  Histopathological image segmentation is a laborious and time-intensive task,
often requiring analysis from experienced pathologists for accurate
examinations. To reduce this burden, supervised machine-learning approaches
have been adopted using large-scale annotated datasets for histopathological
image analysis. However, in several scenarios, the availability of large-scale
annotated data is a bottleneck while training such models. Self-supervised
learning (SSL) is an alternative paradigm that provides some respite by
constructing models utilizing only the unannotated data which is often
abundant. The basic idea of SSL is to train a network to perform one or many
pseudo or pretext tasks on unannotated data and use it subsequently as the
basis for a variety of downstream tasks. It is seen that the success of SSL
depends critically on the considered pretext task. While there have been many
efforts in designing pretext tasks for classification problems, there haven't
been many attempts on SSL for histopathological segmentation. Motivated by
this, we propose an SSL approach for segmenting histopathological images via
generative diffusion models in this paper. Our method is based on the
observation that diffusion models effectively solve an image-to-image
translation task akin to a segmentation task. Hence, we propose generative
diffusion as the pretext task for histopathological image segmentation. We also
propose a multi-loss function-based fine-tuning for the downstream task. We
validate our method using several metrics on two publically available datasets
along with a newly proposed head and neck (HN) cancer dataset containing
hematoxylin and eosin (H\&E) stained images along with annotations. Codes will
be made public at
https://github.com/PurmaVishnuVardhanReddy/GenSelfDiff-HIS.git.
