Heterotopic Mesenteric Ossification With Trilineage Hematopoiesis

Abstract

Heterotopic ossification (HO) histologically refers to extraskeletal bone formation in non-ossifying tissues, most commonly noted in the extremities, buttocks, abdominal wall, and hip joints. HO developing in the mesentery (heterotopic mesenteric ossification, HMO) is very rare, with fewer than 100 cases reported in the literature. It usually occurs in adult male patients with a history of repeated abdominal trauma. So far, only two cases of HMO have been reported with the development of hematopoietic bone marrow. Here, we report the third case of HMO with true trilineage hematopoiesis in a 66-year-old female with suspicious mesenteric-retained foreign material from prior surgical procedures, including hysterectomy for endometrial adenocarcinoma and multiple repairs for incisional hernia.

Keywords: ectopic bone formation; extramedullary hematopoiesis; heterotopic ossification; mesenteric ossification; metaplastic ossification; myositis ossificans.

Figure 1. Photomicrographs for HMO with true trilineage hematopoiesis.

A: The 1.5-cm well-circumscribed firm mass in the mesentery was confirmed to be an HMO with bone trabeculae and well-developed bone marrow at low-power magnification. B: The high-power field demonstrates that the trabeculae are composed of mature cortical lamellar bone with focally rimming osteoblasts, mature osteocytes in lacunae and cement line, and true trilineage hematopoiesis with erythropoiesis, granulocytopoiesis, and megakaryocytopoiesis among adipocytes. HMO: heterotopic mesenteric ossification