Kaposi’s sarcoma is a relatively rare, malignant tumor characterized by spindle cell proliferation and angiomatous structures, and its development may be associated with infection by a herpes-like virus (HHV-8). Dermoscopically Kaposi’s sarcoma has several features: 1) dark purplish-blue surface; 2) scaly surface; 3) brown vesicles, etc. These features may also be seen in other skin tumors and are relatively non-diagnostic. However, in some areas, dermatoscopy can observe the phenomenon of multiple colors coming together like a rainbow, and we name this feature as rainbow features. Usually the color of the tumor seen by dermatoscopy does not differ much from the color seen by the naked eye, but we found that some parts of Kaposi’s sarcoma appeared in a rainbow of colors on dermatoscopy, a phenomenon we had not seen before. Later, we observed several other Kaposi’s sarcoma patients and found that some of their lesions also appeared iridescent on dermatoscopy. We also found that the vascular structures underneath the lesions were denser in the areas where rainbow features were present and sparser in the areas where there were no rainbow features. Therefore, the rainbow phenomenon may be associated with the dense vascular structure underneath the lesions in some areas of Kaposi’s sarcoma. Over the years, we have used dermatoscopy to observe various skin tumors other than Kaposi’s sarcoma, including cutaneous hemangioma, melanoma, basal cell tumor, squamous cell tumor, etc., but no rainbow features were found in these tumors, so the rainbow features are likely to be a specific dermatoscopic feature unique to Kaposi’s sarcoma.