PTGER4 and skin basal cell carcinoma: -A small, conventional nodular BCC component that transitioned into a predominantly spindle cell-containing, epithelial-like growth.-The BCC was BER-EP4-positive.-The sarcomatoid component was positive for α-SMA, MSA, calponin and p63-Partial positive for S100 and GFAP in epithelial-like cells.