Lymph node pathology

Overview in a table

Entity	Key feature	Other findings	IHC	DDx	Image
Non-specific reactive follicular hyperplasia (NSRFH)	large spaced cortical follicles	tingible body macrophages, normal dark/light GC pattern	BCL2 -ve	infection (Toxoplasmosis, HIV/AIDS), Hodgkin's lymphoma	image ?
Toxoplasmosis	large follicles; epithelioid cells perifollicular & intrafollicular	reactive GCs, monocytoid cell clusters, epithelioid cells	IHC ?	NSRFH, HIV/AIDS, Hodgkin's lymphoma	image ?
Kikuchi disease (histiocystic necrotizing lymphadenitis)	No PMNs	histiocytes, necrosis	IHC neg. for malignancy	SLE (has (blue) hematoxylin bodies in necrotic areas)	[1]
Cat-scratch disease	PMNs in necrotic area	"stellate" (or serpentine) shaped microabscesses, granulomas	B. henselae, Dieterle stain	HIV/AIDS, NSRFH	[2]
Dermatopathic lymphadenopathy	melanin-laden histiocytes	histiocytosis	S100+ve (interdigitating dendritic cells), CD1a+ve (Langerhans cells)	DDx ?	image ?
Kimura disease	eosinophils	angiolymphoid proliferation	IHC ?	eosinophilic granuloma	[3]
Langerhans cell histiocytosis	abundant histiocytes with reniform nuclei	often prominent eosinophilia	S100+, CD1a+	Kimura disease (eosinophilia), Rosai-Dorfman disease	[4]
Rosai-Dorfman disease	sinus histiocytosis	emperipolesis	S100+, CD1a-	Langerhans cell histiocytosis	[5]
Systemic lupus erythematosus lymphadenopathy	(blue) hematoxylin bodies	necrosis, no PMNs	IHC ?	Kikuchi disease	image ?

Factors to consider:^[1]

	Reactive follicular hyperplasia	Follicular lymphoma
Follicle location	cortex	cortex and medulla
Germinal center edge	sharp/well-demarcated	poorly demarcated
Germinal center density	well spaced	crowded
Tingible body macrophages	common	uncommon
Germinal center light/dark pattern	normal	abnormal