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Current Issue

Summer 2021, Vol. 29 No. 2

Hong Kong J. Dermatol. Venereol. (2021) 29, 87-88

Dermato-venereological Quiz

Dermato-venereological Quiz

THB Chan 陳子浩and MTM Ng 吳孟婷

A 63-year-old man presented with pigmented spot on his right sole since childhood. It was noted to increase in size for one year recently. It was asymptomatic all along. There was no systemic symptom. He had a medical history of coronary artery disease and benign prostate hypertrophy. Physical examination revealed a thin dark brownish patch of 1 cm in diameter at the center of the right sole (Figure 1). There was no regional lymph nodes palpable. A skin biopsy was undertaken at the right sole (Figures 2-7).

Figure 1

Figure 2 H&E (10X)

Figure 3 H&E (20X)

Figure 4 H&E (40X)

Figure 5 Melan-A stain

Figure 6 Ki-67 stain

Figure 7 HMB-45 stain


  1. What are the differential diagnoses?
  2. What are the histological findings of the skin biopsy?
  3. What is the diagnosis?
  4. What is the treatment?