dont need spikes on bx, subepithelial deposits on the EM will do

Membranous like glomerulopathy with masked IgG Kappa deposits

• Light microscopy = classic MN, 25% proliferative changes. Routine Negative IF. But on EM you can see the sub epithelial, and mesangial changes.

• Paraffin IF – opens up epitopes for ab to bind. Lights up the masked IgGk deposits.

• Laser capture microdissection suggests serum amyloid P might be an antigenic target

• Young females, preserved renal function, nephrotic range proteinuria, 55% positive ANA, 2% met SLE criteria

• Orphan disease - treatment unclear, 44% CKD/ESKD.

• Can recur in transplant.

• Probably an autoimmune disease rather than paraprotein disease.

MISC

Idiopathic membranous can antigen switch (e.g. IgG1 early and IgG4 later in disease)

NELL 1

• NELL 1 in primary membranous

• ~ 5% +

• 10 years older than primary membranous

• 33% had a history of malignancy

• Folic acid association?

• Mercury containing compounds association?! (e.g. whitening cream)

PLA2r

Beck & Salant KI 2010

Membranous like glomerulopathy with masked IGG kappa despots (MGMID) AKA serum amyloid P associated glomerulopathy

• Requires Paraffin IF to make diagnosis
• Rare, 41 cases, IF neg, paraffin IF – Strong IgG -Kappa staining
• Young (mean age 26), white, vague autoimmune. Tends not have NS. no underlying neoplasia. 25/26 neg electrophoresis. (Larsen, KI reports 2016)
• Laser captures microdissection identified serum amyloid P (using mass spec). Can confirm diagnosis by staining with serum amyloid P.