Reticular pigmented anomaly of the flexures (also known as "dark dot disease", and "Dowling–Degos' disease") is a fibrous anomaly of the flexures or bending parts of the axillae, neck and inframammary/sternal areas. It is an autosomal-dominant pigmentary disorder that may appear in adolescence or adulthood. This condition is due to mutations in structural/desmosomal proteins found within stratified squamous epithelium.

Dark dot disease is associated with "KRT5".

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.

Some confusion exists between Fleischer rings and Kayser-Fleischer rings. Kayser-Fleischer rings are caused by copper deposits, and are indicative of Wilson's disease, whereas Fleischer rings are caused by iron deposits. One example of a medical condition that can present with Fleischer rings is Keratoconus.

Fleischer rings are pigmented rings in the peripheral cornea, resulting from iron deposition in basal epithelial cells, in the form of hemosiderin. They are usually yellowish to dark-brown, and may be complete or broken.

They are named for Bruno Fleischer.

Fleischer rings are indicative of keratoconus, a degenerative corneal condition that causes the cornea to thin and change to a conic shape.

Granulosis rubra nasi is a rare familial disease of children, occurring on the nose, cheeks, and chin, characterized by diffuse redness, persistent hyperhidrosis, and small dark red papules that disappear on diascopic pressure.

Melasma is thought to be the stimulation of melanocytes (cells in the epidermal layer of skin that produce a pigment called melanin) by the female sex hormones estrogen and progesterone to produce more melanin pigments when the skin is exposed to sun. Women with a light brown skin type who are living in regions with intense sun exposure are particularly susceptible to developing this condition.

Genetic predisposition is also a major factor in determining whether someone will develop melasma.

The incidence of melasma also increases in patients with thyroid disease. It is thought that the overproduction of melanocyte-stimulating hormone (MSH) brought on by stress can cause outbreaks of this condition. Other rare causes of melasma include allergic reaction to medications and cosmetics.

Melasma Suprarenale "(Latin - above the kidneys)" is a symptom of Addison's disease, particularly when caused by pressure or minor injury to the skin, as discovered by Dr. FJJ Schmidt of Rotterdam in 1859.

Frontal Fibrosing Alopecia has been most often reported in post-menopausal women with higher levels of affluence and a negative smoking history. Autoimmune disease is found in 30% of patients.

Periorbital hyperpigmentation is characterized by dark circles around the eyes, which are common, often familial, and frequently found in individuals with dark pigmentation or Mediterranean ancestry. Atopic dermatitis patients may also exhibit periorbital pigmentation (allergic shiners) due to lower eyelid venous stasis, and treatment is ineffective.

Although the pathogenesis of Frontal Fibrosing Alopecia is poorly understood, autoimmune reaction and hormonal factors may play a role.

As Kayser–Fleischer rings do not cause any symptoms, it is common for them to be identified during investigations for other medical conditions. In certain situations, they are actively sought; in that case, the early stages may be detected by slit lamp examination before they become visible to the naked eye.

Kayser–Fleischer rings (KF rings) are dark rings that appear to encircle the iris of the eye. They are due to copper deposition in part of the cornea (Descemet's membrane) as a result of particular liver diseases. They are named after Dr. Bernhard Kayser and Dr. Bruno Fleischer, the German doctors who first described them in 1902 and 1903. Initially thought to be due to the accumulation of silver, they were first demonstrated to contain copper in 1934.

Jalili syndrome is a genetic disorder characterized by the combination of cone-rod dystrophy of the retina and amelogenesis imperfecta. It was characterized in 1988 by Dr. I. K. Jalili and Dr. N. J. D. Smith, following the examination of 29 members of an inbred, Arab family living within the Gaza Strip.

One cause of the White Dot Syndromes as suggested by Gass involves viral or infectious agents. Specifically pertaining to the ‘AZOOR complex,’ Gass has postulated that a virus may enter the retina at the optic head and the infection may spread from one photoreceptor to another. Some unexplained features include the development of more than one disease in the same patient and the majority of cases occurring in females.

According to Becker’s common genetic hypothesis, “unlike mendelian genetic disorders, common autoimmune and inflammatory diseases arise from combinatorial interactions of common non-disease specific loci, disease specific loci, and specific environmental triggers.” An important aspect of this hypothesis pertains to the existence of common non-disease genes that predispose patients to autoimmune diseases. Jampol and Becker insinuate that ‘common susceptibility genes’ are present in patients affected by white dot syndromes. The presence of environmental triggers, such as viral infections, immunizations, and stress, and interactions with other genes contribute to the development of the white dot syndromes. Additionally, Jampol and Becker hypothesize that the predisposing genetic loci can be identified.

Gass points to a lack of evidence in support of the Becker theory. Instead, Gass highlights that although evidence indicates that patients with AZOOR have a greater chance of developing autoimmune diseases, this does not mean that the AZOOR complex of disorders are themselves autoimmune diseases. This is supported by the difficulty in detecting “retinal autoantibodies” in AZOOR patients.

Two other diseases which also present with white dots on the fundus are retinitis punctata albescens and fundus albipunctatus. These diseases are not white dot syndromes, but have much more defined etiology. Retinitis punctata albescens is caused by mutations in RLBP1, the gene for retinaldehyde binding protein 1. In comparison, fundus albipunctatus is caused by mutations in RDH5 gene for an 11-cis-RDH in RPE cells.

Spider angiomas form due to failure of the sphincteric muscle surrounding a cutaneous arteriole. The central red dot is the dilated arteriole and the red "spider legs" are small veins carrying away the freely flowing blood. If momentary pressure is applied, it is possible to see the emptied veins refilling from the centre. No other angiomas show this phenomenon.

The dilation, in turn, is caused by increased estrogen levels in the blood. Many pregnant women, or women using hormonal contraception, have spider angiomas, due to high estrogen levels in their blood. Individuals with significant hepatic disease also show many spider angiomas, as their liver cannot metabolize circulating estrogens, specifically estrone, which derives from the androgen androstenedione. About 33% of patients with cirrhosis have spider angiomas. As such, microhemorrhages may be observed as spider angiomas.

Lavender foal syndrome (LFS), also called coat color dilution lethal (CCDL), is an autosomal recessive genetic disease that affects newborn foals of certain Arabian horse bloodlines. Affected LFS foals have severe neurological abnormalities, cannot stand, and require euthanasia shortly after birth. The popular name originates due to a diluted color of the foals coat, that in some cases appears to have a purple or lavender hue. However, not all foals possess the lavender coat colour, colouring can range from silver to light chestnut to a pale pink. Carrier horses have no clinical signs and DNA testing can determine if a horse carries the gene.

Melanism, meaning a mutation that results in completely dark skin, does not exist in humans. Melanin is the primary determinant of the degree of skin pigmentation and protects the body from harmful ultraviolet radiation. The same ultraviolet radiation is essential for the synthesis of vitamin D in skin, so lighter color of skin - less melanin - is an adaptation for the prehistoric movement of humans away from equatorial regions, as there is less exposure to sunlight at higher latitudes. People from parts of Africa have very dark skin, but this is not melanism.

MEWDS is a self limited disease with excellent visual recovery within 2-10 weeks. However residual symptoms including photopsia may persist for months.

Spider angiomas are asymptomatic and usually resolve spontaneously. This is common in the case of children, although they may take several years to disappear. If the spider angiomas are associated with pregnancy, they may resolve after childbirth. In women taking oral contraceptives, they may resolve after stopping these contraceptives. The spider angiomas associated with liver disease may resolve when liver function increases or when a liver transplant is performed.

For spider angiomas on the face, techniques such as electrodesiccation and laser treatment can be used to remove the lesion. There is a small risk of a scar, although the results are generally good. Spider angiomas can recur after treatment.

The Jalili syndrome is caused by different mutations all with a linkage at the achromatopsia locus 2q11 on the metal transporter gene, CNNM4. Sequence analysis of this gene within Jalili syndrome sufferers has identified homozygosity or compound heterozygosity for several different mutations in the CNNM4 gene.

The symptoms of melasma are dark, irregular well demarcated hyperpigmented macules to patches commonly found on the upper cheek, nose, lips, upper lip, and forehead. These patches often develop gradually over time. Melasma does not cause any other symptoms beyond the cosmetic discoloration. Melasma is also common in pre-menopausal women. It is thought to be enhanced by surges in certain hormones.

Multiple evanescent white dot syndrome (MEWDS) is an uncommon inflammatory condition of the retina that typically affects otherwise healthy young females in the second to fourth decades of life.

The typical patient with MEWDS is a healthy middle aged female age 15-50. There is a gender disparity as women are affected with MEWDS four times more often than men. Roughly 30% of patients have experienced an associated viral prodrome. Patients present with acute, painless, unilateral change in vision.

Spinal osteoarthropathy is genetic, carried by parents and passed onto their offspring. Another known cause of this disease is a vitamin B12 deficiency in the reptile, which can be treated by injecting its food with a vitamin supplement.

Lavender foal syndrome is thought to be created by an autosomal recessive gene. When a horse is heterozygous for the gene, it is a carrier, but healthy and has no clinical signs of the condition. If two carriers are bred together, however, classic Mendelian genetics indicate a 25% chance of any given mating producing a homozygous foal, hence affected by the disease. Carrier horses can be bred and produce non-affected foals, as long as they are bred with a non-carrier for the LFS gene. It is hypothesized, though untested, that LFS may be linked to another genetic disease that affects Egyptian-related Arabians, juvenile epilepsy. This theory has been raised because of a small number of horses that have produced both LFS and epileptic foals.

LFS is one of six genetic diseases known to affect horses of Arabian bloodlines. Genetic diseases affect other horse breeds, including different coat color-based lethals, such as lethal white syndrome. In addition, the color white in horses, when created by certain alleles of "dominant white" (W), may possibly be fatal if homozygous.

White dot syndromes are inflammatory diseases characterized by the presence of white dots on the fundus, the interior surface of the eye. The majority of individuals affected with white dot syndromes are younger than fifty years of age. Some symptoms include blurred vision and visual field loss. There are many theories for the etiology of white dot syndromes including infectious, viral, genetics and autoimmune.

Classically recognized white dot syndromes include:

- Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)

- Birdshot chorioretinopathy

- Multiple evanescent white dot syndrome (MEWDS)

- Acute zonal occult outer retinopathy (AZOOR)

- Multifocal choroiditis and panuveitis (MCP)

- Punctate inner choroiditis (PIC)

- Serpiginous choroiditis

Vision improves in almost all cases. In rare cases, a patient may suffer permanent visual loss associated with lesions on their optic nerve.

Rarely, coexisting vasculitis may cause neurological complications. These occurrences can start with mild headaches that steadily worsen in pain and onset, and can include attacks of dysesthesia. This type of deterioration happens usually if the lesions involve the fovea.