OODML: Whole Slide Image Classification Meets Online Pseudo-Supervision and Dynamic Mutual Learning

Bag-label-based multi-instance learning (MIL) has demonstrated significant performance in whole slide image (WSI) analysis, particularly in pseudo-label-based learning schemes. However, due to inaccurate feature representation and interference, existing MIL methods often yield unreliable pseudo-labels, which spawn undesired predictions. To address these issues, we propose an Online Pseudo-Supervision and Dynamic Mutual Learning (OODML) framework that enhances pseudo-label generation and feature representation while exploring their mutual learning to improve bag-level prediction. Specifically, we design an Adaptive Memory Bank (AMB) to collect the most informative components of the current WSI. We also introduce a Self-Progressive Feature Fusion (SPFF) module that integrates label-related historical information from the AMB with current semantic variations, thereby enhancing the representation of pseudo-bag tokens. Furthermore, we propose a Decision Revision Pseudo-Label (DRPL) generation scheme to explore intrinsic connections between pseudo-bag representations and bag-label predictions, resulting in more reliable pseudo-label generation. To alleviate redundant and ambiguous representations, the class-wise prior of pseudo-label prediction is borrowed to facilitate label-related feature learning and to update the AMB, forming a mutual refinement between feature representation and pseudo-label generation. Additionally, a Dynamic Decision-Making (DDM) module is developed to harmonize explicit and implicit representations of bag information for more robust decision-making. Extensive experiments on four datasets demonstrate that our OODML surpasses the state-of-the-art by 3.3% and 6.9% on the CAMELYON16 and TCGA Lung datasets.