Poroma with sebaceous differentiation: dermoscopy for the diagnosis of skin tumor with sebaceous differentiation.

Although divergent adnexal differentiations are occasionally seen in poroma, poroma with sebaceous differentiation is extremely rare. We present here the second case of dermoscopy on poroma with sebaceous differentiation. A 38-year-old Japanese female presented with a 2-year history of a slow-growing nodule on her left forearm. Dermoscopically, fine hairpin-like vessels, beige lobular structures were seen in the nodule. Many small yellow dots were scattered between beige lobular structures, giving orange-beige in color as a whole. On the basis of histopathologic findings, a diagnosis of poroma with sebaceous differentiation was made. Some sebaceous tumors are known to exhibit yellowish structures on dermoscopy. Tumors with sebaceous differentiation, as well as conventional sebaceous tumors, can show yellow structures on dermoscopy.