PMEL and carcinoma: Any lesion consisting of edema, an extracellular matrix with a high level of mucopolysaccharide, hyaline cartilage content, and necrosis may appear as a cystic mass.[4,6] For differentiating between carcinoma and sarcoma, special immunohistochemical stains using Vimentin, S-100, CK, CK7, EMA, and HMB45 are needed.