Collision of vascular malignancies: Kaposi sarcoma and spindle-cell angiosarcoma in a HIV-negative patient

Abstract

Introduction

It is very uncommon for Kaposi sarcoma (KS) and angiosarcoma (AS) to occur simultaneously at the same anatomical site, especially in immunocompetent, HIV-negative people. Due to variations in prognosis and treatment, it is crucial to identify dual vascular malignancies.

Case Presentation

A 66-year-old man presented with a large exophytic tumor of the left foot at the site of previously diagnosed KS. Amputation of the second, third, and fourth toes was necessary for surgical treatment. Malignant spindle-cell vascular proliferation with irregular slit-like spaces, prominent cellular pleomorphism, frequent mitoses, and an inflammatory infiltrate were all revealed by histopathological examination. Immunohistochemistry demonstrated strong positivity for endothelial markers, while human herpesvirus 8 (HHV-8) staining was negative in the new lesion. Clinical, histopathological, and molecular findings confirmed the presence of two distinct vascular neoplasms: the initial KS lesion was HHV-8 positive, whereas the newly developed AS was HHV-8 negative and exhibited a high proliferative index, supporting its aggressive and independent nature.

Conclusions

This case demonstrates that both KS and a distinct high-grade AS can develop in the same area in patients who are HIV-negative. Since multiple primary vascular tumours may coexist and substantially impact diagnosis, prognosis, and treatment, lesions exhibiting atypical or aggressive behaviour should prompt a thorough pathological reassessment.

Keywords: angiosarcoma, immunohistochemistry, kaposi sarcoma, vascular tumours