A lymph node biopsy from a patient shows follicular hyperplasia with germinal centres containing tingible body macrophages. These macrophages appear starry against a dark background (starry sky pattern). The dark background cells are:

• A Plasma cells secreting high-affinity immunoglobulin
• B Follicular dendritic cells forming the antigen-presenting mesh
• C Centrocytes and centroblasts (B cells in various stages of germinal centre reaction) ✓
• D T follicular helper cells directing B-cell class switching

Explanation

In reactive follicular hyperplasia, the germinal centres contain a mixture of centrocytes (small, cleaved B cells undergoing selection) and centroblasts (large, non-cleaved rapidly dividing B cells). Tingible body macrophages phagocytose apoptotic cells (bodies), appearing as pale macrophages on a dark background of densely packed, dark-staining centroblasts and centrocytes. This creates the 'starry sky' pattern when the pale macrophages stand out against the dark lymphocytic background. Plasma cells are found in the marginal zone/red pulp, not prominently in germinal centres. Follicular dendritic cells are the stromal mesh; TFH cells are a minor population.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.