Practical Application of Columbia Classification for Focal Segmental Glomerulosclerosis

Area of Science:

• Nephrology
• Pathology
• Histopathology

Background:

• Focal segmental glomerulosclerosis (FSGS) is a complex kidney disease with varied causes and appearances.
• Existing classification systems include etiological (genetic, adaptive, viral, drug-induced, idiopathic) and morphological approaches.
• The Columbia classification, based on light microscopy, identifies five variants: collapsing, tip, cellular, perihilar, and not otherwise specified (NOS).

Purpose of the Study:

• To define common histopathological features of FSGS.
• To differentiate the distinct characteristics of the five FSGS variants.
• To address terminological confusion and application challenges of the Columbia classification.

Main Methods:

• Review of histopathological features of FSGS.
• Analysis of the diagnostic criteria for the five Columbia classification variants.
• Examination of interobserver reproducibility and application difficulties.

Main Results:

• The Columbia classification provides a standardized approach to FSGS diagnosis and prognosis.
• Key histopathological differences exist among the collapsing, tip, cellular, perihilar, and NOS variants.
• Challenges include interpreting mixed variant lesions and the evolution of variants into NOS over time.

Conclusions:

• The Columbia classification is a valuable diagnostic and prognostic tool for FSGS.
• Clarifying variant terminology and addressing interpretation challenges are crucial for consistent application.
• Further research may refine understanding of lesion evolution and mixed features in FSGS.