Sensitivity and specificity of D2-40 in differentiating Kaposi sarcoma from its mimickers

Abstract

Background Kaposi sarcoma (KS) is a low-grade malignant vascular neoplasm, whose etiology is associated with human herpes virus 8 (HHV8). Owing to its broad clinicopathological spectrum, KS mimics a variety of non-KS vascular lesions both clinically and histologically, thus posing a diagnostic challenge. Immunohistochemical markers are needed to confirm diagnosis. Objective To study the sensitivity and specificity of D2-40 in comparison with HHV8-latent nuclear antigen 1 to identify KS among other cutaneous vascular proliferative lesions. Patients and methods The present study was carried out on 50 cases with cutaneous vascular proliferation. Examination of hematoxylin and eosin-stained sections was done for all cases to verify the diagnosis. Additional sections of all cases were subjected to immunohistochemical stains for the following primary antibodies: HHV8 and D2-40 monoclonal antibody. Results The study included 19 KS cases and 31 non-KS. Among KS lesions 15.8% were patch stage, 26.3% plaque stage, 36.84% nodular stage, 10.5% pyogenic granuloma-like KS, and 10.5% intravascular KS. All KS cases stained positive for HHV8-latent nuclear antigen 1, whereas none of other vascular lesions showed positive staining. Immunohistochemistry using D2-40 showed positive staining in 70% (n=35) and negative staining in 30% (n=15) of the total cases. All KS lesions expressed D2-40 in both endothelial lining and spindle cells. A total of 16 cases of non-KS vascular lesions expressed D2-40 in endothelial lining only. D2-40 positivity of both endothelial lining and spindle cells was found to be equally sensitive and specific to HHV8 for diagnosis of KS. Conclusion D2-40 positivity of both vascular lining and spindle cells can be considered both sensitive and specific stain to differentiate KS from other vascular lesions.