Which histologic pattern most strongly supports reactive bone formation rather than tumor bone?

• A. Well-ordered maturation with organized thicker trabeculae attached to mature lamellar bone
• B. Intertrabecular spaces filled with pleomorphic cells
• C. Frequent atypical mitoses
• D. Absence of osteoblast lining

Answer: (A)

Reactive bone formation shows orderly remodeling, with mature lamellar bone and thickened trabeculae that are neatly organized and integrated with existing bone. This pattern reflects a controlled osteoblastic response and gradual maturation, consistent with a healing or reactive process rather than unchecked tumor growth. Therefore, a histologic finding described as well-ordered maturation with organized thicker trabeculae attached to mature lamellar bone best supports reactive bone formation. In contrast, intertrabecular spaces filled with pleomorphic cells or frequent atypical mitoses point to malignancy with cellular atypia and abnormal division, not a normal remodeling response. Absence of an osteoblast lining would be atypical for active reactive bone formation, where new surfaces are typically lined by osteoblasts during bone deposition.