Fig. 3

Immunohistochemistry of the acantholytic squamous cell carcinoma of the lung. a The pleomorphic tumor cells are diffusely positive for cytokeratin 5 (CK5). b–e The monomorphic, acantholytic tumor cells, mainly seen in lymphatic duct of the bronchial wall, are diffusely positive for CK5 (b) and p40 (c) and almost negative for vimentin (d). The acantholytic tumor cells are largely positive for E-cadherin (e), but the low intensity of the cellular membrane is notable (inset, high magnification of (e). The bronchial epithelium (left side of (b–e) is an internal positive control for CK5 (b), p40 (c), and E-cadherin (e) and the bronchial stromal cells are internal positive controls for vimentin. Bars indicate 100 μm