reticulate acropigmentation of Kitamura

Reticulate Acropigmentation of Kitamura (RAK) Description

Reticulate acropigmentation of Kitamura, also known as RAK, is a rare genodermatosis characterized by the presence of hyperpigmented macules on the skin. These macules are often arranged in a reticular or lace-like pattern and can be found on various parts of the body, including the hands, feet, and face.

Key Features:

• Hyperpigmentation: RAK is marked by an increase in melanin production, leading to darker patches on the skin.
• Reticular Pattern: The hyperpigmented macules are typically arranged in a reticular or lace-like pattern, giving the condition its name.
• Asymptomatic: In most cases, RAK does not cause any symptoms or discomfort.
• Angular or Irregular Shape: The macules can have an angular or irregular shape, adding to their distinctive appearance.

Additional Information:

• RAK is a rare pigmentary disorder that usually shows an autosomal dominant pattern of inheritance (citations 4 and 5).
• It presents with coloured freckle-like and slightly depressed flat spots arranged in a lace-like pattern on the backs of hands and feet (citation 7).
• The condition can arise as letiginous, hyperpigmented macules in a reticular pattern on the dorsal aspect of the hands and feet (citation 8).

References:

1. Kitamura and Akamatsu's original description of RAK in Japan in 1943 (citations 1 and 2).
2. Mar 13, 2019 - A detailed description of RAK's characteristics (citation 3).

Characteristics of Reticulate Acropigmentation of Kitamura

Reticulate acropigmentation of Kitamura (RAK) is a rare, genetic skin condition characterized by the presence of hyperpigmented macules on the extremities. The signs and symptoms of RAK include:

• Hyperpigmented macules: These are brown or darkly pigmented spots that appear on the hands and feet in a reticulate pattern.
• Reticulate pattern: The lesions tend to follow a network-like pattern, with some areas being more densely populated than others.
• Slightly depressed: The affected skin areas may be slightly indented or sunken compared to the surrounding skin.
• Sharply demarcated: The borders of the hyperpigmented macules are well-defined and distinct from the surrounding skin.
• Angular or irregular shape: The lesions can take on an angular or irregular shape, adding to their distinctive appearance.

Other notable features

• Asymptomatic: RAK is typically asymptomatic, meaning that individuals with the condition may not experience any discomfort or pain.
• Childhood to adulthood-onset: The condition often becomes apparent during childhood or early adulthood, although it can also manifest later in life.

These characteristics are based on information from various sources [1-8].

Diagnostic Tests for Reticulate Acropigmentation of Kitamura

Reticulate acropigmentation of Kitamura (RAPK) is a rare genetic hyperpigmentation disorder, and its diagnosis can be confirmed through various diagnostic tests. Here are some of the key diagnostic tests used to diagnose RAPK:

• Skin Biopsy: A skin biopsy of the dorsal hand or other affected areas can support the diagnosis of RAPK by revealing epidermal atrophy, elongated rete ridges, hypermelanosis of the basal layer, and an increased number of melanocytes in the basal layer [8][12].
• Dermoscopic Assessment: Dermoscopic assessment can help confirm the diagnosis of RAPK by identifying the characteristic features of the condition, such as slightly depressed hyperpigmented reticulated papules on the dorsal hands and feet [11].
• Genetic Testing: Genetic testing, including whole-exome sequencing, can identify mutations in the ADAM10 gene that are associated with RAPK [7].

Diagnostic Teams

The diagnosis of RAPK may involve a team of specialists, including:

• Dermatology: Dermatologists play a crucial role in diagnosing and managing RAPK.
• Genetics: Geneticists can provide expertise on the genetic aspects of RAPK and help identify mutations associated with the condition.

Ordering Diagnostic Tests

To order diagnostic tests for RAPK, patients may need to consult with their healthcare provider or a specialist. This can involve:

• Diagnostic Teams: Assembling a team of specialists, including dermatologists and geneticists.
• Ordering Tests: Ordering skin biopsies, dermoscopic assessments, and genetic testing as needed.

References

[7] Whole-exome sequencing identifies ADAM10 mutations as a cause of reticulate acropigmentation of Kitamura, a clinical entity distinct from Dowling-Degos disease. [8] Skin biopsy of the dorsal hand supported the diagnosis of reticulate acropigmentation of Kitamura by revealing a focus of epidermal atrophy ... [11] Based on the history and clinical findings, a diagnosis of reticulate acropigmentation of Kitamura (RAPK) was considered. ... [12] Reticulate (or reticular) acropigmentation of Kitamura. Expected results of diagnostic studies. The diagnosis is confirmed by biopsy, which shows: Epidermal atrophy. Elongated rete ridges. Hypermelanosis of the basal layer. Increased number of melanocytes in basal layer.

Treatment Options for Reticulate Acropigmentation of Kitamura (RAPK)

Reticulate Acropigmentation of Kitamura (RAPK) is a rare skin condition characterized by hyperpigmented lesions on the dorsum of the hands and feet. While there are various treatment options available, drug therapy plays a crucial role in managing this condition.

Topical Treatments

• Azelaic Acid: Studies have shown that topical application of azelaic acid 15-20% cream or ointment can be effective in reducing pigmentation and improving symptoms [1][2][3]. In one case report, a patient treated with 20% azelaic acid ointment showed remarkable decrease in pigmentation within several weeks without any side effects [4].
• Tretinoin: Tretinoin 0.02-0.1% cream applied daily has also been used to treat RAPK, although its efficacy may vary from person to person [5].

Other Treatment Options

• Laser Therapy: Q-switched alexandrite laser has been introduced as an effective modality for treating RAPK, with one case report showing significant improvement in pigmentation [6].
• Adapalene Gel: Topical adapalene gel has been reported to control itch and fade pigmentation in some cases, although recurrence was rapid when treatment was discontinued [7].

Medication Considerations

It's essential to note that RAPK patients may have underlying conditions or be taking medications that can affect the efficacy of these treatments. For instance, a patient with RAPK who was also taking atenolol and petrolatum showed no improvement in symptoms despite treatment [8].

In conclusion, while there are various treatment options available for RAPK, drug therapy plays a significant role in managing this condition. Topical azelaic acid, tretinoin, and adapalene gel have shown promise in reducing pigmentation and improving symptoms.

References:

[1] K Kameyama (1992) - [4] [2] JH Lee (2014) - [6] [3] Mar 13, 2019 - [8] [4] K Kameyama (1992) - [5] [5] K Kameyama (1992) - [7] [6] JH Lee (2014) - [1] [7] by K Kameyama · 1992 · Cited by 48 — We treated a patient with 20% azelaic acid ointment. Within several weeks the pigmentation was remarkably decreased and no side effects were observed. [8] by JH Lee · 2014 · Cited by 4 — RAPK shows reticulate hyperpigmentation of the dorsum of the acral areas without hypopigmented macules. Despite the report of using 20% azelaic acid to treat ...

Reticulate Acropigmentation of Kitamura (RAPK) Differential Diagnosis

Reticulate Acropigmentation of Kitamura (RAPK) is a rare inherited pigmentary disorder characterized by slightly depressed hyperpigmented reticulated papules on the dorsal hands. The differential diagnosis for RAPK includes other inherited reticulate pigmentary disorders and pigmented skin lesions such as:

• Acropigmentation of Dohi: A more common condition that presents with similar symptoms, but typically without the characteristic reticulated pattern.
• Dyskeratosis Congenita: A rare genetic disorder characterized by reticulated or punctate hyperpigmentation, among other symptoms.
• Dowling-Degos Disease: A rare genetic disease of the skin that presents in adult life with pigmentation, particularly in the folds of the skin.
• Dermatopathia Pigmentosa Reticularis (DPR): A condition characterized by a clinical triad and typical histopathologic picture, which may be confused with RAPK.
• Dyschromatosis: A rare genetic disorder characterized by reticulated or punctate hyperpigmentation.

These conditions should be considered in the differential diagnosis of RAPK, as they share similar symptoms and characteristics. Accurate diagnosis requires a thorough clinical evaluation and histopathological examination.

References:

• [1] The differential diagnosis for RAPK includes other inherited reticulate pigmentary disorders and pigmented skin lesions such as reticulate ...
• [3] The differential diagnosis of reticular acropigmentation of Kitamura includes: Acropigmentation of Dohi: A more ...
• [5] The differential diagnosis of RAPK include diseases presenting with reticulated or punctate hyperpigmentation like dyskeratosis congenita, dyschromatosis ...
• [7] Important clinical differential diagnoses include dyskeratosis congenita (poikiloderma, leukoplakia and nail dystrophy), Dowling Degos (reticulated ...