A seventy-year-old lady had a hard tumor mass in left sacroiliac region. She was operated. Biopsy was taken from the left iliac crest and histopathological examination was done. Tumor measured 3×2×2 cms approximately. It was chalky-white ball-like. Its surface was lobulated. Microscopically, it showed small and large areas of necrosis and calcification. Areas of mild-to-moderate lymphocytic infiltration were seen. Fibrosis and hyalinization were seen. Bony trabeculae and osteoid formation were also seen. The patient was finally diagnosed as a case of primary tumoral calcinosis of sacroiliac region. Keywords: Soft tissue calcification necrosis osteoid formation chronic inflammation