The Endocrine System
A62 year-old woman Omvati with advance4 metastatic lung cancer develops profound fatigue and weakness and alternating diarrhea and constipation. Physicel examination demonstrates hyperpigmentation of skin, even in areas protected from the sun. Tumor involvement of which endocrine organ is most strongly suggested by this patient's presentation? (AIIMS May 2012)
This is Addison disease, in which severe adrenal disease produces adrenocortical insufficiency. Causes include autoimmune destruction, congenital adrenal hyperplasia, hemorrhagi necrosis and replacement of the glands by either tumor (usually metastatic) or granulomatous diseases (usually tuberculosis).The symptoms can be subtle and nonspecific (such as those illustrated, so a high clinical index of suspicion is warranted. Skin hyperpigmentation is a specific clue that may be present on physical examination, suggesting excess pituitary ACTH secretion. (The ACTH precursor has an aminoacid sequence similar to MSH, melanocyte stimulating hormone.) Most patients have symptoms (fatigue, gastrointestinal
distress) related principally to glucocorticoid deficiency. In some cases, however, mineralocorticoid replacement may also be needed for symptoms of salt wasting with lower circulating volume.
• Except in the case of primary pancreatic cancer, complete tumor replacement of the endocrine pancreas (option B) would be uncommon. ln any event, pancreatic involvement would be associated with diabetes mellitus.
• Involvement of the ovaries (option C) by metastatic tumor (classically gastric adenocarcinoma) would produce failure of menstruation.
• lnvolvement of the pituitary gland (option D) could produce Addisonian symptoms, but the pigment skin suggests a primary adrenal problem rather than pituitary involvement.