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Current Issue

Summer 2021, Vol. 29 No. 2

Hong Kong J. Dermatol. Venereol. (2021) 29, 94-95

Answers to Dermato-venereological Quiz

Answers to Dermato-venereological Quiz

THB Chan 陳子浩 and MTM Ng 吳孟婷

  1. The clinical differential diagnoses included benign conditions, such as melanocytic nevus and seborrheic keratosis; malignant conditions, such as melanoma and pigmented basal cell carcinoma.
  2. Histopathological section shows large, irregular junctional nests of atypical melanocytes at the rete ridges and focally extending down to the follicular epithelium. These nests are of different sizes and show focal confluence at the dermal-epidermal junction. The atypical melanocytes have large, hyperchromatic nuclei and prominent nucleoli. Mitotic figures are occasionally seen. Upward melanin pigment incontinence into the keratin layer is noted. On immunohistochemical staining, the atypical melanocytes show homogeneous positivity for Melan-A, Ki-67 and HMB-45. The findings are in keeping with a superficial spreading melanoma.
  3. The diagnosis is acralentiginous melanoma.
  4. The initial treatment of primary melanoma is complete excision with a 2-3 mm margin of healthy tissue. It is followed by a radial excision with margins depending on the Breslow thickness of the melanomas which is measured vertically in millimetres from the top of the granular layer to the deepest point of tumour involvement. It is a strong predictor of outcome; the thicker the melanoma, the more likely it is to metastasize. The excision margins is measured from the edge of the melanoma according to the Breslow thickness as follows:
    Melanoma in situ – excision margin 5 mm
    Melanoma <1.0 mm – excision margin 1 cm
    Melanoma 1.0-2.0 mm – excision margin 1-2 cm
    Melanoma 2.0-4.0 mm – excision margin 1-2 cm
    Melanoma >4.0 mm – excision margin 2 cm
    A flap or graft may be required to close the wound. Further surgery or radiotherapy may be considered to ensure complete removal of melanoma

Staging of cutaneous melanoma