  Digital pathology has become a standard in the pathology workflow due to its
many benefits. These include the level of detail of the whole slide images
generated and the potential immediate sharing of cases between hospitals.
Recent advances in deep learning-based methods for image analysis make them of
potential aid in digital pathology. However, a major limitation in developing
computer-aided diagnostic systems for pathology is the lack of an intuitive and
open web application for data annotation. This paper proposes a web service
that efficiently provides a tool to visualize and annotate digitized
histological images. In addition, to show and validate the tool, in this paper
we include a use case centered on the diagnosis of spindle cell skin neoplasm
for multiple annotators. A usability study of the tool is also presented,
showing the feasibility of the developed tool.
