This pathology video presents a case study of a recurrent violaceous nodule in the ear canal of a 33-year-old male, initially excised years prior. The key diagnostic clue is the "Wolverine sign"—streaks in the tissue suggesting scratching by a hard object, prompting a search for bone or calcified material near the mastoid bone. Histologically, the nodule is characterized by a cellular, lobular proliferation of vessels with plump endothelial cells, raising concerns for vascular malignancies like angiosarcoma or Kaposi sarcoma. However, the presence of mixed lymphocytic infiltrates and abundant eosinophils, along with epithelial cells bulging into the lumen, confirms the diagnosis of Angiolymphoid Hyperplasia with Eosinophilia (ALHE), which the 2020 WHO classification recommends renaming Epithelial Hemangioma. The presenter notes that about 50% of cases involve FOS or FOSB gene fusions, supporting their neoplastic nature. The video emphasizes differentiating ALHE from more aggressive entities like Epithelioid Hemangioendothelioma (EHE) and angiosarcoma, particularly due to confusing nomenclature and the presence of cytoplasmic vacuoles in endothelial cells. Immunohistochemistry (using CD31 and ERG) is used to illustrate the organized, well-formed vascular channels typical of ALHE, contrasting them with the invasive pattern of angiosarcoma, and highlighting that diffuse, blazing CD31 positivity is suggestive of malignancy, whereas granular CD31 staining in histiocytes is a common finding.
Analyzing Angiolymphoid Hyperplasia (Epithelial Hemangioma) of the Ear Canal
00:00:09 Case Presentation: A recurrent, violaceous nodule in the ear canal of a 33-year-old male, necessitating re-excision near the mastoid bone.
00:00:16 "Wolverine Sign": Streaks in the tissue suggest trauma from a hard object (like bone or calcium), prompting the surgeon's attention.
00:01:10 Histopathology Findings: The lesion shows a cellular, lobular proliferation of vessels with plump endothelial cells, initially raising concern for Kaposi sarcoma or angiosarcoma.
00:02:15 Inflammatory Component: Background shows mixed lymphocytic infiltrates and scattered eosinophils, a key feature pointing toward the diagnosis.
00:02:29 Diagnosis Confirmation: The diagnosis is Angiolymphoid Hyperplasia with Eosinophilia (ALHE), now recommended to be called Epithelial Hemangioma (per the 2020 WHO classification).
00:03:01 Neoplastic Nature: ALHE/Epithelial Hemangioma is likely a true neoplasm, with approximately 50% of cases showing FOS or FOSB gene fusions.
00:04:26 Naming Confusion Warning: Crucial distinction made between Epithelial Hemangioma (benign ALHE) and the potentially more aggressive Epithelioid Hemangioendothelioma (EHE), which are easily confused by non-experts.
00:05:27 Cytoplasmic Vacuoles: Plump epithelioid endothelial cells with cytoplasmic vacuoles are common in ALHE, EHE, and even angiosarcoma; vacuoles alone do not confirm EHE.
00:06:15 Prior Diagnosis: The patient's previous excision was already diagnosed as ALHE/Epithelial Hemangioma.
00:07:16 Immunohistochemistry Utility: Vascular markers (like CD31) can confirm the well-formed, lobular architecture, distinguishing it from infiltrating/anastomosing patterns seen in angiosarcoma.
00:08:31 CD31 Staining Interpretation: Endothelial cells stain strongly (Level 11), while background histiocytes stain weakly granular (Level 3) with CD31—this distinction prevents misinterpreting background inflammation as extensive vascular proliferation.
00:09:11 Rule for Malignancy: If a pathologist must question whether the CD31 staining is "enough" to suggest angiosarcoma, the answer is usually no; angiosarcoma typically shows "solid blazing wall-to-wall expression."
00:10:25 Prognosis: Epithelial Hemangioma (ALHE) is benign but can be multifocal, multinational, and locally recurrent.