Lymphangioma-like Kaposi Sarcoma: Challenges in Differential Diagnosis

Background. Kaposi’s sarcoma (KS) is a multifocal vascular neoplasia with uncertain histogenesis, characterized by angioproliferative multifocal tumors affecting mainly the skin. The “lymphangioma-like” or “bullous KS” variant is a rare morphologic expression of KS, accounting for less than 5% of all cases and appearing among all KS epidemiological subtype. This review provides a comprehensive overview of clinical and pathological characteristics of patients with lymphangioma-like Kaposi’s sarcoma LLKS. Methods. We included 93 patients with Kaposi sarcoma, aged between 36 and 90 years; diagnosis was made as a result of the histopathological examination. The surgical excision samples were fixed in 10% buffered formalin, paraffin embedded and stained with Hematoxylin-Eosin for histopathological examination. Immunohistochemical staining was performed using the following antibodies: CD34, CD31, actin, myoglobin, desmin, cytokeratin and vimentin. Results. The histological features of LLKS vary considerably from the traditional KS, classic KS areas have been absent from some lymphangioma-like KS. Most of the patients were diagnosed in nodular stage and confirmed by positive immunohistochemical staining. Clinically, each patient presented with violaceous patches, papules or plaques; some of the patients presented with bullous lesions. All tumour cells, including those associated with LLKS foci, showed a strong and diffuse reactivity for anti-HHV-8 LNA-1and anti-CD34. Conclusions. Differential diagnosis of lymphangioma-like Kaposi’s sarcoma LLKS with other vascular tumors may be very difficult and a detailed histologic study in combination with immunohistochemistry, such as staining for HHV-8 latent nuclear antigen, is essential for correctly diagnosing lymphangioma-like KS.