This ASN, a paradigm shift of thinking was mentioned.
The thinking now is to think of it more like a pattern of injury and classify based on immunofluorescence (IF) rather than EM.
The four major categories are:
Immune complex : chronic infection related or auto immune
Complement dysregultion : familial and acquired, the c3 glomerulopathies
Chronic tma: atypical hus, other TMAs, APLAS
Paraprotein. Any variant can come here, that is monoclonal
Old classification: Based on extent of deposits on EM and where they are
New classification: Based on pathophysiology and IF findings more
So If you have IgG and C3 on IF:- then think more immune complex based
If you have Ig G monoclonal:- think monoclonal disease
If you have C3 only:- think C3 glomerulopathies or Dense Deposit Disease
If you have No C3 or IgG:- then think TMA
Idiopathic MPGN in an adult is a diagnosis of exclusion, more common in children and its usually polyclonal and C3 positive.
So think differently when thinking about MPGN from now on. Always a tough disease to battle
take a look at a prior concept map on this