This video presents a detailed pathological examination of a recurrent nodule in the ear canal of a 33-year-old male. The key finding is the diagnosis of Angiolymphoid Hyperplasia with Eosinophilia (ALHE), which the speaker notes is recommended to be renamed Epithelioid Hemangioma according to the 2020 WHO classification. The lesion is characterized by a lobular proliferation of blood vessels lined by plump epithelioid endothelial cells, accompanied by a brisk inflammatory infiltrate rich in lymphocytes and eosinophils. The speaker highlights "Wolverine sign" streaks in the gross specimen, suggesting the presence of something hard (like bone or calcium) that scratched the tissue during the previous excision. Differential diagnoses considered and ruled out include Kaposi sarcoma and angiosarcoma. Immunohistochemical staining (CD31 and ERG) is used to beautifully delineate the vascular channels and confirm the benign nature of the lesion, emphasizing that diffuse, blazing positivity seen in malignancy (like angiosarcoma) is absent here. The speaker also cautions against confusing Epithelioid Hemangioma with the malignant Epithelioid Hemangioendothelioma due to their similar names.
Pathology Deep Dive: Angiolymphoid Hyperplasia with Eosinophilia (Epithelioid Hemangioma)
0:00 Recurrent Nodule: The case involves the re-excision of a 33-year-old male's ear canal nodule, which had previously recurred.
0:00 "Wolverine Sign": Visible streaks on the excised tissue suggest trauma from a hard element (likely bone or calcium) during the initial surgery.
0:01:08 Histology of the Nodule: The primary lesion shows a cellular, lobular proliferation of vessels with plump endothelial cells; some areas lack visible lumens, potentially mimicking aggressive tumors.
0:01:34 Differential Diagnosis Considered: Initial morphology raises concerns for Kaposi sarcoma or subtle angiosarcoma due to cellularity and occasional mitotic figures.
0:02:08 Inflammatory Background: A crucial finding is the background mixed lymphocytic infiltrate with scattered eosinophils, which points toward ALHE.
0:02:29 Diagnosis: ALHE/Epithelioid Hemangioma: The diagnosis is Angiolymphoid Hyperplasia with Eosinophilia (ALHE), now recommended to be called Epithelioid Hemangioma (EH) in the 2020 WHO classification.
0:03:01 Neoplastic Nature: The speaker notes that these lesions are likely true neoplasms, often associated with $FOS$ or $FOSB$ gene fusions in about 50% of cases.
0:04:26 Nomenclature Warning: Caution is stressed to differentiate Epithelioid Hemangioma (benign vascular lesion) from the malignant Epithelioid Hemangioendothelioma, as the names sound similar and can cause confusion during literature searches.
0:05:18 Vacuoles in Endothelial Cells: Cytoplasmic vacuoles in epithelioid endothelial cells are common in ALHE/EH, but are not specific, also appearing in Epithelioid Hemangioendothelioma and sometimes angiosarcoma.
0:06:15 Genetic Marker Potential: The speaker mentions a paper suggesting that $FOS/FOSB$ expression may link unusual variants of inflammatory hemangiomas to the ALHE spectrum.
0:06:55 Immunohistochemistry Utility: Vascular markers (CD31, ERG) are used to clarify the architecture, showing well-formed, lobular vessels rather than infiltrative growth seen in angiosarcoma.
0:08:31 Histiocyte Staining on CD31: The speaker notes that weak, granular CD31 staining on background histiocytes should not be mistaken for strong, diffuse endothelial staining indicative of malignancy.
0:09:11 Rule for Malignancy Markers: If the expression of vascular markers is questionable ("if you have to ask yourself if it's enough the answer is probably no"), it is generally not solid blazing expression typical of angiosarcoma.
0:10:25 Benign Behavior: Epithelioid Hemangioma is benign, although it can be multifocal, multinodular, and locally recurrent.