Case ReportHeterotopic mesenteric and abdominal wall ossification - Two case reports in one institution

- Heterotopic ossification (HO) is related with the abnormal bone formation in tissues that normally do not ossify.
- Heterotopic mesenteric ossification is a rare form of HO, characterized by the formation of an ossificant pseudotumor in the mesenteric base.
- Pathophysiology of HO has been postulated to be due to osteoblastic metaplasia of multipotent mesenchymal cells in response to stimulus.
- Prognosis of HO is generally good, so treatment should be conservative, avoiding surgery to prevent further ossification.

IntroductionHeterotopic ossification occurs when bone develops in tissues which usually don't undergo ossification. Heterotopic mesenteric ossification, also known as intra-abdominal myositis ossificans, is a rare and benign form of ossification, usually related with previous abdominal surgery or trauma.Presentation of casesWe report two cases of heterotopic ossification both after multiple abdominal surgeries, with intraoperative findings of mesenteric and abdominal wall ossification. Histopathology revealed metaplastic bone deposition, without evidence of atypia or malignancy.DiscussionThis rare entity shares clinical and pathological characteristics of myositis ossificans. It is important to consider the differential diagnosis with sarcomas. In the cases described, the patients were proposed for elective surgery and this pathology was as an incidental finding.ConclusionThe simultaneous presence of mesenteric and abdominal wall ossification in both patients makes these cases even rarer.