Hematin is an artifact.

• A. True
• B. False
• C. Not sure
• D. Sometimes

Answer: (A)

Hematin is formed during tissue processing as a pigment artifact, not a normal tissue component. When blood-containing tissue is fixed, especially with formalin or in the presence of acids or oxidizing conditions, the heme in hemoglobin can be oxidized to ferric hematin. This ferric hematin appears as dark brown to black deposits, often along vessels or in areas of prior hemorrhage, and it reflects processing conditions rather than true tissue biology. Because it arises from the chemical changes of fixation rather than from the tissue’s inherent structure or disease process, it’s classified as an artifact.

To minimize hematin formation, use properly buffered fixatives, avoid overly acidic conditions or prolonged fixation, and ensure thorough washing during processing. If hematin is present, be aware it can confound interpretation by mimicking other pigments, so knowing it is artifact helps prevent misdiagnosis.