PMEL and tuberous sclerosis: According to previous studies, HMB-45 is almost always diffusely expressed in these tumors, and Melan A is also expressed in most cases.1 On ultrastructural examination, the tumor cells show abundant cytoplasmic glycogen premelanosomes, hemidesmosomes, and poor intracellular junctions.8,9 Some tumors of the PEComa group (like angiomyolipoma and lymphangioleiomyomatosis) occur in the background of tuberous sclerosis complex (TSC) syndrome.