Dermoscopy of reticulate acropigmentation of Kitamura

Reticulate acropigmentation of Kitamura (RAPK) is an uncommon autosomal dominant reticulate pigmentary disorder. RAPK was first observed by Kitamura and Akamatsu in Japan in the year 1943 and reported later by Kitamura in the year 1953.^[1] It is clinically characterized by hyperpigmented and atrophic macules, which are reticulate in configuration. The site of involvement includes the dorsal surface of hands and distal aspect of forearms. There is also the involvement of palms and soles in the form of irregular interruptions of the dermatoglyphics and fine pits.^[1] We, herein, describe a case of reticulate acropigmentation of Kitamura involving the face, bilateral distal forearms, and dorsa of hands, along with its unique dermoscopic features.

A 26-year-old male presented with asymptomatic and slowly progressive dark-colored lesions on his hands and temple area for 5 years. The patient complained of multiple punctate depressed hyperpigmented lesions over the bilateral palms. There was a history of similar complaints in the father, and he was not born of consanguinity. Dermatological examination revealed mildly atrophic, polygonal, and hyperpigmented macules of 0.5–1 mm size in a reticulate pattern involving the face [Figure 1a], dorsal surface of the hands, medial aspect of the both wrists, and lower medial aspect of both forearms [Figure 1b]. No hypopigmented lesions were observed. Multiple pits were present over both palms, with breaks in dermatoglyphics [Figure 1c]. He also had multiple non-acne facial scars, predominantly on the malar areas. Nails and oral cavity were not involved. Based on the history and clinical findings, a diagnosis of RAPK was considered.

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Figure 1:

(a) Multiple hyperpigmented macules distributed (red circle) over the face predominantly on the temple area, along with non-acne facial scars, (b) Multiple hyperpigmented macules distributed over the wrist and forearm (blue circle), (c) Multiple pits (black circle) present over the palm, with breaks in dermatoglyphics.

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Dermoscopic examination was performed at three sites [Figures 2a-c] using a non-polarized contact hand-held Delta 20 dermatoscope (×10 magnification; Heine, Herrsching, Germany) attached to a Nikon SLR camera, with mineral oil as interface media.

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Figure 2:

(a) Dermoscopy from forehead macule shows multiple discrete grey-brown colored irregular dots and globules (blue circle) in an irregular branching pattern (red circle) exhibiting a dark brown background. (b) Dermoscopy from wrist shows light brown irregular pigmentary globule with fine brown dots (black circle). (c) Dermoscopy from palm shows multiple irregular interruptions in the dermatoglyphics with branching brown pigmentary macule with pits (green circle) (Images taken with non-polarized contact hand-held Delta 20 dermatoscope and ×10 magnification).

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RAPK is a pigmentary disorder characterized by predominantly acral reticulate pigmentary lesions and fine reticulate brown pigmentation on dermoscopy.^[2] Facial involvement, as seen in our case, is unusual in RAPK, as are the dermoscopic observations. We also observed that the depressions on the palms and soles coincide with the patchy pigmented spots, a finding not previously reported. Adya et al. reported that the interruptions in the dermatoglyphics on the palm coincide with the fine superficial discrete pits.^[3] The predominant dermoscopic pattern observed was multiple discrete grey-brown irregular dots and globules in an irregular branching pattern against a dark brown background.

Thus, dermoscopy can be a useful imaging modality to diagnose RAPK, in addition to clinical and histological features.