What color does osteoid appear in tumor bone histology?

• A. Glassy pale eosinophilic (fine strands)
• B. Basophilic (immature) matrix
• C. Dark blue mineralized matrix
• D. Clear translucent matrix

Answer: (A)

Osteoid is the unmineralized organic matrix produced by osteoblasts, so in standard H&E staining it appears pink (eosinophilic) and eosin-rich due to its collagen content. Because it has not yet been mineralized, the matrix looks glassy and pale rather than dark or blue. That pale, glassy eosinophilic appearance in fine strands best matches osteoid in tumor bone histology. In contrast, mineralized bone often shows different staining characteristics and the other descriptors don’t reflect the unmineralized, eosinophilic nature of osteoid.