Endothelial cells may have cytoplasmic vacuolization
May have solid appearance
• Many eosinophils, lymphocytes, and mast cells, although eosinophil number can vary greatly
Top Differential Diagnoses
• Papillary endothelial hyperplasia
• Kimura disease
• Angiosarcoma
• Metastatic papillary thyroid carcinoma
Subepithelial Vascular Proliferation Hematoxylin and eosin shows an intact surface epithelium with a richly vascularized stroma containing lymphoid elements. Eosinophils are present, imparting a bright red appearance at this low magnification.
Vascular Proliferation With Eosinophils There are sheets of eosinophils in the background stroma. The vascular spaces are lined by endothelial cells that are enlarged and prominent. There is no atypia and no anastomosing.
High Endothelial Cells The endothelial cells are enlarged and partly occlude the lumen. Eosinophils are noted in the background. Sometimes the eosinophils are inconspicuous.
Endothelial Hyperplasia Hematoxylin and eosin shows endothelial hyperplasia with a thickened vessel wall and increased inflammatory cells, including eosinophils, in the surrounding tissue. Note the extravasated erythrocytes.
TERMINOLOGY
Abbreviations
• Angiolymphoid hyperplasia with eosinophilia
Synonyms
• Epithelioid hemangioma
• Nodular, angioblastic hyperplasia with eosinophilia and lymphofolliculosis
Definitions
• Benign vascular tumor with well-formed, immature blood vessels, most of which are lined by plump, epithelioid (histiocytoid) endothelial cells with prominent inflammatory component, especially eosinophils
ETIOLOGY/PATHOGENESIS
Reactive
• History of trauma; larger vessels show damage with prominent inflammatory component
Neoplastic
• May represent benign neoplasm, with evidence of clonal T-cell population in some cases
CLINICAL ISSUES
Epidemiology
• Age
Wide range; mean: 3rd to 5th decades
• Sex
F > M
• Ethnicity
Not increased in Asian patients (i.e., not Kimura disease)
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are enlarged and partly occlude the lumen. Eosinophils 
are noted in the background. Sometimes the eosinophils are inconspicuous.
