CD30 expression in malignant vascular tumors and its diagnostic and clinical implications: a study of 146 cases
Angiosarcoma (AS) is a rare malignant vascular tumor, whereas epithelioid hemangioendothelioma (EHE) is a vascular tumor of low-grade malignancy. CD30 is a member of the tumor necrosis factor receptor superfamily, member 8 (TNFRSF8). Although the expression of CD30 is most commonly associated with lymphoid malignancies or germ cell tumors, occasional ASs have been reported as CD30 positive. However, there are limited data to evaluate its role definitively in malignant vascular tumors. In this study, we evaluated 91 ASs, 30 EHEs from various sites, and 25 Kaposi sarcomas. Overall, CD30 was expressed in 31/91 cases (34%) of AS, in 7/30 cases (30%) of EHE, but in none of the Kaposi sarcomas. CD30 was expressed in a membranous staining pattern and positivity in tumor cells varied from focal to diffuse. The positive ASs included vasoformative more differentiated tumors and also solid, undifferentiated, lymphoma-like examples, one of which was classified as lymphoma before the era of immunohistochemistry. The CD30 expression was seen in >50% of tumor cells in a majority of ASs but only in 7% of EHEs. None of the 55 ASs studied were immunohistochemically positive for TIA-1 or Granzyme B, antigens used as more specific markers for anaplastic large-cell lymphoma. Compared with AS, normal vascular endothelia of capillaries and muscular vessels showed variable positivity. Among hemangiomas, cavernous and spindle cell hemangiomas showed most frequent endothelial CD30 positivity, whereas in most other hemangiomas, CD30 positivity was scant. In conclusion, CD30 expression occurs in a significant subset of ASs and EHEs and needs to be included in the differential diagnosis with other CD30-positive malignancies to avoid a diagnostic pitfall. It remains to be determined whether patients with strongly CD30-positive ASs could be candidates for targeted therapy using the recently introduced CD30 antibody drug conjugates.