Darier disease

Darier disease is an autosomal-dominant disorder of keratinization characterized by delayed onset and highly variable progressive skin manifestations that are occasionally associated with neuropsychiatric manifestation.

The disease usually begins between the ages of 6 and 20 years, with a peak onset during puberty. The rash is typically exacerbated by heat and light.

The primary lesions are keratotic red to brown papules, which develop in a “seborrheic” distribution involving the trunk, scalp margins, face and neck.

In Darier disease the nails often show distal notches, subungual hyperkeratosis and red and white longitudinal bands. Marked nail dystrophies may evolve over time. In oral mucosa, white grouped papules are found, initially on the palate or buccal mucosa but they may become very widespread.

Darier disease is caused by mutations in ATP2A2, a gene on chromosome 12 that encodes a calcium pump of the endoplasmic reticulum, facilitating intracellular calcium homeostasis.
Darier disease

Infectious disease of leprosy

Leprosy is an infectious disease caused by bacteria called Mycobacterium leprae that hide in the coolest areas of the body. The Mycobacterium leprae bacillus, also known as Hansen’s bacillus, ranges from 2 to 7 micrometers (1 micrometer = 1/1000 of a millimeter) in length and 0.3 to 0.4 micrometers in width.

Leprosy can strike at any age most often afflicts those between ten and twenty years of age. Untreated leprosy can lead to severe complications, including blindness and disfigurement, but leprosy can be cured with proper medication.

The simplest form of leprosy, the indeterminate type, primarily affects the skin, causing swollen, reddish patches while the body’s immune system tries to fight off the disease.

Mycobacterium

Leprosy can affect the nerves that control the sweat glands and the sebaceous, glands, which are the glands that keep skin moist. This can cause hair loss, especially loss of eyebrows. Drying skin cracks, causing open sores that can become infected.

The disease causes a lightening (or darkening) of the skin, with a loss of feeling and sweating. Some types of the disease produce a rash of bumps or nodules on the skin.

Patient can no longer sense pain, the body looses the automatic withdrawal reflex that protects against trauma from sharp or hot objects, leading to extensive scarring or even loss of fingers and toes.
Infectious disease of leprosy