Pathology and Laboratory Service, Veterans Medical Center and Department of Pathology, LSU Medical Center, New Orleans, Louisiana.

A. Check lists have been introduced in surgical pathology (tumor pathology) to make the study of the biopsies more organized, avoid omissions, make the pathology reports more uniform and complete, and improve communications with the clinicians. In our experience these checklists are also very helpful to gather information from renal biopsies and to grade and stage the lesions in the nephropathies. In the present page we introduce the use of a checklist in Systemic Lupus Erythematosus (SLE) biopsies. This is a complementary paper to the paper on "Una clasificacion facil para LES" published also in cin2000 (http://www.uninet.edu/cin2000)

B. Pathogenically SLE has two basic classes of glomerulonephritis, these may also be mixed. 1. The erroneously called proliferative GN (GN) (WHO classes IB, II-IV) is plainly called glomerulonephritis by WHO. We gave this GN a descriptive name: Pleomorphic (the deposits are of different sizes and shapes) pan glomerular glomerulonephritis (the deposits are lodged in all the components of the glomeruli) (PPGN). 2. Membranous GN (MBGN) (WHO class V). 3. A mixed GN which is a combined form of both PPGN and MBGN or mixed SLE GN (MXGN). The parameters to separate these basic groups are the immune complexes. 4. In addition there is a rare, fourth group (rare) of SLE nephritis, this has no glomerular component (interstitial nephritis, thrombotic micro agiopathy, vasculitis).

C. Based on the size, location, quantity and aggressivity of the immune complexes, PPGN may be separeted in three grades:

• 1. PPGN grade I: Has the lowest aggressivity, corresponding to WHO mesangial GN (classes IB, II).
• 2. PPGN grade II: With moderate aggressivity, corresponding to WHO focal GN (class III).
• 3. PPGN grade III: With highest aggressivity, corresponding to WHO diffuse GN (class IV).

MBGN has two grades:

• 1. MBGN grade I: Pure membranous GN, corresponding to WHO Class V A.
• 2. MBGN grade II: Membranous GN with mesangial deposits. WHO class VB has mesangial proliferation with no mention of deposits.
• 3. The mixed form (MXGN) (WHO has no class for this GN), must be graded according to the PPGN component (grades I-III).
• 4. SLE nephritis without GN can be also graded according to their aggressivity (grade I mild, grade II moderate and grade III severe).

D. Complications are inconstant lesions superimposed on any of the previous groups of GN. These complications are more frequent and more numerous in the more aggressive forms. These complications may be active lesions (WHO active lesions) or chronic lesions (WHO sclerosing lesions).
There are also non-SLE super imposed lesions, not considered by WHO (ischemic sclerosis, FSGS, diabetic glomerulosclerosis, infections, others).

There are two parameters to be considered in grading active lesions (activity): the aggressivity of the lesion and its extent. Some lesions are reversible, self-limiting and do not leave scar nor abnormal function (effacement of podocytes, necrosis of tubular cells). Other lesions may or may not be reversible, may or may not leave scars and/or abnormal function (endothelio-mesangial cell proliferation, inflammation). Still other lesions are irreversible, leave scars and abnormal function (necrosis, crescents, thrombosis). This parameter must be balanced with the extent of the active lesion. The extent of the lesion, involvement of glomeruli or renal parenchyma may be: focal (< 25%), limited (26-50%) or diffuse (> 50%). The assessment of activity is rather subjective since aggressiveness of the lesion must be balanced with the extent of the lesion to obtain the grade of activity. This grade of activity may be: 0 none, 1 mild, 2 moderate or 3 severe. We use Arabic numbers (0-3) for the grades and stages of the complications to avoid confusion with the grading of the basic lesions that have Roman numbers (0-III). Chronic lesions are measured by their extent only since most of them (if not all) are irreversible, most are scars and produce abnormal function. The chronic lesion may not be present, stage 0. They may be in an early stage of progression (<25 % involvement of glomeruli or cortical parenchyma) or stage 1. They may be in an intermediate stage (26-50%) or stage 2. Or they may be in an advanced stage (> 50%) or stage 3. Non-SLE lesions (complications) may also be graded and staged by the same parameters.

See page # 2 for the format used as a check list.

E. DEFINITIONS:

• PPGN: This new term complements the non-specific term of glomerulonephritis by WHO. The term "proliferative GN" should not be used for the basic lesions of SLE since cell proliferation is a non-specific complication that is not always present.
• MGBN: Membranous GN. The deposits are sub epithelial, global, diffuse and continuous like rosary beads. Scattered, segmental sub epithelial deposits are also present in PPGN and may be difficult to classify.
• MXGN: Mixed (MBGN and PPGN) SLE GN. The MBGN component is at times difficult to separate. Doubtful cases with subendothelial deposits should be labeled as PPGN.
• MPGN: Membranoproliferative GN (GBM reduplication), is the result of sub endothelial deposits. Therefore the presence of MPGN should be used as a sign of sub endothelial deposits.
• SIGP: Superimposed nephropathy, other than SLE (diabetic glomerulosclerosis, infection, ischemic nephrosclerosis and others).
• AC: Active complications. CC: Chronic complications. EGSLE: Extra glomerular SLE. oWHO: World Health Organization. oGBM: Glomerular basement membrane. *TBM: Tubular basement membrane. ATN: Acute tubular necrosis.

E. References:

1. Association of Directors of Anatomic and Surgical Pathology: Standardization of the Surgical Pathology Report. Am J Surg Pathol 16:84-86, 1992.

2. E.O. Hoffmann: Una Clasificacion Practica para la Nefritis Lupica. Cin2000.

3. Check List for SLE Renal Biopsies. Assessment of Activity and Chronicity. Cin2000. http://www.uninet.edu/cin2000.