hyperchromia

Hyperchromia is a term used in histology and cytology to describe an increase in staining intensity of cellular material compared with normal tissue. It is most often discussed in relation to nuclei, where the chromatin appears darker on hematoxylin–eosin stained sections. When applied to nuclei, the term is closely related to hyperchromasia, referring to nuclei with higher DNA content or more densely packed chromatin, which can enhance nuclear staining.

In pathology, hyperchromatic or hyperchromic features are frequently associated with malignant or dysplastic cells, although they are not specific for cancer. Increased chromatin density or DNA content can occur with rapid proliferation, aneuploidy, polyploidy, or severe cellular atypia. Hyperchromia can also be observed in tissues undergoing certain types of degeneration or in reactive processes, depending on the context and staining method.

Causes of a hyperchromic appearance include true cellular changes and technical artifacts. True hyperchromia may result from increased DNA or pigment deposition within cells, while artifacts such as dehydration, overstaining, or poor fixation can exaggerate staining intensity and mimic hyperchromia. Accurate interpretation relies on correlating staining patterns with cellular morphology, architectural context, and clinical information.

In summary, hyperchromia refers to unusually intense staining of cellular material, most commonly nuclei, and is an important, though not solely definitive, clue in assessing cellular atypia and potential malignancy. See also hyperchromasia for related concepts in nuclear morphology and hypochromia for contrast in staining intensity.