A case of dermatomyositis associated with pseudomyxoma peritonei originating from mucinous adenocarcinoma of the appendix.

A 69-year-old Japanese woman with erythema, severe edema on the face, Gottron's papules and poikiloderma was diagnosed as having dermatomyositis. She also noticed muscle weakness in her extremities, although her electromyogram showed neurogenic patterns. Her levels of CA19-9 and CEA were elevated and a CT of her abdomen revealed a giant, multilobular, cystic lesion in the pelvis. This tumor was diagnosed as pseudomyxoma peritonei originating from a mucinous adenocarcinoma of the appendix.