Basal
cell carcinoma is the most common malignant tumor of the eyelids, usually
involving the lower lid and medial canthal area.Exposure to sunlight is thought to be an important causative
factor.Clinically, several
variants may be seen (#21847) (#21849): nodular or nodular-ulcerative,
cystic, multicentric, and morpheaform.Histologically, the nodular and the nodular-ulcerative types are
composed of anastomosing nests and cords of proliferative epidermal
basilar cells (#21850).The cells have a darkly staining nucleus with minimal
cytoplasm.A palisading of
nuclei at the edge of the invasive tumor nests is distinctive
(#21855)The cystic type of BCC is similar histologically to the nodular
type, with the exception of central necrosis with cystic spaces (#21852)
(#21853).In the morpheaform BCC, the tumor cells tend to penetrate into the
dermis diffusely as branching cords of cells within a dense connective
tissue matrix (#21856).It
may be very difficult to clinically estimate the margins of morpheaform
BCC because of the diffuse infiltration of the skin.
