Histologic findings of poorly differentiated cluster and tumor budding of IDC-NOS. Cancer nests in the stroma, which do not show gland-like structures and are composed of up to five cancer cells, were defined as PDCs (indicated by yellow arrows. (A) 20×; (B) 40×; (C) 100×). Single cancer cells or clusters of fewer than five cancer cells were defined as tumor budding (indicated by black arrows. (D) 20×; (E) 40×; (F) 100×). Both PDC grade and tumor budding are determined from histological findings (E,F).