Distinct patterns of cells with heterogenous HER2 status include “clustered” type, featuring the presence of two topographically distinct tumor clones of tumor cells, one harboring HER2 amplification and the other with normal HER2 status; “mosaic” type, displaying either diffuse intermingling of cells with different HER2 statuses; and “scattered type”, with isolated HER2-amplified cells in a HER2-negative tumor cell population23–25. The gene discussed is ERBB2; the disease is neoplasm.