Are You Confident of the Diagnosis?

Characteristic findings on physical examination

Reticulate (or reticular) acropigmentation of Kitamura is characterized by asymptomatic hyperpigmented macules, often with an angular or irregular shape, that first arise on the dorsal hands and feet and later develop in a more reticulate pattern on other parts of body (Figure 1). The macules are noted to have an atrophic quality to them. In addition, pits of epidermal atrophy are found on the palms and soles.

Figure 1.

Reticulate (or reticular) acropigmentation of Kitamura.

Expected results of diagnostic studies

The diagnosis is confirmed by biopsy, which shows:

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  • Epidermal atrophy

  • Elongated rete ridges

  • Hypermelanosis of the basal layer

  • Increased number of melanocytes in basal layer

Diagnosis confirmation

The differential diagnosis of reticular acropigmentation of Kitamura includes:

  • Acropigmentation of Dohi: A more common autosomal dominant disorder caused by mutations in the DSRAD gene and characterized by mottled hyperpigmentation and hypopigmentation largely confined to the dorsal hands and feet.

  • Dowling-Degos disease: Unlike reticular acropigmentation of Kitamura, the reticular pigmentation is centered around the flexural areas and is hyperplastic, not atrophic.

  • Dyschromatosis universalis hereditaria: A type of dyschromia characterized by hyperpigmented and hypopigmented macules in a generalized distribution.

Who is at Risk for Developing this Disease?

Reticular acropigmentation of Kitamura is usually inherited in an autosomal dominant fashion, though not always. The majority of reported cases have occurred in people of Asian descent. It arises in the first and second decades of life.

What is the Cause of the Disease?

The cause of reticular acropigmentation of Kitamura is unknown.

Systemic Implications and Complications

There are no reported systemic implications or complications.

Treatment Options

1. Observation and reassurance

2. Topical options

  • Azelaic acid 15-20% cream or ointment applied twice daily

  • Tretinoin 0.02-0.1% cream apply daily

  • Adapalene 0.1% cream or lotion apply daily

  • Hydroquinone 4% cream apply twice daily

Optimal Therapeutic Approach for this Disease

Observation and reassurance is the best approach to this disease.

If the patient desires treatment, azelaic acid has been shown to be helpful in several limited case reports, so this should be considered the first-line treatment. If this fails, the relative safety of the other topical agents may lead to a therapeutic trial of one or more of the other agents for two-three months to the affected area.

There are no studies regarding the use of lasers to treatment the pigmentation. However, the Erbium:YAG laser has been used with success in the treatment of Dowling-Degos disease so use of this laser may be considered.

Patient Management

Patients with this rare disorder should be reassured and counseled regarding the benign nature of the disorder, the genetic implications, and the paucity of effective treatments. Routine follow-up is not necessary.

Unusual Clinical Scenarios to Consider in Patient Management

There are increasing reports of cases of reticular acropigmentation of Kitamura overlapping with Dowling-Degos disease in the same patient. This implies that the two disorders may lie on a spectrum with one another.

What is the Evidence?

Al Hawsawi, K, Al Aboud , K, Alfadley, A, Al Aboud, D. “Reticulate acropigmentation of Kitamura-Dowling Degos disease overlap: a case report”. Int J Dermatol. vol. 41. 2002. pp. 518-20. (Describes a patient with features of both reticulate acropigmentation of Kitamura and Dowling-Degos disease. Discusses the likelihood that these two disorders lie on a spectrum and have similar expression.)

Gatti, S, Nini, G. “Treatment of reticulate acropigmentation of Kitamura with azelaic acid”. J Am Acad Dermatol. vol. 29. 1993. pp. 666-7. (Discusses a single case of reticulate acropigmentation successfully treated with 20% azelaic acid ointment.)

Kocatürk, E, Kavala, M, Zindanci, I, Zemheri, E, Koç, MK, Sarigül, S. “Reticulate acropigmentation of Kitamura: report of a familial case”. Dermatol Online J. vol. 14. 2008. pp. 7(A single case report of a mother and daughter with familial acropigmentation of Kitamura.)

Sharma, R, Chandra, M. “Pigmentation and pits at uncommon sites in a case with reticulate acropigmentation of Kitamura”. Dermatology. vol. 200. 2000. pp. 57-8. (A report of a case of reticulate acropigmentation with extensive pitting.)

Singal, A, Bhattacharya, SN, Baruah, MC, Indrayan, A, Singh, N. “Is the heredity of reticulate acropigmentation of Kitamura always autosomal dominant”. J Dermatol. vol. 25. 1998 Jan. pp. 57-9. Questions the belief that acropigmentation of Kitamura is inherited in an autosomal dominant fashion. The authors report 3 families with the disorder but the inheritance pattern was clearly not autosomal dominant in all three.