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RAK - DDD
Letter to the Editor
Reticulate acropigmentation of Kitamura (RAK)
Kh. Al Aboud and Kh. Al Hawsawi
Reticulate acropigmentation of Kitamura (RAK) and Dowling-Degos Disease (DDD) are characterized by progressive symmetric and asymptomatic reticulated pigmented macules but no hypopigmented macules on the dorsa of hands and feet for the former and flexures for the latter. The histopathology of the hyperpig-mentation in both RAK and DDD are similar and is very characteristic (1). Figure 1.
In DDD there are filiform downgrowths of the epidermis and also variably dilated pilosebacoues follicles. Small horny cysts and comedo-like lesions are also present. Hyperpigmentation is quite pronounced at the tips of the rete ridges. DDD resembles the adenoid form of seborrhoic keratosis. In RAK the appearance resembles those seen in a solar lentigo with club-shaped elongations of the rete ridges but with intervening epidermal atrophy, melanin incontinence and perivascular lymphocytic infiltrate.
Kitamura and Akamatsu first described RAK in Japanese patients in 1943 (2). Dowling in 1938 and Degos in 1954 are the first two authors who described DDD (3, 4). Later in 1978, Wilson Jone and Grice are the first authors who characterized DDD (5).
There have been seven previous reports of RAK-DDD overlap in medical literature. Table 1 shows these reports.
It is clear from these reports that RAK or DDD may not be separate diseases, but different phenotypes of a single disorder.
Figure 1. Skin biopsy from a patient with RAK-DDD, showing filiform elongation of rete ridges with clumps of heavy melanin pigment at their tips.
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RAK - DDD
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Table 1 - The previous reports of RAK - DDD overlap.
Authors	No. of Cases	Mode of Age of onset inheritance (years)		Other family members with one of the following: RAK, RAD*, DDD
Al Hawsawi6 et al	1 female	Sporadic	20	-
Berth-Jones J and Graham Brown RA7	2 females, 1 male	AD	7-14	Absent
Cox NH and Long E8	1 male	Sporadic	36	-
Crovato et al9	1 female	AD	Early thirties	Present (2 cases)
Dhar S et al10	1 male	AD	Not available	Present (2 cases)
Lestringant GG et al11	3 females, 1 male	AD	22-35	Present (The number unknown)
Ostlere L and Holden CA12	2 females, 1 male	AD	*10 (one patient)	Absent
			*not mentioned	
			for others	
Thami GP et al13	1 female	AD	15	Present (12 cases)
* RAD is Reticulate Acropigmentation of Dohi, another dyschromatic disorder.
R E F E R E N C E S -
1.	Spielvogel RL, Kantor GR. Pigmentary disorders of the skin. In: Elder D, Elenitsas R, Jaworsky G, Johnson B, Jr. Histopathology of the skin. 8th Edn. Philadelphia: Raven Publication; 1997: 617.
2.	Kitamura K, Akamatsu S. Rinsho no Hifu Hitsunyo 1943; 8: 201 (Quoted by Griffths, 1976).
3.	Dowling GB, Freudenthal W. Acanthosis nigricans. Br J Dermatol 1938; 50: 467-71.
4.	Degos R, Ossipowski B. Dermatose pigmentaire reticule des pils. Ann Dermatol Syphiligr 1954; 81: 147-51
5.	Wilson-Jones E, Grice K. Reticulate pigmented anomaly of the flexures. Arch Dermatol 1978; 114: 1150-7.
6.	Al Hawsawi K, Al Aboud K, Al Fadley A, Al Aboud D. Reticulate acropigmentation of Kitamura-Dowling Degos disease overlap: a case report. Int J Dermatol 2002; 41(8): 518-20.
7.	Berth-Jones J, Graham-Brown RA. Families with Dowling-Degos disease showing features of Kitamura's reticulate acropigmentation. Br J Dermatol 1989; 120: 463-6.
8.	Cox NH, Long E. Dowling-Degos disease and Kitamura's reticulate acropigmentation: support for the concept of a single disease. Br J Dermatol 1991: 125: 169-71.
9.	Crovato F, Desirello G, Rebora A. Is Dowling-Degos disease the same disease as Kitamura's reticulate acropigmentation? Br J Dermatol 1983; 109(1): 105-10.
10.	Dhar S, Kanwar Aj, Jebraili R, Dawn G, Das A. Spectrum of reticulate flexural and acral pigmentary disorder in northern India. J Dermatol 1994; 21: 598-603.
11.	Lestringant GG, Masouye I, Frossard PM, Adeghate E. Galadari IH. Co-existence of leukoderma with features of Dowling-Degos disease: reticulate acropigmentation of Kitamura spectrum in five unrelated patients. Dermatology 1997; 195: 337-43.
12.	Ostlere L, Holden CA. Dowling-Degos disease associated with Kitamura's reticulate acropigmentation. Clin Exp Dermatol 1994; 19: 492-5.
13.	Thami GP, Jaswal R, Kanwar Aj, Radotra BD, Singh IP. Overlap of Reticulate Acropigmentation of Kitamura, Acropigmentation of Dohi and Dowling-Degos disease in four generations. Dermatology 1998; 196: 350-1.
KhalidAlAboud, MD, dermatologist, Dermatology Unit, Department of Medicine, King Faisal Hospital, Taf, Saudi Arabia. P.O Box. 5440, Makkah, SaudiArabia, e- mail:amoa65@hotmail.com Khalid Al Hawsawi, MD, dermatologist, same address
AUTHORS' ADDRESSES
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• Acta Dermatoven APA Vol 12, 2003, No 4