Reactive Conditions of the Lymph Node

(This is a continuation of the notes I have taken from the Sabah Lymphoma talk)

I. Lymphadenopathies
Lymphadenopathies are divided into three:
1. Reactive lymphoid hyperplasia
2. Atypical lymphoid hyperplasia
3. Progressive transformation of germinal centre

1. Reactive lymphoid hyperplasia

• Has a follicular pattern OR may present as diffuse paracortical hyperplasia.
• Characteristics: architecture preserved, capsule intact, enlarged germinal centre, mitotically active, tingible body macrophages, mantle zone present.
• Main differential of follicular pattern: follicular lymphoma.

2.  Progressive transformation of germinal centre

• Mainly in adolescent males.
• Numerous follicules in different stages with follicular hyperplasia.
• Late stage: small lymphocytes infiltrating germinal centres, germinal centre disrupted.

II. Castleman's disease

1.  Hyaline vascular variant

• Can be unilocular or multiple places.
• Numerous follicles with small germinal centre, onion-skin pattern of mantle zone.
• Hyaline deposit in germinal centre.
• Lollipop sign - when blood vessel enters the follicles
• Twinning of germinal centre (eg 1 follicle contains 2 germinal centres.
• Prominent blood vessels (with plump endothelial cells) surrounded by eosinophils and lymphocytes.
• It may involve only 1-2 follicles
• May see cracking artefact around the follicles.

2.  Plasma cell variant

• Reactive follicles with interfollicular plasmacytosis.
• Germinal centre penetrated by prominent blood vessels.
• Sheets of mature plasma cells.

III. Rosai-Dorfman disease

• Greatly expanded sinuses filled by foamy macrophages and histiocytes with lymphocytes and plasma cells.
• Emperipolesis: lymphocytes in macrophages.

IV. Kikuchi disease

• Self-limiting, typically young Asian females.
• Unwell for a few weeks to months.
• Loosely cohesive granulomatous nodules in paracortex with 'blastic' macrophages.
• Presence of central necrosis.
• Absence of lymphocytes and neutrophils at the necrotic centre.
• Immunohistochemistry: macrophages are positive for MPO and negative for CD20 and CD3.

V. Sarcoidosis

• Non-caseating granuloma.
• Lymph node: architecture partially or totally replaced.

VI. Systemic Lupus Lymphadenopathy

• Site: usually cervical, generalised.
• Associated with active disease.
• Histology: necrosis surrounded by histiocytes with paracortical hyperplasia.  Also presence of nuclear dust and basophilic haematoxylin bodies.