PathView-Bench: Can Multimodal Large Language Models Achieve Fine-grained Multiscale Understanding of Pathology Images?

Multimodal large language models (MLLMs) are increasingly used to analyze pathology images. However, dominant multimodal benchmarks in pathology mainly score final diagnostic answers, captions, or reports. These evaluations provide limited insight into whether a model understands the multiscale visual content needed for pathology reasoning and decision-making. We introduce PathView-Bench, a vision-anchored benchmark for fine-grained and multiscale visual understanding in computational pathology. Built from $23$ public pathology imaging datasets with human-supervised labels and spatial annotations, PathView-Bench evaluates MLLM understanding in two fields of view: Region-FOV for high-resolution local regions and Slide-FOV for macro whole-slide views. By converting raw annotations into deterministic task targets, PathView-Bench enables programmatic scoring of region localization, visual recognition, quantity estimation, spatial reasoning, and insufficient-context judgment. The benchmark contains $14$ VQA-style tasks, $61,673$ images, and $308,070$ samples across $28$ organs and $7,253,526$ annotations. Evaluating $18$ representative general-purpose, medical-domain, and pathology-oriented MLLMs, we observe substantial limitations even in advanced models on fine-grained visual tasks across multiscale pathology images. PathView-Bench provides a reproducible basis for developing and evaluating pathology MLLMs with explicit multiscale visual understanding.