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Year : 2022  |  Volume : 28  |  Issue : 2  |  Page : 194-197

Heterotopic mesenteric ossification

1 Department of General Surgery, Government Medical College, Kozhikode, Kerala, India
2 Department of Surgical Gastroenterology, Government Medical College, Kozhikode, Kerala, India

Date of Submission24-Nov-2022
Date of Decision01-Dec-2022
Date of Acceptance02-Dec-2022
Date of Web Publication30-Jan-2023

Correspondence Address:
Dr. Roshan Rajan
Department of General Surgery, Government Medical College, Kozhikode, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ksj.ksj_46_22

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Heterotopic calcification has been previously noted in healed laparotomy scars, within the peritoneum and is extremely rare. Heterotopic mesenteric ossification (HMO) is a rare disease that refers to intra-abdominal calcification of unknown aetiology, involving the mesentery. They can lead to serious complications such as enterocutaneous fistulations, intestinal obstruction, perforation and recurrent sepsis. We report a case of 26-year-old who presented with recurrent intra-abdominal collection, following an operation for blunt trauma abdomen, and was found to have HMO. He underwent exploratory laparotomy, and multiple intrabdominal new bone formations were observed, especially over the small bowel mesentery.

Keywords: Intra-abdominal calcification, heterotopic mesenteric ossification, intra-abdominal collection

How to cite this article:
Rajan R, Prathapan V K. Heterotopic mesenteric ossification. Kerala Surg J 2022;28:194-7

How to cite this URL:
Rajan R, Prathapan V K. Heterotopic mesenteric ossification. Kerala Surg J [serial online] 2022 [cited 2023 Mar 24];28:194-7. Available from: http://www.keralasurgj.com/text.asp?2022/28/2/194/368603

  Introduction Top

Ectopic calcifications can be histologically classified as dystrophic calcification and heterotopic calcification. Dystrophic calcification refers to the deposition of amorphous calcium without osteoblasts, while calcification with histologic characteristics of normal bone is heterotopic ossification. Heterotopic bone formation refers to new bone formation in a tissue that normally does not ossify. They have osteoblasts and lamellar bone identical to native bone. Heterotopic ossification has long been associated with several conditions such as neurological injuries/total hip arthroplasty, primarily involving hips and knees.[1] They are reported only rarely within the abdominal cavity, specifically in a mesenteric location. Heterotopic mesenteric ossification (HMO) is a rare disease that results in intra-abdominal ossification of unknown origin. Previous operations and trauma are causative factors.[2]. HMO even though a benign condition, can often cause complications such as intestinal obstruction, enterocutaneous fistulations, perforation, sepsis or even death. Here is a case report on HMO, a 26-year-old, who had undergone multiple laparotomies following a blunt trauma abdomen and presented with an intrabdominal collection. He underwent exploratory laparotomy, and multiple intra-abdominal new bone formations were observed, especially over the small bowel mesentery.

  Case Report Top

A 26-year-old male was admitted to a medical college hospital, in Kozhikode, with complaints of diffuse abdominal pain and vomiting. On evaluation with ultrasound and contrast-enhanced computed tomography (CT) abdomen, an ill-defined fluid collection was noted at the right hypochondrium in the extraperitoneal location extending to the peritoneal cavity measuring approximately 3 cm × 3.6 cm extending inferiorly up to the ileostomy site and a collection of 2.6 cm × 5 cm × 3.5 cm noted in the anterior abdominal wall in infraumbilical location was noted, and a diagnosis of abdominal wall abscess was made. He was managed conservatively on antibiotics and analgesics due to his previous laparotomies.

Eight months before the current admission, following an accident, he sustained blunt trauma to the abdomen; the evaluation revealed a haemorrhagic contusion of the head of the pancreas and mesocolon injury with ascending colon devascularisation. For this, he underwent Explorative laparotomy + right hemicolectomy with stapled anastomosis and VAC-assisted closure dressing was done. He was kept intubated at intensive care unit, and the initial surgery was followed by multiple re-look surgeries. A decompressive loop ileostomy was done in one re-look surgery to aid abdominal closure. The abdominal wall closure was done after 2 weeks of injury, closing only skin and subcutaneous tissue. The patient was discharged home.

The patient returned to ER the following week, complaining of abdominal pain and distension. Imaging revealed fluid collection in the abdominal wall. Drainage did by interventional radiology team, draining 250ml of pus. The patient was later discharged on oral antibiotics/analgesics. Following this, he presented to mean corpuscular haemoglobin casualty in the present admission. Given previous surgeries, he was planned for CT abdomen pelvis with a fistulogram, which revealed subcutaneous collection with suspicious intra-abdominal communication with no obvious enterocutaneous fistula. He underwent exploratory laparotomy, wound exploration, abscess drainage and ileostomy closure planned. The operation disclosed extensive calcification of the abdominal wall at the site of the previous surgical incision [Figure 1] and dense adhesions throughout the abdomen. As the small bowel was dissected free, multiple small calcifications were uncovered over the mesentery [Figure 2]. Further dissection disclosed multiple irregular calcific structures with branched cylindrical shapes ranging in size from 2.3 cm × 3.0 to 6 cm × 2 cm. Histopathological examination of decalcified sections showed mature lamellar bone with fatty marrow and focal osteoblastic activity [Figure 3]; the patient was discharged free of symptoms after an uneventful recovery.
Figure 1: Showing calcification present at the site of the previous surgical incision

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Figure 2: Multiple calcifications of various sizes that were present over the small bowel mesentery

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Figure 3: Histopathological examination showing mature lamellar bone with fatty marrow and focal osteoblastic activity

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  Discussion Top

HMO is a rare type of heterotopic bone formation where the mesentery is studded with ectopic bone. HMO is a non-neoplastic reactive process involving the gastrointestinal tract and mesentery, which can cause diagnostic confusion with more aggressive neoplasms.[3],[2] The pathogenesis involves local differentiation of immature pluripotent mesenchymal cells or occasionally by traumatic or surgical implantation of bone or periosteum into the soft tissues.[4] The contributing factors include venous stasis, oedema, local trauma, inflammation and local osteoinductive factors.[1]

On review of the literature, to date, only about 33 cases have been reported.[5] Patients were middle to elderly men, most of them with a history of abdominal surgery.[2] They can have varied presentations, summarised in [Figure 4]. Intra-abdominal ossification occurs mainly in the mesentery (28 cases, 84.8%). In some reported cases occurring in the omentum (7 cases, 21.2%).[5]
Figure 4: Various presentations of heterotopic mesenteric ossification[5]

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Even though no laboratory abnormalities suggested osteogenic activity in this case. It has been reported, patients can have a transient decrease in serum calcium levels, and an increase in creatine kinase, and alkaline phosphatase levels.[1] Some patients were noticed to have high carbohydrase antigen-125 levels and elevated parathyroid hormone.[5]

Along with the high end of suspicion and above blood parameters, the radiological examination can help in diagnosis.[1] In this patient, an abdominal X-ray (AXR) revealed abnormal opacity at the laparotomy scar [Figure 5]. The imaging modalities such as fluorodeoxyglucose positron emission tomography-CT and Tc-99m bone single-photon emission CT can be considered in identifying intra-abdominal ossifications, but these are not routine for these patients.[5] A Three-phase radionuclide bone scan is helpful in early diagnosis. Apart from diagnosis, they are useful in differentiating mature from immature, as the latter recur after excision.[1] These modalities can be useful in a setting of high alkaline phosphatase levels reflecting the activity of osteoblasts and heterotopic bone formation, with suspicious ossification in AXR.[5] They may be misinterpreted as malignancy. Among the 33 cases, intra-abdominal ossifications were detected using a CT scan in 10 cases.[5],[6]
Figure 5: Abdominal Xray showing calcification along the midline laparotomy scar

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In the present case, after multiple discussions of CT [Figure 6], a high end of suspicion towards intra-abdominal ossification was made.
Figure 6: Contrast CT scan showing calcification at laparotomy scar and multiple intrabdominal mesenteric ossification

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Treatment aims to reduce the quantity of ectopic bone and to delay mineralisation. Even though surgery is curative, it invariably recurs and is a therapeutic challenge. According to prior studies, Non-steroidal anti-inflammatory drugs, cimetidine and free radical scavengers are recommended for the prevention of HMO in symptomatic patients.[5] Anti-inflammatory drugs have been shown to reduce the incidence and severity of heterotopic bone formation.[1] Cimetidine helps in cases of hyperparathyroidism to normalise serum PTH and calcium levels. Free radical scavengers, like allopurinol and N-acetyl cysteine, may also be used.[5]

This case report aims to draw a conclusive therapeutic strategy for HMO, as there has not been enough sufficient collective data regarding HMO and its treatment.[5]

  Conclusion Top

In summary, I reported a rare case of HMO that developed after an operation for blunt trauma abdomen, who presented with intra-abdominal abscess. The report touched on when to suspect a patient is having HMO, and specific investigations for a suspected HMO. It seems difficult to put forwards a therapeutic strategy for HMO based on this report. However, given its association in patients who have undergone previous surgery, the rarity of such occurrence, and the lack of collective data on HMO, the literature review in this paper will help to provide useful information about clinical features and optimal therapy for this rare disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Myers MA, Minton JP. Heterotopic ossification within the small-bowel mesentery. Arch Surg 1989;124:982-3.  Back to cited text no. 1
Bovo G, Romano F, Perego E, Franciosi C, Buffa R, Uggeri F. Heterotopic mesenteric ossification (”intraabdominal myositis ossificans''): A case report. Int J Surg Pathol 2004;12:407-9.  Back to cited text no. 2
Yantiss RK, Nielsen GP, Lauwers GY, Rosenberg AE. Reactive nodular fibrous pseudotumor of the gastrointestinal tract and mesentery: A clinicopathologic study of five cases. Am J Surg Pathol 2003;27:532-40.  Back to cited text no. 3
Patel RM, Weiss SW, Folpe AL. Heterotopic mesenteric ossification: A distinctive pseudosarcoma commonly associated with intestinal obstruction. Am J Surg Pathol 2006;30:119-22.  Back to cited text no. 4
Honjo H, Kumagai Y, Ishiguro T, Imaizumi H, Ono T, Suzuki O, et al. Heterotopic mesenteric ossification after a ruptured abdominal aortic aneurism: Case report with a review of literatures. Int Surg 2014;99:479-84.  Back to cited text no. 5
Hansen O, Sim F, Marton PF, Grüner OP. Heterotopic ossification of the intestinal mesentery. Report of a case following intraabdominal surgery. Pathol Res Pract 1983;176:125-30.  Back to cited text no. 6


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


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