mucicarmine

Mucicarmine is a histological stain used to detect mucins in tissue sections. It is a carmine-based dye that selectively binds to acidic mucopolysaccharides, staining mucin-containing cells and extracellular mucin a characteristic red to pink color. A counterstain, typically hematoxylin, provides blue nuclei and general tissue contrast. The stain is especially valuable for identifying goblet cells and mucin production in various epithelia.

In practice, mucicarmine is widely used in surgical pathology to aid the diagnosis of mucin-producing lesions. It helps distinguish mucinous or signet-ring cell carcinomas from non-mucinous tumors in organs such as the colon, stomach, pancreas, biliary tract, and respiratory tract. Because it highlights mucin, it is often employed alongside other mucin stains (for example Alcian blue and Periodic acid–Schiff) to characterize the type of mucin present and to differentiate neutral from acidic mucins or sulfomucins.

Interpretation relies on the red staining of mucin, with the surrounding tissue and nuclei counterstained to provide context. Limitations include variability with fixation and processing, and the possibility of false negatives in samples with very little mucin or compromised staining. Therefore, mucicarmine is frequently used as part of a panel of stains rather than as a stand-alone test.

See also: Alcian blue–PAS staining for mucin differentiation; histochemical staining techniques; goblet cell biology.