IM Quiz: Paraneoplastic Syndromes

Small cell neoplasms of the lung are associated with a wide variety of paraneoplastic syndromes, some of which are humorally mediated, while others are of unknown pathophysiology. The Lambert-Eaton myasthenic syndrome, which is associated with proximal muscle weakness and characteristic electromyographic findings, is linked almost exclusively with small cell tumors. Subacute cortical cerebellar degeneration, as exemplified by the findings outlined in scenario B, is associated with small cell tumors and some cases of ovarian cancer, breast cancer and Hodgkin's disease. Cushing's syndrome due to hypersecretion of glucocorticoids and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are also associated with small cell lung tumors, in addition to other cancers. Hypercalcemia is infrequently associated with small cell neoplasms, but it is not an infrequent manifestation of squamous and large cell lung tumors, in which cases it may be a result of secretion of substances with parathyroid hormone-like activity or of another factor associated with the humoral hypercalcemia of malignancy.