This video provides a detailed microscopic examination of Angiolymphoid Hyperplasia with Eosinophilia (ALHE), also known as Epithelioid Hemangioma (EH). The discussion highlights the classic low-power presentation, often involving large vessels, most commonly the temporal artery or its branches. Morphologically, the lesion features lobules of vessels lined by characteristic plump, epithelioid endothelial cells, frequently pushing into and obscuring the lumens. A brisk inflammatory infiltrate of lymphocytes (sometimes forming germinal centers) and numerous eosinophils is typically present, though the speaker notes that inflammation can be sparse in some cases. A critical diagnostic pitfall discussed is the atypical, highly cellular variant occurring in the penis, which may be mistaken for angiosarcoma, underscoring the need for careful consultation in such scenarios.
Angiolymphoid Hyperplasia with Eosinophilia (ALHE) / Epithelioid Hemangioma (EH)
0:18 Classic Presentation: The featured case is a "very nice example" of Angiolymphoid Hyperplasia with Eosinophilia (ALHE), characterized by a distinct low-power appearance.
0:37 Nomenclature and Etiology: ALHE is also known as Epithelioid Hemangioma (EH). Current knowledge suggests a potential division between true neoplastic EH (often having FOS/FOSB abnormalities) and reactive skin lesions with prominent vessels, lymphocytes, and eosinophils.
1:18 Common Location: The tumor often arises in or expands from a damaged vessel, commonly the temporal artery or its branches.
1:45 Endothelial Morphology: The endothelial cells are very plump, large, and "epithelioid," often pushing into and obscuring the vessel lumens, sometimes appearing more like nests of cells.
2:41 Endothelial Vacuoles: The plump endothelial cells frequently exhibit cytoplasmic vacuoles (endothelial vacuoles), a feature common in epithelioid vascular lesions (including EH, Epithelioid Hemangioendothelioma, and Spindle Cell Hemangioma).
3:15 Inflammatory Background: There is a brisk inflammatory background featuring numerous lymphocytes (sometimes forming germinal centers, with large atypical B cells and CD30 positive immunoblasts) and abundant eosinophils.
4:03 Important Caveat: While the presented case is robustly lymphoid, some cases of ALHE/EH have very sparse inflammation and only scattered eosinophils.
4:40 Critical Diagnostic Pitfall (Penis): EH of the penis can be very cellular and atypical, potentially leading to misdiagnosis as angiosarcoma. The speaker advises seeking consultation before diagnosing angiosarcoma in this location due to the dramatic patient consequences.
5:20 Molecular Markers: FOS or FOSB staining is noted as potentially useful for diagnosis, as these lesions are part of a growing number of endothelial lesions related to FOS/FOSB fusions or immunostaining.
6:00 Differential Diagnosis (Kimura Disease): Kimura disease is generally considered a hematopathology disease and is thought to have a greater lymph node predominance and potentially more neutrophils compared to ALHE/EH.