Small cell carcinoma of lung usually grows in solid diffuse sheets. Other patterns such as ribbons, nesting, anastomosing trabeculae, peripheral palisading, tubules, ductules, and rosettes are less commonly seen. The image shows sheets and clusters of tumor cells separated by delicate vascular septa. There is a hint of peripheral palisading and some clusters have central necrosis. In the current WHO classification of lung cancers (2015), small cell carcinoma is classified as pure or combined (admixed with other cell types). The category mixed small cell/large cell carcinoma has been dropped.