The sunray or sunburst appearance on radiographs is a classic sign of osteogenic sarcoma (osteosarcoma), resulting from the tumor's aggressive periosteal reaction. The tumor causes new bone formation perpendicular to the cortex, producing radiating spicules resembling rays of the sun. This pattern indicates rapid and invasive bone growth typical of malignant osteoblastic activity. Other conditions like osteomyelitis or fibrous dysplasia do not typically produce this distinct periosteal reaction. Recognizing this radiographic feature is crucial for early diagnosis and appropriate surgical planning.

Reference: Orthopaedics: Principles and Their Applications, Rockwood & Green, 7th Edition.