A 51-year-old woman presented with two rounded right upper-lobe lung nodules, measuring 3.0 cm and 0.2 cm in greatest dimension. She underwent wedge resection of the masses. Histologic sections revealed the tumor was composed of two cell populations. All neoplastic cells stained positively with TTF-1 and epithelial membrane antigen (EMA) immunohistochemistry, while the lining cells also stained positively with pan-cytokeratin.
Melanie Bois, M.D.
Resident, Division of Anatomic & Clinical Pathology