Nonsurgical treatment of postoperative intestinal obstruction caused by heterotopic ossification of the mesentery: A case report

Abstract

BACKGROUND

Among all forms of heterotopic ossification, heterotopic mesenteric ossification (HMO) is rare, with fewer than 100 reported cases to date. Postoperative early small bowel obstruction caused by HMO is even rarer, presenting extremely high surgical risks, the potential for multiple surgeries, and a poor prognosis. There have been no reported cases of conservative treatment for resolving such early postoperative obstruction.

CASE SUMMARY

A 57-year-old male presented with severe postoperative small bowel obstruction shortly after undergoing open radical resection for transverse colon cancer. Laparotomy revealed extensive adhesions in the proximal jejunum and mesentery, making it too difficult to relieve without injuring the small bowel. Additionally, multiple fixed nodules were found in the mesentery during the operation. Pathology confirmed the presence of heterotopic ossification. The patient was treated with methylprednisolone on postoperative day 1, which gradually relieved his symptoms.

CONCLUSION

Hormone therapy may have a potential role in treating small bowel obstruction caused by early HMO after operative intervention.

Key Words: Heterotopic mesenteric ossification; Hormone therapy; Bowel obstruction; Methylprednisolone; Surgery; Case report

Core Tip: In this case, we present a unique treatment approach for resolving early postoperative heterotopic ossification of mesentery-induced small bowel obstruction. There was difficulty dissecting the small bowel obstruction during the second surgery, thus we tried treatment with methylprednisolone, which gradually relieved the patient’s bowel obstruction, thereby providing a new and effective strategy for early postoperative heterotopic ossification of the mesentery-induced small bowel obstruction and hypothesizing that early postoperative heterotopic ossification of the mesentery is a specific postoperative inflammatory response.

INTRODUCTION

Heterotopic ossification refers to the formation of bone tissue in soft tissue where there is normally no bone tissue, which is an unusual pathological state. Heterotopic ossification was first discovered by the German doctor Riedel in 1883 and is commonly found in the limbs, especially the elbow joint[1]. Heterotopic mesenteric ossification (HMO) is extremely rare. In 1983, Hansen et al[2] first reported HMO. However, to date, fewer than 100 cases have been reported. Here, we report the case of a patient with colorectal cancer who underwent radical resection and developed HMO within a short period of time, accompanied by severe intraabdominal obstruction. Despite our inability to resolve the obstruction during surgery, treatment with methylprednisolone gradually relieved the patient’s obstruction and prevented further progression of HMO.

CASE PRESENTATION

Chief complaints

A 57-year-old Han Chinese male underwent open radical surgery for transverse colon cancer. Postoperative abdominal distension progressively worsened, and severe abdominal pain developed on the 14^th day after surgery, which was unbearable.

History of present illness

The patient underwent open radical resection for transverse colon cancer. On the fifth day after surgery, the patient experienced persistent abdominal distension and was unable to pass gas or stool. We employed non-operative managements, including nasogastric decompression, fluid resuscitation, and correction of electrolyte abnormalities. On the 13^th postoperative day, the patient’s abdominal distension intensified. We suspected that intestinal obstruction might be due to stenosis at the anastomotic site. Colonoscopy revealed that the anastomotic site was unobstructed. Consequently, we further identified intestinal obstruction in multiple segments of the small intestine through computed tomography (CT). On the 14^th day, the patient’s abdominal distension worsened, and the patient experienced unbearable abdominal pain. Intestinal obstruction after radical resection of transverse colon cancer was considered.

History of past illness

The patient had a 15-year history of hypertension, which was controlled. He was diagnosed with cerebral hemorrhage in 2011 and underwent left inguinal hernia repair 8 years ago.

Personal and family history

The patient denied any family history of malignant tumors.

Physical examination

Physical examination revealed abdominal distention, abnormal bowel sounds, tenderness in the abdomen, and no Blumberg’s sign.

Laboratory examinations

Alkaline phosphatase activity was elevated, and other indicators were normal.

Imaging examinations

Colonoscopy revealed that the anastomosis was unobstructed without stenosis, but the mucosa of the proximal small intestine was markedly edematous, making it impossible for the colonoscope to pass through. A CT scan revealed dilation of the small bowel (Figure 1A and B), but no other abnormalities were observed.

Figure 1 Abdominal computed tomography revealed intestinal obstruction of the patient after abdominal surgery. A: The yellow arrow indicated the patient's intestinal obstruction at the right renal hilus level; B: The blue arrow indicated the patient’s intestinal obstruction at the umbilical level.

FINAL DIAGNOSIS

The final diagnosis was intestinal obstruction.

TREATMENT

Laparotomy revealed segmental intestinal obstruction in multiple segments, with extensive and tight adhesions of the proximal jejunum and mesentery near the flexure of the ligament of Treitz, approximately 35 cm from the ligament. The original colonic flexure and the original site of the hepatic flexure were also extensively adhered (Figure 2A). The entire small intestine was adhered together like a cake, and the adhesion strength was significantly greater than that of normal abdominal adhesions 14 days after surgery. There was no free small intestine longer than 10 cm in the abdominal cavity, which prevented us from identifying the proximal and distal ends. Thus, enterostomy could not be performed. Attempts at blunt and sharp dissection failed to completely resolve the intestinal obstruction. Even if the surgeon avoided the use of energy-based cutting, carefully dissecting the patient with scissors can still easily damage the small intestine. Additionally, multiple fixed nodules, which were not present in the previous operation, were found in the mesentery during the operation (Figure 2B). If these fibroses and adhesions were forcibly dissected, there would be a high risk of small intestinal fistula development, so the abdomen was closed. After pathological analysis of mesenteric nodules, patchy new cartilage, bone tissue, and fibrous tissue were found to have proliferated (Figure 3A and B).

Figure 2 Intraoperative observations may reveal the presence of abdominal adhesions and mesenteric nodules. A: The yellow arrow indicated a tight adhesion between the mesentery and the small intestine; B: Blue arrow indicated multiple hard nodules in the mesentery.

Figure 3 Pathological findings of surgical specimens. A and B: Representative hematoxylin and eosin images of mesenteric nodules. Hematoxylin and eosin images showed heterotopic ossification and new bone formation. Black color scale bars: 200μm. The immunohistochemical staining results were as follows: CD68 (+), smooth muscle actin (+), CD34 (+), β-catenin (cytoplasmic+), Ki-67 (+20%), and deamin (-).

Postoperative care included fasting, placement of an intestinal obstruction set, suppression of digestive fluid secretion with octreotide, and nutritional support. The intestinal obstruction set was difficult to place through the ligament of Treitz. Methylprednisolone was given for anti-inflammatory and symptomatic treatment for one week, with an initial dose of 40 mg per day followed by 40 mg twice a day for the next two days and then 40 mg per day until the seventh day, followed by discontinuation on the eighth day. The patient was monitored closely for complications such as stress ulcers and electrolyte imbalances.

OUTCOME AND FOLLOW-UP

The intestinal obstruction gradually improved after one week of hormone therapy (Figure 4A), and the patient was discharged from the hospital on the 25^th day after the second surgery. At the eight-month follow-up visit, the patient reported no discomfort. CT imaging revealed no significant abnormalities (Figure 4B).

Figure 4 Abdominal computed tomography showed a significant alleviation of intestinal obstruction following methylprednisolone treatment. A: After 1 week of methylprednisolone treatment, there was a marked reduction in the intestinal obstruction; B: 8 months after methylprednisolone treatment.

DISCUSSION

The occurrence of HMO is the result of specific signaling molecules in the peritoneal cavity that induce mesenchymal stem cell osteogenesis, and abdominal trauma and surgery seem to be the triggering factors for this process[3,4]. Another explanation is that trauma and surgery lead to the transplantation of bone tissue to the mesentery[5]. A review of the literature (Supplementary Table 1) revealed that most of the reported cases of HMO were found in males (57/64, 89.06%), with a median age of 51.5 years (range 21-88 years), and are closely related to a history of abdominal trauma and surgery (52/58, 89.66%). The remaining cases were spontaneous HMO[6]. HMO primarily occurs in the small intestinal mesentery (50/64, 78.13%), and the symptoms mainly manifest as small intestinal obstruction (32/58, 55.17%)[7] and enterocutaneous fistula (6/58, 10.34%)[8]. There are no specific laboratory findings associated with HMO, and only alkaline phosphatase may be elevated[9], which may be related to the increased activity of osteoblasts and the need for more case support. The unique feature of this case was the rapid formation of bone tissue, with bone formation occurring within 14 days, which may have been due to insufficient deposition of calcium salts, and the CT scan did not show a high-density image. Second, HMO is accompanied by a strong inflammatory reaction in the abdominal cavity, with extensive adhesions forming between the small intestine, mesentery, and peritoneum. Finally, after hormonal therapy, there was gradual relief of the intestinal obstruction that could not be relieved by mechanical dissection, which is encouraging. The patient’s stool gradually transformed from a clay-colored consistency to a normal appearance (Supplementary Figure 1). Most gastrointestinal surgeons might not encounter such postoperative complications during their career. However, they should remain vigilant in preventing inflammatory intestinal obstruction caused by early postoperative HMO. Although only 7 cases of early postoperative HMO have been reported, they share common features: Rapid onset, extensive adhesions leading to difficulty in dissection, small intestinal obstructions, thick mesenteries, and hard fibrous osteoid tissue forming on the mesentery within 1 month after surgery. In such instances, there is a significantly elevated surgical risk owing to the inability to dissect inflammatory adhesions without causing damage to the small intestine. This increases the likelihood of multiple operations, reduces patient tolerance for such procedures, and leads to a poor prognosis. Only one of the seven patients recovered after intestinal adhesion dissection (Table 1)[10], and one patient recovered after the removal of 240 cm of the obstructed small intestine in addition to receiving nonsteroidal anti-inflammatory drug treatment[11]. Two patients died from postoperative complications resulting from multiple surgeries[12,13]. Moreover, three patients experienced recurrence following adhesiolysis or intestinal resection, necessitating multiple subsequent surgeries[2,14,15].

Table 1 Summary of the previously reported cases of early postoperative heterotopic omental ossification.

Year	Age	Sex	Primary disease/operation	Clinical history	Onset	Site	Therapy	Outcome
1983	55	Male	Ulcerative colitis/surgery	SBO	2 weeks	M	OP	Relapse
2000	25	Male	Fire-gun injury/surgery	SBO	2 weeks	M	OP	Relapse
2005	74	Male	Intestinal obstruction/surgery	SBO	10 days	M, O	OP	Death
2010	50	Male	Morbid obesity/surgery	Fistula/SBO	12 days	M, O	OP	Relapse
2011	39	Male	Cancer/surgery	SBO	2 weeks	O	OP	Recovery
2014	88	Male	Abdominal aortic aneurysm/surgery	SBO	2 weeks	M	OP + NSAIDs	Recovery
2018	72	Male	Cancer/surgery	SBO	SW	M	OP	Death

SBO: Small bowel obstruction; SW: Several weeks; M: Mesentery; O: Omentum; OP: Operation; NSAIDs: Nonsteroidal anti-inflammatory drugs.

Ectopic ossification may represent a nonspecific inflammatory response. Methylprednisolone has been shown to inhibit inflammation resulting from both infectious and noninfectious factors by preventing inflammatory mediators from reacting and inhibiting complement involvement in the inflammatory response while also mitigating tissue damage repair following inflammation. In the advanced stage of inflammation, it can also suppress the vitality of fibroblasts, decrease the soluble collagen components in tissues, and minimize adhesion and scar formation. Although there are no documented successful cases thus far, hormonal therapy has emerged as an option that should potentially be pursued. Without such intervention, patients may face imminent mortality due to the inability to sustain parenteral nutrition or progressive energy failure. Fortunately, we successfully treated these inflammatory bowel obstructions with methylprednisolone, avoiding the risk of multiple surgeries, preserving the patient’s entire small intestine, and saving the patient’s life. The patient has been discharged from the hospital for more than eight months, and follow-up examinations revealed that the patient is in excellent health. Surgeons should consider this approach as a final attempt when confronted with similar challenges subsequent to unsuccessful surgical intervention (Video 1).

CONCLUSION

In conclusion, early HMO may be accompanied by severe intra-abdominal inflammatory reactions, leading to intestinal obstruction. Our therapeutic approach provides a new treatment possibility for intestinal obstruction caused by early postoperative HMO, but more clinical cases are still needed for confirmation.

ACKNOWLEDGEMENTS

We appreciate the cooperation of the patient and his family during the treatment.