A 60 years old male with history of 60-pack years of smoking is now diagnosed to be suffering from carcinoma lung. Histologic evaluation of the tumor revealed small, highly mitotic cells with hyperchromatic nuclei. Which of the following clinical presentation might occur in the patient during the course of illness?
Correct Answer: Thin limbs and obese trunks
Description: Ans. c. Thin limbs and obese trunks (Ref: Harrison 19/e p610, 2271, 2314, 18/e p745, 829, 2945, 3061-3062; Robbins 9/e p717, 8/e p729, 730)In a 60 years old male with history of 55 pack years, who presented with chronic cough. Biopsy of lung showed small hyperchromatic nuclei and highly mitotic cells, which is suggestive of small cell lung cancer.'Vast majority of lung cancer patients in whom the syndrome of inappropriate antidiuretic hormone (SIADH), Cushing's syndrome, or neurologic paraneoplastic syndrome develop have SCLC'.In patients of Cushing syndrome, there is marked weight gain and centripetal fat redistribution, so this patient most likely will have thin limbs and obese trunks.Histopathology of Small cell carcinoma:Dense sheets of small cells with scant cytoplasmFinely granular nuclear chromatinFrequent mitoses, and inconspicuous or absent nucleoliMitotic rate is characteristically high'Ectopic ACTH production is predominantly caused by occult carcinoid tumors, most frequently in the lungs, but also in thymus or pancreas. Because of their small size, these tumors are often difficult to locate. Advanced small cell lung cancer can cause ectopic ACTH production.'- Harrison 18/e p2945Causes of Cushing's SyndromeFemale; Male Ratio%ACTH-Dependent Cushing's 90Cushing's disease (= ACTH-producing pituitary adenoma)4:175Ectopic ACTH syndrome (due to ACTH secretion by bronchial or pancreatic carcinoid tumors, small cell lung cancer, medullary thyroid carcinoma, pheochromocytoma and others)1:115ACTH-independent Cushing's4:110Adrenocortical adenoma 5-10Adrenocortical carcinoma 1%Rare causes: PPNAD, primary pigmented nodular adrenal disease: AIMAH, ACTH-independent massive adrenal hyperplasia; McCune-Albright syndrome <1%Abbreviations: Acth, adrenocorticotropic hormone; AIMAH, ACTH-independent macronodular hyperplasia; PPNAD, primary pigmented nodular adrenal disease.Small Cell CarcinomaMost malignant, centralQ in distribution, strongly related to smokingQCells are small with little cytoplasm called 'oat cell'QAssociated with massive hilar or mediastinal lymphadenopathy, mediastinal invasion and perihilar massQMC variety associated with paraneoplastic syndrome, Cushing syndrome, hypokalemia and SVC syndromeQMost responsive to chemotherapy (cisplatin + etoposide)Shows response to radiotherapyQHormones produced by small cell carcinoma: ACTH, AVP(vasopressin), calcitonin. ANF, gastrin releasing peptideQBronchial CarcinoidBronchial carcinoids (least malignant) are the most indolent of the spectrum of pulmonary neuroendocrine tumorsMost patients are <40 years; Not related to smokingQLower respiratory tract (Bronchus, lung, trachea) is the MC site of carcinoid tumorQCarcinoid syndrome is uncommonQPathology:Most tumors are confined to main stem bronchus, commonly projects into the lumenQSome tumors penetrate the bronchial wall to fan out in the peri-bronchial tissue producing the collar-button lesionQMost bronchial carcinoidsDo not have secretary activityQDo not metastasize to distant sitesQAre amenable to resectionQ
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