American Society for Clinical Pathology (ASCP) Histotechnologist Practice Test

Which of the following is a microscopic indicator of the presence of anthracotic pigment in tissues?

1. Dark granules in tissue

2. Red staining under polarized light

3. Orange granules throughout connective tissue

4. Clear spaces in the cytoplasm

The correct answer is: Dark granules in tissue

The presence of anthracotic pigment in tissues is primarily indicated by the identification of dark granules. Anthracotic pigment is the result of the accumulation of carbon particles, commonly from environmental pollution or smoking, that can be deposited within macrophages and connective tissue. Under microscopy, these pigments appear as dark, granular deposits, which stand out against the background of the tissue components. The other options do not relate to the characteristics of anthracotic pigment. For instance, red staining under polarized light is typically associated with substances such as certain types of crystals or fibers, and not carbon deposits. Orange granules in connective tissue might suggest the presence of other substances or pigments, such as hemosiderin, and clear spaces in the cytoplasm may indicate areas where lipids or other materials have been dissolved during processing, not anthracotic pigment. Thus, the identification of dark granules distinctly highlights the presence of anthracotic pigment in histological examinations.