its chronic nature and involvement of the skin's hair follicles.

Alopecia circumscripta see Alopecia areata 🔎

Alopecia circumscripta is a type of hair loss characterized by round, well-defined patches of hair loss on the scalp, often occurring in clusters or along specific lines (circumscriptions). It's considered a form of alopecia areata, which involves smaller, irregular patches of hair loss throughout the body.

Alopecia 🔎

Alopecia is a medical condition characterized by hair loss from the scalp or other areas of the body. It can be caused by various factors like genetics, autoimmune diseases, infections, or stress.

Alopecia linearis frontalis see Traction alopecia 🔎

Alopecia linearis frontalis is a type of traction alopecia characterized by hair loss that occurs along the scalp in a linear (straight) pattern, typically starting at the forehead and moving downwards. It results from tension or pulling on the hair follicles due to braiding, tight hairstyles, or other forms of hair stress.

Alopecia mucinosa 🔎

Alopecia mucinosa is a rare hair loss condition characterized by the presence of mucin in the hair follicles, leading to hair loss and sometimes scaling or crusting of the scalp. It results from abnormal accumulation of mucin within the hair follicle's lining.

Alopecia universalis congenita see Total congenital alopecia 🔎

Alopecia Universalis Congenita (AUC) is a rare genetic hair loss condition present at birth where all body hair disappears completely due to the absence of hair follicles. It's also known as total congenital alopecia.

Amelanotic skin see Hypopigmentation 🔎

Amelanotic skin refers to skin that lacks melanin pigment, resulting in a pale or white appearance due to reduced or absent dark pigmentation in hair, eyes, and skin. Hypopigmentation is a broader term describing any condition where there is less than normal pigmentation in the body's tissues, including the skin. Amelanotic skin is specifically characterized by the absence of melanin.

Amish brittle hair syndrome see Hair-brain syndrome 🔎

Amish Brittle Hair Syndrome (ABHS) is a rare genetic disorder characterized by the progressive loss of body and scalp hair in individuals of the Amish ethnicity, often accompanied by neurological symptoms. It resembles Hair-Brain Syndrome (HBS), which refers to a group of symptoms affecting both the nervous system and hair growth, though ABHS has specific genetic and cultural associations.

Anagen effluvium 🔎

Anagen effluvium is a condition characterized by the sudden and dramatic shedding of hair follicles during the growth phase (anagen) of hair, often due to chemotherapy or radiation therapy, resulting in a significant amount of loose hair falling out.

Anabolic steroids see Androgenic steroids 🔎

Anabolic steroids are synthetic derivatives of testosterone that promote muscle growth and strength by increasing protein synthesis in cells. Androgenic steroids, on the other hand, are primarily associated with hair growth and male characteristics; they have more potent effects on the development of male secondary sexual characteristics than anabolic steroids.

Androgenic alopecia see Male pattern baldness 🔎

Androgenic alopecia is a genetic hair loss condition characterized by the progressive thinning of hair, typically following a male or female pattern, leading to male-pattern baldness in men and female-pattern baldness in women. It's caused by dihydrotestosterone (DHT), a byproduct of testosterone, which affects hair follicles.