This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pathology
de Quervain's thyroiditis is characterized by- 
Select and explain. 
A. Mononuclear cell infiltration, B. Histiocytic reaction, C. Giant cell infiltration, D. Eosinophilia
C: Giant cell infiltration
Answer: C: Giant cell infiltration 
Explanation: De Quervain thyroiditis or granulomatous thyroiditis is believed to be triggered by viral infection. It is characterised by giant cell infiltration on microscopy. Multinucleate giant cells enclose naked pools or fragments of colloid. Aggregates of lymphocytes ,activated macrophages and plasma cells are also seen associated with collapsed and damaged thyroid follicles. Ref: Robbins and cotrans 9e Pg 1088 Ref img