[khanar]

A 60 year old woman who has squamous cell carcinoma of the lung came complaigining of right flank pain, fatigue, weakness, anorexia, constipation, and muscle aches. Urine exam showed hematuria. The most likely cause of these symptoms is secretion of which of the following substances by her cancer?

A- Bombesin
B- Calcitonin
C- ACTH
D- Erythropoietin
E- Human chorionic gonadotropin
F- Parathormine related protein

 

[ath.pantelis]

Lung cancers (both small & non-small cell LCA) are notorious for producing a large variety of molecules, which are responsible for manifesting as a constellation of paraneoplastic syndromes. These paraneoplastic syndromes are, by definition, unrelated to the primary focus & frequently make up a confusing setting in clinical practice.

In this very case, however, things are rather clear -- stones, bones, moans, groans push us to suspect hyperparathyroidism (in this case it is secondary) and, this in turn, would safely make us choose F as the correct answer. Paraneoplastic syndrome due to PTH-rp in the setting of NSCC is a very popular & high-yield topic for USMLE.

 

[aungawa]

F- Parathormine related protein

F- Parathormine related protein