Small cell carcinoma features are

Small cell carcinomas are frequently hilar or central in location,have strong relationship to cigarette smoking and are highly malignant tumours.They are most often associated with ectopic hormone production because of the presence of neurosecretory granules in majority of the tumour cells.Hence they can produce paraneoplastic syndrome.Major hormones produced include ACTH,ADH,Parathormone,Calcitonin,Gonadotropins,Serotonin,etc. Ref Davidson edition23rd pg 614