A 61-year-old Caucasian female presents to her primary care physician complaining, "I feel terrible lately, coughing much worse than normal. Just very nauseated and tired. My head is pounding and my husband says I'm especially irritable." She also attests to a gradual increase in thirst and a generalized weakness. She has a history of mitral valve prolapse and well-controlled hypertension. Her only medications at this time are atenolol and a multivitamin. From the age of 19, she has smoked one pack of cigarettes per day. She drinks socially on the weekends. Physical examination reveals a thin, pale woman who is mildly wheezing but otherwise appears normal. Chest x-ray shows a four centimeter perihilar mass and increased hilar opacity. What is the most likely diagnosis?

Question

A 61-year-old Caucasian female presents to her primary care physician complaining, "I feel terrible lately, coughing much worse than normal.  Just very nauseated and tired.  My head is pounding and my husband says I'm especially irritable."  She also attests to a gradual increase in thirst and a generalized weakness.  She has a history of mitral valve prolapse and well-controlled hypertension.  Her only medications at this time are atenolol and a multivitamin.  From the age of 19, she has smoked one pack of cigarettes per day.  She drinks socially on the weekends.  Physical examination reveals a thin, pale woman who is mildly wheezing but otherwise appears normal.  Chest x-ray shows a four centimeter perihilar mass and increased hilar opacity.  What is the most likely diagnosis?

Quizplus · Accepted Answer

Explanation: Syndrome of inappropriate antidiuretic hormone (SIADH) can be caused by a multitude of conditions, including tumors, drugs, and disorders of the chest and central nervous system. SIADH is associated with normovolemic hyponatremia and, in this case, is caused by small cell carcinoma (Choice D). In SIADH, the urine is concentrated but the patient is not volume depleted. Initially, the symptoms are mild and nonspecific, but as the serum sodium declines (especially <120 mEq/L), neurologic symptoms, seizures, and coma may ensue. Asbestosis (Choice A) occurs more often in construction and shipyard workers and generally occurs approximately 20 years after the initial exposure to asbestos. The condition is characterized by dyspnea on exertion, cough, chest tightness, and wheezing. Pulmonary fibrosis is evident on CXR or chest CT. Mesothelioma (Choice B) is linked to asbestos exposure. Mesothelioma is often characterized by dyspnea and chest pain, and CXR shows nodular thickening of the pleura and/or obscuring of the diaphragm. Large cell carcinoma (Choice C) accounts for 10-15% of all lung cancers and typically manifests on CXR as a large peripheral mass. Symptoms may include cough and dyspnea. Severe pain may be reported if the parietal pleura or chest wall are infiltrated. Squamous cell carcinoma (Choice E) accounts for 25-30% of all lung cancers and typically manifests on CXR as a cavitary lesion in a bronchus. Symptoms may include cough, dyspnea, wheezing, and hemoptysis. This type of lung cancer is sometimes associated with hypercalcemia due to parathyroid like hormone production. Educational Objective: Syndrome of inappropriate antidiuretic hormone (SIADH) is associated with normovolemic hyponatremia and can be caused by small cell carcinoma of the lung.

A 61-Year-Old Caucasian Female Presents to Her Primary Care Physician