This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrine, Subject name: Pathology
A 40-year-old male presented with a thyroid swelling and dysphagia. He gave history of on and off watery diarrhea. Biopsy of the lesion is shown. What is your diagnosis? 
Select and explain. 
A. Follicular Ca thyroid, B. Papilllary Ca thyroid, C. Medullary Ca thyroid, D. Anaplastic cell Ca Thyroid
C: Medullary Ca thyroid
Answer: C: Medullary Ca thyroid 
Explanation: Ans. (c) Medullary Ca thyroid*Diarrhea in thyroid tumor can be a paraneoplastic syndromes due to VIP in a case of medullary Ca thyroid. Histology demonstrates abundant deposition of amyloid, visible here as homogeneous extracellular material, derived from calcitonin molecules secreted by the neoplastic cells.