ABSTRACT
Knowledge of the histologic features of pigmented BCCs assists in correlating the dermoscopic structures to the histopathology structures. Under routine microscopic examination, BCC tumors are seen as clusters or islands of basaloid cells found in the dermis or the dermoepidermal junction. Free melanin, melanin in basal cells and in melanocytes or melanophages can be found within basaloid tumor islands, which in turn is responsible for yielding the pigmentations seen under dermoscopy. The different dermoscopic structures correlate to (i) the shape and size of the tumor islands and (ii) to the variation in the amount and distribution of the melanin pigment. Pigmentation found in small islands of tumors may be seen as multiple bluegray globules under dermoscopy. The presence of large amount of pigmentation seen in a large cluster of tumors may correspond to large bluegray ovoid nests. Although classically the basaloid tumor islands appear with a blue-gray color, depending on their depth, they can also appear with brown colors (Tyndall effect). Depending on the shape and confi guration of the pigmented basaloid tumor islands, their appearance can overlap between oval structures, leaf-like, and spoke-wheel-like structures.
