MUC5AC and neoplasm: Complete response: any of the following features with no residual tumor cells: the presence of foamy or hemosiderin-laden macrophages with or without dystrophic calcification, (ii) lakes of acellular mucin, and/or (iii) the presence of substantial fibrosis or tumor necrosis; partial response: with features of nodal regression and persistent tumor cells; no response: with LN metastasis but no features of regression