Skin biopsy of a patient shows evidence of malignant melanoma. Which is the common type of malignant melanoma?

Superficial spreading melanoma comprises approximately 60% to 70% of melanomas and represents the most common melanoma subtype. They often arise in a preexisting nevus and typically develop as a spreading pigmented plaque with irregular borders and variation in color and surface contour. They often exhibit the classic clinical features of melanoma. Areas of regression may result in pink to white areas within the black or brown tumor. They may progress to a veical growth phase faster than lentigo maligna. Ref: Ludgate M.W., Wang T.S. (2009). Chapter 100. Skin Cancer. In J.B. Halter, J.G. Ouslander, M.E. Tinetti, S. Studenski, K.P. High, S. Asthana (Eds), Hazzard's Geriatric Medicine and Gerontology, 6e.