The correct answer is D. Metaplasia
The pathologist has found an example of metaplasia, which is characterized by one adult cell type being replaced by another cell type. This change is reversible. Normal bronchi are lined with pseudostratified, columnar, ciliated epithelium. Squamous epithelia in the bronchi are not normal and are often a sign of environmental exposure and/or irritation (i.e., smoking).
Answer A is incorrect. Anaplasia, an irreversible change, describes abnormal cells lacking differentiation. Anaplasia is not the answer, since the squamous cells appear organized and differentiated, although they are in an abnormal location.
Answer B is incorrect. Dysplasia is abnormal growth with loss of cellular orientation, shape, and size in comparison to normal tissue maturation. Dysplasia is not the answer, since the squamous cells appear organized and differentiated, although they are in an abnormal location.
Answer C is incorrect. Hyperplasia is an in- crease in number of the normal cell type.
Answer E is incorrect. Neoplasia describes a clonal proliferation of cells that is uncontrolled and excessive, and in this case the growth is confined above the basement membrane. There is no sign of metastasis, nor is there a sign of uncontrolled proliferation, as there are only a few layers of squamous cells. Like anaplasia, neoplasia is not reversible.