ONCOLOGY

A 54-year-old male comes to the ER with complaints of cough and bloody sputum. He used to smoke 2packs/day for 22 years, but quit last month. He is having weight loss, anorexia, constipation, increased thirst, and easy fatigability, which he thinks is due to his depression. His wife died 4 months ago and “life never felt same after that”. On examination, he is a slim man who appears pale. The vitals are stable though he appears a little irritable and short of breath. You order a complete blood work and chest x-ray and the results are:
Sodium 144 mEq/dL
Potassium 4.3 mEq/dL
Chloride 98 mEq/dL
Bicarbonate 21 mEq/dL
Calcium 11.5 mg/dL
BUN 28 mg/dL
Creatinine 0.8 mg/dL
Chest X Ray Hilar mass in the left lung
What is the most probable diagnosis?

A. Tuberculosis
B. Squamous cell carcinoma of lung
C. Oat cell carcinoma of lung
D. Sarcoidosis
E. Adenocarcinoma of the lung

Explanation:
This patient’s symptoms are suggestive of hypercalcemia, which is confirmed by the laboratory results. Hypercalcemia is usually associated with Squamous Cell Carcinoma of Lungs (Remember sCa++mous) (Choice B) not Oat Cell Carcinoma (Choice C). Hypercalcemia usually develops as a late complication of cancer, and its appearance is very serious. Even though hypercalcemia is frequently due to metastatic involvement of the bone, it is also because of parathormone-related protein (PTHrP). PTHrP is similar to PTH in the receptor binding area. Binding to PTH results in increased calcium resorption from the bones and increased renal calcium resorption in the distal tubule.

The most common symptoms of hypercalcemia are feeling tired, difficulty thinking clearly, lack of appetite, pain, frequent urination, increased thirst, constipation, nausea, and vomiting. Most patients do not experience all of the symptoms of hypercalcemia, and some patients may not have any symptoms at all.

Sarcoidosis (Choice D) does cause hypercalcemia but usually patients have bilateral hilar adenopathy, evidence of erythema nodosum. However, hilar mass in a smoker is most likely a cancer, than anything else.

Hypercalcemia is not normally associated with Tuberculosis (Choice A). TB is very unlikely in USA unless patient has some kind of immunosuppression.

Adenocarcinoma is usually a peripheral lesion and usually not associated with hypercalcemia.