This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Pathology
Which of the following is not true about IgA nephropathy 
Select and explain. 
A. The pathological changes are proliferative and usually confined to mesangial cells; usually focal and segmental, B. Hematuria may be gross or microscopic, C. On immunofluorescence depodits contain IgA and IgG, D. Absence of associated proteinuria is pathognomic
D: Absence of associated proteinuria is pathognomic
Answer: D: Absence of associated proteinuria is pathognomic 
Explanation: IgA nephropathy, characterized by mesangial deposits of IgA-containing immune complexes, is the most common cause of nephritic syndrome worldwide; it is also a common cause of recurrent hematuria; it commonly affects children and young adults and has a variable course. Histologically, the lesions in IgA nephropathy vary considerably.The glomeruli may be normal or may show mesangial widening and segmental inflammation confined to some glomeruli (focal proliferative GN); diffuse mesangial proliferation (mesangioproliferative GN); or (rarely) ove crescentic GN. The characteristic immunofluorescence picture is of mesangial deposition of IgA, often with C3 and properdin and smaller amounts of IgG or IgM. Ref: Robbins basic book of pathology 10th edition page 530