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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor= {{YD}} (Reviewed by  {{YD}})
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|Prompt=A 45 year old Caucasian male patient is referred by the primary care physician to the nephrologist's office for nephrotic-range proteinuria. Physical examination is remarkable for high blood pressure and lower extremity edema. Following appropriate work-up, the patient is found to have elevated levels of anti-phospholipase A2 receptor (PLA2R) antibodies. The patient undergoes a kidney biopsy that shows subepithelial deposits and capillary wall thickening with normal cellularity. Anti-PLA2R IgG antibodies and C3 deposits are also observed on immunofluorescence. What is the most likely diagnosis of this patient's condition?
|MainCategory=Pathophysiology
|Explanation=Membranous nephropathy (MN) or membranous glomerulonephritis (MGN) is a common glomerulonephritis that usually presents with nephrotic-range proteinuria, edema, and hypertension. MN is generally classified as primary (idiopathic) or secondary to other systemic disease, such as infections, malignancies, vasculitides etc. Primary MN has been recently associated with the presence of a newly discovered phospholipase A2 receptor (PLA2R) nephrotigenic antigen on the membrane surface of glomerular podocytes and anti-PLA2R antibodies. Kidney biopsy remains the gold standard for the diagnosis of MN, showing subepithelial deposits with capillary wall thickening and IgG deposition under immunofluorescence. On electron microscopy, MN shows a "spike and dome" appearance with subepithelial deposits. While MN is widely considered a chronic condition with a waxing and waning course, it is usually self-limited in the majority of the cases. Heavy proteinuria, a significant marker of prognosis, indicates the need for intervention, usually with corticosteroids and immunosuppressive therapy.
|SubCategory=Renal
|MainCategory=Pathophysiology
|SubCategory=Renal
|MainCategory=Pathophysiology
|SubCategory=Renal
|MainCategory=Pathophysiology
|MainCategory=Pathophysiology
|MainCategory=Pathophysiology
|SubCategory=Renal
|MainCategory=Pathophysiology
|SubCategory=Renal
|MainCategory=Pathophysiology
|SubCategory=Renal
|MainCategory=Pathophysiology
|SubCategory=Renal
|MainCategory=Pathophysiology
|MainCategory=Pathophysiology
|SubCategory=Renal
|Prompt=A 45-year-old man is referred by the primary care physician to the nephrologist's office. The patient is found to have elevated levels of anti-phospholipase A2 receptor (PLA2R) antibodies. The patient then undergoes a kidney biopsy that demonstrates subepithelial deposits and capillary wall thickening with normal cellularity. Anti-PLA2R IgG antibodies and C3 deposits are also observed on immunofluorescence. What is the most likely clinical presentation associated with this patient's condition?
|Explanation=Membranous nephropathy (MN) or membranous glomerulonephritis (MGN) is a common glomerulonephritis that usually presents with nephrotic-range proteinuria, edema, and hypertension. MN is generally classified as primary (idiopathic) or secondary to other systemic disease, such as infections, malignancies, or vasculitides. Primary MN has been associated with the presence of a newly discovered phospholipase A2 receptor (PLA2R) nephrotigenic antigen on the membrane surface of glomerular podocytes and anti-PLA2R antibodies. Kidney biopsy remains the gold standard for the diagnosis of MN, which demonstrates subepithelial deposits with capillary wall thickening and IgG deposition under immunofluorescence. On electron microscopy, MN shows a "spike and dome" appearance with subepithelial deposits. While MN is widely considered a chronic condition with a waxing and waning course, it is usually self-limited in the majority of cases. Heavy proteinuria, a significant marker of prognosis, indicates the need for intervention, usually with corticosteroids and immunosuppressive therapy.
|AnswerA=Cola-colored urine and high blood pressure
|AnswerAExp=Hematuria and hypertension are signs of nephritic syndrome, which are common findings among patients with glomerulonephritis such as IgA nephropathy and rapidly progressive glomerulonephritis. In children, post-infectious glomerulonephritis and Alport syndrome are common etiologies of nephritic syndrome.
|AnswerB=Peripheral edema and frothy urine
|AnswerBExp=Membranous nephropathy is characterized by the presence of antibodies against phospholipase A2 receptor (PLA2R). Most commonly, patients present with nephrotic syndrome, which is characterized by hypoalbuminemia, peripheral edema, dyslipidemia, and albuminuria (frothy urine).
|AnswerC=Urination that awakens the patient at night
|AnswerCExp=Patients with membranous nephropathy do not classically have nocturia. Nocturia may be the first sign of renal insufficiency.
|AnswerD=Burning sensation upon urination
|AnswerDExp=Dysuria is a symptom of urinary tract infection.
|AnswerE=Malar rash, pallor, and photosensitivity
|AnswerEExp=These are the classical findings of systemic lupus erythematosus (SLE). Patients with SLE may progress with renal involvement (commonly lupus nephritis). Lupus nephritis has a wide range of presentations and several sub-types.
|EducationalObjectives=Anti-phospholipase A2 receptor antibodies are nephritogenic antibodies associated with membranous nephropathy. They are classically present in sera of patients with membranous nephropathy and as IgG deposits on podocyte surfaces.


Educational Objective:
|References=Beck LH Jr, Bonegio RG, Lambeau G, et al. M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy. N Engl J Med. 2009;361(1):11-21.<br>
Anti-phospholipase A2 receptor antibodies are recently discovered to be the nephritogenic antibodies implicated in membranous nephropathy. They are classically present in sera of patients with membranous nephropathy and as IgG deposits on podocyte surfaces.
Qin W, Laurence H, Beck LH Jr, Zeng C, et al. Anti-phospholipase A2 receptor antibody in membranous nephropathy. J Am Soc Nephrol. 2011;22:1137-1143.<br>
 
First Aid 2014 page
Reference:
Beck LH Jr, Bonegio RG, Lambeau G, et al. M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy. N Engl J Med. 2009;361(1):11-21.
 
Qin W, Laurence H, Beck LH Jr, Zeng C, et al. Anti-phospholipase A2 receptor antibody in membranous nephropathy. J Am Soc Nephrol. 22:1137-1143.
 
|AnswerA=Membranoproliferative glomerulonephritis often shows glomerular basement membrane (GBM) splitting on pathology due to mesangial ingrowth.
|AnswerAExp=These are not the classical findings of membranoproliferative glomerulonephritis.
|AnswerB=Membranous nephropathy
|AnswerBExp=Membranous nephropathy is characterized by the presence of antibodies against phospholipase A2 receptor. (PLA2R)
|AnswerC=IgA nephropathy
|AnswerCExp=In IgA nephropathy, 30-50% of patients have elevated IgA1 levels.
|AnswerD=Rapidly progressive glomerulonephritis
|AnswerDExp=These are not the classical findings of rapidly progressive glomerulonephritis (RPGN). RPGN usually presents with hematuria and rapidly worsening kidney function over only a few weeks. On pathology, RPGN is characterized classically by crescent formation.
|AnswerE=Lupus nephritis
|AnswerEExp=These are not the classical findings of lupus nephritis. Lupus nephritis has a wide range of presentations and several sub-types.
|RightAnswer=B
|RightAnswer=B
|WBRKeyword=membranous, nephropathy, PLA2R, antibodies, antibody, phospholipase, A2, receptor, receptors, subepithelial, deposits, IgG, C3, complement, glomerulonephritis, nephrotic, syndrome, proteinuria, hypertension, edema, spike, dome, immunofluorescence, renal, kidney, biopsy, light, microscopy, electron
|WBRKeyword=Membranous nephropathy, PLA2R, Phospholipase A2 receptor, Kidney biopsy, Renal biopsy
|Approved=No
|Approved=Yes
}}
}}

Latest revision as of 01:47, 28 October 2020
Author [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pathophysiology
Sub Category SubCategory::Renal
Prompt [[Prompt::A 45-year-old man is referred by the primary care physician to the nephrologist's office. The patient is found to have elevated levels of anti-phospholipase A2 receptor (PLA2R) antibodies. The patient then undergoes a kidney biopsy that demonstrates subepithelial deposits and capillary wall thickening with normal cellularity. Anti-PLA2R IgG antibodies and C3 deposits are also observed on immunofluorescence. What is the most likely clinical presentation associated with this patient's condition?]]
Answer A AnswerA::Cola-colored urine and high blood pressure
Answer A Explanation [[AnswerAExp::Hematuria and hypertension are signs of nephritic syndrome, which are common findings among patients with glomerulonephritis such as IgA nephropathy and rapidly progressive glomerulonephritis. In children, post-infectious glomerulonephritis and Alport syndrome are common etiologies of nephritic syndrome.]]
Answer B AnswerB::Peripheral edema and frothy urine
Answer B Explanation [[AnswerBExp::Membranous nephropathy is characterized by the presence of antibodies against phospholipase A2 receptor (PLA2R). Most commonly, patients present with nephrotic syndrome, which is characterized by hypoalbuminemia, peripheral edema, dyslipidemia, and albuminuria (frothy urine).]]
Answer C AnswerC::Urination that awakens the patient at night
Answer C Explanation AnswerCExp::Patients with membranous nephropathy do not classically have nocturia. Nocturia may be the first sign of renal insufficiency.
Answer D AnswerD::Burning sensation upon urination
Answer D Explanation AnswerDExp::Dysuria is a symptom of urinary tract infection.
Answer E AnswerE::Malar rash, pallor, and photosensitivity
Answer E Explanation AnswerEExp::These are the classical findings of systemic lupus erythematosus (SLE). Patients with SLE may progress with renal involvement (commonly lupus nephritis). Lupus nephritis has a wide range of presentations and several sub-types.
Right Answer RightAnswer::B
Explanation [[Explanation::Membranous nephropathy (MN) or membranous glomerulonephritis (MGN) is a common glomerulonephritis that usually presents with nephrotic-range proteinuria, edema, and hypertension. MN is generally classified as primary (idiopathic) or secondary to other systemic disease, such as infections, malignancies, or vasculitides. Primary MN has been associated with the presence of a newly discovered phospholipase A2 receptor (PLA2R) nephrotigenic antigen on the membrane surface of glomerular podocytes and anti-PLA2R antibodies. Kidney biopsy remains the gold standard for the diagnosis of MN, which demonstrates subepithelial deposits with capillary wall thickening and IgG deposition under immunofluorescence. On electron microscopy, MN shows a "spike and dome" appearance with subepithelial deposits. While MN is widely considered a chronic condition with a waxing and waning course, it is usually self-limited in the majority of cases. Heavy proteinuria, a significant marker of prognosis, indicates the need for intervention, usually with corticosteroids and immunosuppressive therapy.

Educational Objective: Anti-phospholipase A2 receptor antibodies are nephritogenic antibodies associated with membranous nephropathy. They are classically present in sera of patients with membranous nephropathy and as IgG deposits on podocyte surfaces.
References: Beck LH Jr, Bonegio RG, Lambeau G, et al. M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy. N Engl J Med. 2009;361(1):11-21.
Qin W, Laurence H, Beck LH Jr, Zeng C, et al. Anti-phospholipase A2 receptor antibody in membranous nephropathy. J Am Soc Nephrol. 2011;22:1137-1143.
First Aid 2014 page]]

Approved Approved::Yes
Keyword WBRKeyword::Membranous nephropathy, WBRKeyword::PLA2R, WBRKeyword::Phospholipase A2 receptor, WBRKeyword::Kidney biopsy, WBRKeyword::Renal biopsy
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