True about lung carcinoma -

Ref:Textbook of pathology (Harsh mohan) 6th edition,page no.500 Oat cell carcinoma is composed of uniform, small cells, larger than lymphocytes with dense, round or oval nuclei having diffuse chromatin, inconspicuous nucleoli and very sparse cytoplasm (oat = a form of grain). These cells are organised into cords, aggregates and ribbons or around small blood vessels forming pseudorosettes.Theyare commonly associated with bilateral hilar lymphadenopathy.