Sebaceous-like clear cell changes in primary lung cancer

We examined two cases of primary lung cancer with sebaceous-like clear cells (SLCCs), defined as clear carcinoma cells with microvacuolated cytoplasm and centrally located nuclei, which were selected from among 281 surgical/autopsy cases of lung cancer (2/281, 0.7%). Both cases were higher stage (stage IIA and IIIA), and SLCCs were intermingled with adenocarcinoma cells of usual type. They showed minute mucin staining, no evidence of glycogen, diffuse positivity for epithelial membrane antigen and carcinoembryonic antigen, focal positivity for thyroid transcription factor-1, and negativity for Napsin A and gross cystic disease fluid protein-15. Oil red O stain and ultrastructural examination in both cases failed to reveal lipid in SLCCs. SLCCs could represent non-specific changes of lung adenocarcinoma with a relatively advanced stage, and should be discriminated from true sebaceous differentiation.