Abstract
An 88-year-old woman presented with a 40×40 mm-sized, light brown nodule with a central ulcer on her lower abdomen. She had noticed the nodule two weeks before the first visit. Dermoscopic examination showed fissures and ridges with many comedo-like openings on the periphery of the nodule. Histopathology demonstrated reticulated seborrheic keratosis (SK), accompanied by solid basal cell carcinoma (BCC) in the center. BCC cells invaded reticulated epithelial strands of SK between them. Immunohistochemistry revealed positive reactivity of only BCC cells for Ber-EP4. Although the pathogenesis of malignant transformation is controversial, solid BCC was supposed to arise from reticulated SK in the present case.[Skin Cancer (Japan) 2013 ; 28 : 310-314]
