The cells showing intense pink cytoplasmic staining are most likely which cell type?

• A. Plasma cells
• B. Lymphocytes
• C. Erythrocytes
• D. Neutrophils

Answer: (A)

Intense pink staining of the cytoplasm points to a cell with a cytoplasm rich in proteins and secretory machinery. Plasma cells fit this description best because they are antibody-secreting B cells that invest a lot of cytoplasm with rough endoplasmic reticulum and Golgi apparatus to produce and process proteins. That abundance of protein-rich cytoplasm takes up eosin dye readily, giving a bright pink appearance, and these cells are typically large with an eccentrically placed nucleus, a combination that helps them stand out on stained sections.

Lymphocytes have very little cytoplasm, so they don’t show that bright pink cytoplasmic halo. Erythrocytes are anucleate and appear pink as they are filled with hemoglobin, but they aren’t the large, protein‑rich, antibody‑secreting cells that leave a prominent eosinophilic cytoplasm. Neutrophils contain granules that can appear pink, but their cytoplasm isn’t uniformly intensely pink in the same way as plasma cells.

So the best match for cells with intensely pink cytoplasmic staining is plasma cells.