Kaposi sarcoma: immunohistochemical study of some diagnostic and prognostic markers

Background Kaposi sarcoma (KS) poses problems in a histologic diagnosis because of its broad morphologic spectrum and of its similarity to many benign vasoproliferative lesions. The variability in the biologic behavior of KS among individuals in the same group remains enigmatic. Objective To evaluate the role of latent nuclear antigen-1 of human herpes virus-8 (HHV-8 LNA-1), CD31, and CD34 as diagnostic markers in classical cutaneous KS and its mimickers. Cyclin D1, p27Kip1, Ki-67, p53, and Bcl-2 were also evaluated as prognostic markers in classical cutaneous KS. Patients and methods The present study included a total of 42 patients: 15 cases of classical cutaneous KS (HIV negative) and 27 cases of its mimickers. KS patients were classified into two groups: group I included seven patients in the patch/plaque stage and group II included eight patients in the nodular stage. Using immunohistochemistry, we tested HHV-8 LNA-1, CD31, and CD34 in classical cutaneous KS and its mimickers and cyclin D1, p27Kip1, Ki-67, p53, and Bcl-2 only in the tissue of those with classical cutaneous KS. Results CD31 and CD34 positivities were found in all cases of KS and also in other mimickers, but with variable intensity. All KS cases showed positive staining for HHV-8 LNA-1 (100%), but KS mimickers were all negative for this antigen. The intensity of expression for cyclin D1, p53, and Bcl-2 showed a statistically significant increase in group II than group I (P = 0.007, 0.006, and 0.0005, respectively). The expression of p27Kip1 showed a statistically significant increase in group I than group II (P = 0.002). The intensity of expression for Ki-67 showed no statistically significant difference between the two groups (P= 0.489). Conclusion Positive immunostaining for HHV-8 LNA-1 exhibits 100% sensitivity and specificity for the diagnosis of KS patients and is thus useful for distinguishing it from the mimickers. Cyclin D1, p53, and Bcl-2 were highly expressed in the nodular stage compared with the early stage (patch/plaque), whereas p27Kip1 was highly expressed in the early stage (patch/plaque) compared with the tumor stage.