Reticulate acropigmentation of Kitamura

Reticulate acropigmentation of Kitamura (RAK) is a rare inherited skin disorder characterized by a distinctive pattern of reticulate (net-like) hyperpigmented macules that primarily affect the dorsal surfaces of the hands and feet (acral areas). The condition was first described by the Japanese dermatologist Kitamura in 1943. It is also known as reticulate acropigmentation of Kitamura or Kitamura disease. The pigmented macules are typically small, slightly depressed, and arranged in a reticular pattern. Additional features may include pits or breaks in the epidermal ridges of the palms and soles (interrupted dermatoglyphics), which is considered a hallmark finding. Some patients may also develop pigmented macules on other body areas over time. The condition is caused by heterozygous loss-of-function mutations in the ADAM10 gene (a disintegrin and metalloproteinase domain 10), located on chromosome 15q21.3. ADAM10 plays a role in various cell signaling pathways, including Notch signaling, which is important for skin pigmentation and epidermal homeostasis. The onset of pigmentary changes typically begins in childhood, often in the first or second decade of life, and tends to progress slowly over time. The condition is generally benign and does not affect internal organs or overall health, though the cosmetic appearance can cause significant psychosocial distress. There is currently no curative treatment for reticulate acropigmentation of Kitamura. Management is primarily supportive and cosmetic. Sun protection is generally recommended to minimize further pigmentation. Topical depigmenting agents such as hydroquinone or retinoids have been tried with limited success. Laser therapies have been explored in some cases but results are variable and recurrence of pigmentation is common. Genetic counseling is recommended for affected individuals and their families given the autosomal dominant inheritance pattern.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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