This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
A 65 years old male diagnosed by biopsy a case of lung carcinoma, with paraneoplastic syndrome and increased PTH. Probable cause is- 
Select and explain. 
A. Parathyroid, B. Parathyroid related peptide, C. Calcitonin, D. Calcitonin related peptide
B: Parathyroid related peptide
Answer: B: Parathyroid related peptide 
Explanation: Hypercalcemia is seen in squamous cell carcinoma of lung. The causal mechanism is the production of calcemic humoral substances, most impoantly parathyroid hormone-related protein ( PTHRP) . It has sone biological action similar to PTH. Several other factors like IL-1, TGF, TNF and dihydroxy vitamin D have also been implicated ( Pathologic basis of Disease, 8 th edition)