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Keywords:

  • dermoscopy;
  • melanoma;
  • parallel ridge pattern;
  • Peutz–Jeghers syndrome;
  • pigmentation

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Pigmentation due to a dye such as para-phenylenediamine
  5. Acral pigmented macules associated with peutz–jeghers syndrome
  6. Anti-cancer drug-induced hyperpigmentation on the volar skin
  7. Acral subcorneal hemorrhage
  8. Pigmented warts
  9. References

One of the recent advances in dermoscopy is the significance of parallel ridge pattern (PRP), which has 99% specificity in detecting both melanoma in situ and advanced melanoma on the acral volar skin. This review features exceptionally benign acral lesions showing PRP on dermoscopy. These benign lesions can be distinguished from malignant melanoma, because of the typical clinical history and associated symptoms. However, it is sometimes difficult for dermatologists to exclude malignant melanoma and a subsequent skin biopsy should be strongly recommended. These benign lesions include pigmentation due to a dye such as para-phenylenediamine, acral pigmented macules associated with Peutz–Jeghers syndrome, anti-cancer drug-induced hyperpigmentation on the volar skin, acral subcorneal hemorrhage and pigmented warts.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Pigmentation due to a dye such as para-phenylenediamine
  5. Acral pigmented macules associated with peutz–jeghers syndrome
  6. Anti-cancer drug-induced hyperpigmentation on the volar skin
  7. Acral subcorneal hemorrhage
  8. Pigmented warts
  9. References

In Japan, the incidence of malignant melanoma has increased strikingly. Compared with Caucasian patients with malignant melanoma in Western countries where superficial spreading melanoma is the most frequent subtype with a ratio of 70%, acral lentiginous melanoma is the most prevalent clinical phenotype in non-white populations and accounts for approximately half of malignant melanoma in Japan.1–3 In addition, approximately half of Japanese acral lentiginous melanoma cases occur on the sole of the foot.1–3 Therefore, it is important to distinguish malignant melanoma from benign skin lesions when we examine a pigmented macule on the sole. One of the recent advances in dermoscopy is the significance of parallel ridge pattern (PRP), which has 99% specificity in detecting both melanoma in situ and advanced melanoma on the acral volar skin.4–6 This review features exceptionally benign acral lesions showing PRP on dermoscopy. These benign lesions can be distinguished from malignant melanoma, because of the typical clinical history and associated symptoms. However, it is sometimes difficult for dermatologists to exclude malignant melanoma and a subsequent skin biopsy should be strongly recommended.

Pigmentation due to a dye such as para-phenylenediamine

  1. Top of page
  2. Abstract
  3. Introduction
  4. Pigmentation due to a dye such as para-phenylenediamine
  5. Acral pigmented macules associated with peutz–jeghers syndrome
  6. Anti-cancer drug-induced hyperpigmentation on the volar skin
  7. Acral subcorneal hemorrhage
  8. Pigmented warts
  9. References

An occupation-related pigmentation due to para-phenylenediamine was reported to show PRP (Fig. 1).7 It is speculated that para-phenylenediamine on the sole of the patient’s work boot may have been blotted to the cornified layer of the crista cutis. Additionally, two cases of pigmentation and pseudochromhidrosis of the palms due to a self-tanning product were reported.8 Shaving of the cornified layer causes the macules because of a faint dye, and because the pigmentation is limited in the cornified layer. Having an occupation or hobby that involves manipulating dyes is one of the key questions to exclude malignant melanoma.

image

Figure 1.  (a) Pigmented macules on the sole due to para-phenylenediamine. The patient was referred for therapy because of clinically suspected malignant melanoma. (b) The macules showed a parallel ridge pattern on dermoscopy.

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Acral pigmented macules associated with peutz–jeghers syndrome

  1. Top of page
  2. Abstract
  3. Introduction
  4. Pigmentation due to a dye such as para-phenylenediamine
  5. Acral pigmented macules associated with peutz–jeghers syndrome
  6. Anti-cancer drug-induced hyperpigmentation on the volar skin
  7. Acral subcorneal hemorrhage
  8. Pigmented warts
  9. References

The autosomal dominant genetic disease is characterized by small pigmented macules in the lips and acral regions, showing PRP (Fig. 2). Association with benign hamartomatous polyps in the gastrointestinal tract leads to the diagnosis of Peutz–Jeghers syndrome.

image

Figure 2.  (a) Small pigmented macules on the fingers associated with Peutz–Jeghers syndrome. (b) The macules showed a parallel ridge pattern on dermoscopy.

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Anti-cancer drug-induced hyperpigmentation on the volar skin

  1. Top of page
  2. Abstract
  3. Introduction
  4. Pigmentation due to a dye such as para-phenylenediamine
  5. Acral pigmented macules associated with peutz–jeghers syndrome
  6. Anti-cancer drug-induced hyperpigmentation on the volar skin
  7. Acral subcorneal hemorrhage
  8. Pigmented warts
  9. References

Acral pigmented lesions showing PRP sometimes develop after administration of anti-cancer drugs such as 5-fluorouracil (Fig. 3).9

image

Figure 3.  (a) A single pigmented macule on the sole developed after administration of 5-fluorouracil. (b) The macule showed a parallel ridge pattern on dermoscopy.

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Usually, a few pigmented lesions develop simultaneously; however, in some cases, it has occurred as a single macule on the volar skin showing PRP. The medical history is the most useful information to exclude malignant melanoma.

Acral subcorneal hemorrhage

  1. Top of page
  2. Abstract
  3. Introduction
  4. Pigmentation due to a dye such as para-phenylenediamine
  5. Acral pigmented macules associated with peutz–jeghers syndrome
  6. Anti-cancer drug-induced hyperpigmentation on the volar skin
  7. Acral subcorneal hemorrhage
  8. Pigmented warts
  9. References

This appears suddenly on the soles, especially on the heal subjected to body loading after hard work or sports. The lesion shows typical dermoscopic finding called “pebbles” on the ridges (Fig. 4). In patients with sensory loss, such as distal symmetric neuropathy with diabetes mellitus, it can be developed in a daily life.

image

Figure 4.  Acral subcorneal hemorrhage shows typical dermo-scopic finding called “pebbles” on the ridges.

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Pigmented warts5

  1. Top of page
  2. Abstract
  3. Introduction
  4. Pigmentation due to a dye such as para-phenylenediamine
  5. Acral pigmented macules associated with peutz–jeghers syndrome
  6. Anti-cancer drug-induced hyperpigmentation on the volar skin
  7. Acral subcorneal hemorrhage
  8. Pigmented warts
  9. References

The most important differential diagnosis is verrucous malignant melanoma. A report of 20 cases of verrucous malignant melanoma showed that, in over 50% of the cases, benign lesions such as warty nevi, papillomas, seborrheic keratosis or cysts were clinically made.10 Also, in the reported cases of pigmented warts, verrucous malignant melanoma was clinically suspected.11

Plantar warts due to human papillomavirus type 60 are predominantly pigmented when discovered after early adulthood.12 Pathological confirmation and human papillomavirus typing are needed to distinguish pigmented warts from verrucous malignant melanoma.

In this paper, benign acral lesions showing PRP are reviewed. When we see a pigmented lesion on the volar skin, malignant melanoma should be considered and subsequent skin biopsy is strongly recommended. However, a few exceptional cases may also develop PRP on dermoscopy. Dermatologists should know the differential diagnosis of pigmented lesions showing PRP.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Pigmentation due to a dye such as para-phenylenediamine
  5. Acral pigmented macules associated with peutz–jeghers syndrome
  6. Anti-cancer drug-induced hyperpigmentation on the volar skin
  7. Acral subcorneal hemorrhage
  8. Pigmented warts
  9. References