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Letter

New Dermoscopic Keys for Circumscribed Acral Hypokeratosis: Report of Four Cases

Author Affiliation(s)

Introduction

Descriptions of the dermoscopic features of acral hypokeratosis (AH) are few. Clinically it can resemble other entities, such as Bowen disease or porokeratosis of Mibelli. Although AH is considered a benign pathology, in 2010 a case with actinic keratosis in the hypokeratosic epidermis and underlying elastosis was reported [ 1 ] , hence the importance of knowing the dermoscopic findings for an early diagnosis and to rule out other differential or coexisting diagnoses.

Case Presentation

Our case series was comprised of 4 patients with AH confirmed by biopsy in the hypothenar eminence. Figure 1A shows AH in a 61-year-old and Figure 1B a 78-year-old woman with a 10-year history of AH. Dermoscopy revealed pink areas on a red milky blush with scattered red dots, step-like scales at the periphery, and elongated whitish structures in a fibrillar raindrop pattern ( Figure 1, C and D ).

Figure 1 .

Clinical and dermoscopic features. (A and B) Cases 1 and 2: Atrophic erythematous plaque with an irregular hyperkeratotic border. (C) Dermoscopy shows pink areas on a red milky blush with scattered red dots, step-like scales at the periphery and elongated whitish structures in a raindrop pattern. (D) Dermoscopy shows red milky blush, pink islets with dotted vessels, elongated whitish structures in raindrop pattern and staircase sign. (E) Case 3: Depressed erythematous plaque, surrounded by an hyperkeratotic border. (F) Dermoscopy showed a red dot pattern over a homogeneous red-yellow area.

The third case corresponded to asymptomatic AH ( Figure 1E ) that had developed 2 weeks after a cutting wound in a 30-year-old woman. Dermoscopy showed a red dot pattern over a homogeneous red-yellow area ( Figure 1F ). The fourth case was a 54-year-old woman affected by AH for 8 years ( Figure 1G ). Dermoscopy revealed a fine white pseudonetwork, pink stiff areas on a red milky blush with red dots, step-like scales at the periphery, and elongated whitish structures in a fibrillar raindrop pattern. ( Figure 1H ). Microscopy revealed an area of hypokeratosis demarcated by a sharp and frayed cut-off from uninvolved acral skin with discrete hypogranulosis, dilated blood vessels in the papillary dermis, and slightly thickened collagen fibers in the reticular dermis ( Figure 2 ).

Figure 2 .

Histology displays an area of hypokeratosis demarcated by a sharp and frayed cut-off from uninvolved acral skin with discrete hypogranulosis, dilated blood vessels in the papillary dermis and slightly thickened collagen fibers in the reticular dermis (H&E, ×10).

Conclusions

Previous case series reported star-like desquamation at the periphery, and a well-demarcated erythema with reddish dots. These structures correlate with histopathological studies showing a sharply demarcated area of hypokeratosis, dilated capillaries in the papillary dermis and vessels in the upper reticular dermis [ 2 ] . A recent case report of congenital plantar AH showed a white thin scale and a reticulated surface with no visible acrosyringia opposing the typical dermoscopic acral pattern [ 3 ] .

Our study revealed different dermoscopic findings than previously published: A fine white pseudonetwork and elongated whitish structures in a “raindrop pattern” found in those patients with longstanding AH and could be correlated with the increasing collagen proliferation and thickening. Thus in our case of 2-weeks’ onset AH, only a yellowish-red blush and red dots with peripheral step-like scales were distinguishing.

References

  1. Premalignant circumscribedpalmar hypokeratosis: a new form of circumscribed palmar hypokeratosis? Case report and literature review Kanitakis J, Lora V, Balme B, Roby J. Dermatology.2010;220(2):143-146. CrossRef PubMed
  2. Circumscribed palmar hypokeratosis: correlation between histopathological patterns and dermoscopic findings Nishimura M, Nishie W, Nakazato S, Nemoto-Hasabe I, Fujita Y, Simizu H. Br J Dermatol.2012;167:221-222. CrossRef PubMed
  3. Congenital circumscribed plantar hypokeratosis Bassi A, Oranges T, Massi D, Piccolo V, Mazzatenta C, Neri I. Int J Dermatol.2020;59(10):e367-e369. CrossRef PubMed

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