Vascular neoplasms of the lower limbs: similar clinical presentation, distinct prognoses

César Silva-Ferreira, Unidade Local de Saúde Santo António, Serviço de Dermatovenereologia, Hospital de Santo António, Porto, Portugal Marco Sousa, Unidade Local de Saúde Santo António, Serviço de Dermatovenereologia, Hospital de Santo António, Porto, Portugal Diana Bernardo, Unidade Local de Saúde Santo António, Serviço de Dermatovenereologia, Hospital de Santo António, Porto, Portugal André Coelho, Department of Pathological Anatomy. Centro Hospitalar Universitário de Santo António, Porto, Portugal Gloria da Cunha-Velho, Unidade Local de Saúde Santo António, Serviço de Dermatovenereologia, Hospital de Santo António, Porto, Portugal Mónica Caetano, Unidade Local de Saúde Santo António, Serviço de Dermatovenereologia, Hospital de Santo António; Department of Dermatology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto. Porto, Portugal

Angiosarcoma and classic Kaposi sarcoma are vascular neoplasms that may present with similar clinical features but have distinct prognoses and therapeutic implications. We describe two patients presenting with violaceous plaques and nodules on the lower extremities. Histopathological evaluation was essential for the differential diagnosis. In the first case, a high-grade epithelioid endothelial proliferation was observed, showing marked atypia, frequent mitoses, positivity for ETS-related gene, and negativity for human herpesvirus 8 (HHV-8), consistent with cutaneous angiosarcoma. In the second case, a spindle-cell vascular proliferation with irregular, thin-walled vessels and HHV-8 positivity was identified, confirming Kaposi sarcoma. Despite clinical similarity, angiosarcoma exhibits aggressive behavior and carries a poor prognosis, whereas classic Kaposi sarcoma typically follows an indolent course. Early biopsy with immunohistochemical characterization is essential for accurate diagnosis and appropriate therapeutic guidance.

Keywords: Angiosarcoma. Kaposi sarcoma. Vascular neoplasms. Human herpesvirus 8. Immunohistochemistry.