When ectopic bone forms in the abdomen: The diagnostic and management challenges of heterotopic mesenteric ossification

Abstract

Heterotopic mesenteric ossification (HMO) is a rare medical condition, with < 100 cases reported globally by 2024. This disorder is characterized by abnormal bone tissue formation within the mesentery, often following abdominal trauma, ischemia, or infection. This editorial reviews the case presented by Zhang et al, involving a 34-year-old male who developed persistent left lower abdominal pain after sustaining blunt trauma to the abdomen. Diagnostic challenges arose due to the rarity and nonspecific presentation of HMO, which shares histopathological features with conditions such as myositis ossificans and necessitates differentiation from malignancies like sarcomas. Advanced imaging revealed calcifications suggestive of HMO, but definitive diagnosis was achieved only through surgical resection and histopathological analysis, which confirmed the presence of ectopic bone formation. Although benign, HMO can result in severe complications, such as bowel perforation or obstruction. Therefore, awareness of HMO is crucial for clinicians to ensure timely and appropriate treatment.

Key Words: Abdominal trauma; Heterotopic mesenteric ossification; Abdominal surgery; Ectopic bone formation; Diagnostic challenges; Clinical vigilance

Core Tip: This editorial comments on the case report by Zhang et al, detailing the rare occurrence of heterotopic mesenteric ossification (HMO), often associated with abdominal trauma or surgery. The study highlights the diagnostic challenges due to nonspecific symptoms and emphasizes the importance of considering HMO in differential diagnoses when imaging reveals calcifications in patients with history of abdominal trauma. While surgical resection remains the primary treatment, recurrence and complications necessitate further research to better understand HMO’s pathogenesis and establish standardized treatment guidelines. This study reinforces the need for heightened clinical vigilance and multidisciplinary approaches in managing such rare and complex cases.

INTRODUCTION

Zhang et al[1] provided an interesting case report. Heterotopic mesenteric ossification (HMO) is a condition where bone formation occurs within the mesentery, a fold of membrane attaching the intestine to the abdominal wall and holding it in place. HMO is an extremely rare condition, with < 100 cases reported globally, posing significant diagnostic and therapeutic challenges. HMO predominantly affects males in mid to late adulthood, often presenting with bowel obstruction[2,3]. The case by Zhang et al[1], reporting a 34-year-old male without previous medical or surgical history who developed HMO following blunt trauma to the left lower abdomen, emphasizes the need for increased clinical awareness and the development of more robust diagnostic protocols.

HMO often remains unfamiliar to many clinicians. While < 40 cases were reported by 2015, this number increased to 100 by 2024, indicating growing awareness[3,4]. Due to its rarity and nonspecific symptoms, HMO can easily mimic more common conditions such as intestinal obstruction, tumor, or inflammatory diseases[2]. In this case report, the patient’s persistent abdominal pain and palpable mass could have been misdiagnosed as another gastrointestinal disorder. While the authors successfully established the correct diagnosis, this case highlights the necessity for maintaining a higher index of suspicion, particularly in patients with a history of abdominal trauma or surgery.

DISCUSSION

The exact pathogenesis of HMO remains incompletely understood. Blunt force trauma is hypothesized to cause tissue damage within the mesentery, triggering a cascade of inflammatory and reparative reactions. This damage, combined with altered vascularity or ischemia, leads to the differentiation of mesenchymal stem cells into osteoblasts within the mesentery[5]. Hence, computed tomography (CT) can reveal hyperdense ossification in the mesentery[6]. Similarly, Zhang et al[1] reported evidence of pericolonic infiltration and calcification in the wall of the left lower colon when an abdominal CT was performed. Histologically, HMO exhibits reactive myofibroblastic proliferation with bone and osteoid production, distinguishing it from extraskeletal osteosarcoma[7]. Although benign, HMO can cause severe complications, including fatal bowel obstruction[2]. The time range for HMO presentation following abdominal trauma or surgery may be extended, necessitating ongoing consideration during differential diagnosis[2]. Therefore, further research is needed to elucidate the pathogenesis of HMO and develop optimal management strategies[3].

There is currently no established unified treatment regimen for HMO; thus, the therapeutic approach remains contentious. Treatment primarily includes conservative management and surgery, each with its own set of indications, benefits, and limitations. Of these, surgical resection becomes the most effective treatment method in cases of HMO-related severe complications, such as intestinal obstruction, fistulas, or perforation[2,8]. In the case report by Zhang et al[1], the patient underwent laparoscopic radical sigmoid colon resection, a necessary intervention to alleviate symptoms associated with the observed sigmoidal stenosis and prevent further complications. While surgery effectively addresses the immediate issues, it carries inherent risks, including the potential for ossification recurrence. Hence, postoperative management may require the use of non-steroidal anti-inflammatory drugs and cimetidine to prevent recurrence[9]. Therefore, the decision to proceed with surgery must be carefully weighed against the potential benefits and risks, considering the severity of the patient’s condition and the likelihood of recurrence.

Conservative management is often preferred in cases where the symptoms are mild, when the risk of complications is low aiming to prevent further ossification[10,11]. Medications such as anti-inflammatory agents, analgesics, calcium, and vitamin D are prescribed for management of pain, inflammation and to maintain balanced bone metabolism, respectively[1,12]. Conservative treatment is typically employed to control symptoms rather than to eliminating heterotopic ossification. The absence of a standardized treatment protocol for HMO is a significant challenge in its management. Hence, further clinical research is urgently needed to develop consensus guidelines that can inform the decision-making regarding both conservative and surgical approaches.

Furthermore, diagnosing HMO is complex, primarily due to the nonspecific nature of its symptoms and the overlap with other conditions. The histopathological features of HMO share similarities with myositis ossificans, which can complicate the diagnostic process[7]. Both conditions are characterized by a central area of spindle-shaped fibroblasts transitioning to bone-like tissue peripherally, with mature bone trabeculae lined by osteoblasts. However, key differentiating factors include the absence of malignant transformation in HMO and the lack of pathological mitoses or cytological features of neoplastic cells, which are characteristic of cancerous ossifications. Despite its crucial role, imaging, including CT, often fails to definitively distinguish HMO from other pathology. In Zhang et al’s case, CT imaging revealed thickening of the colon wall and pericolonic fat stranding with calcifications, findings suggestive of HMO[1]. However, the definitive diagnosis was only made intra and postoperatively through observed sigmoid colon stenosis and histopathological examination of the resected intestinal segment revealing spindle-shaped or intertwining cell arrangements with focal areas of new bone formation. Consequently, while being indispensable, imaging is often insufficient on its own; thus, histopathology is essential for the comprehensive diagnosis of HMO.

CONCLUSION

In conclusion, HMO, although rare, presents a notable clinical challenge due to nonspecific symptoms, diagnostic complexity, and the absence of standardized treatment protocols. This study highlights the critical need for heightened clinical awareness and meticulous differential diagnosis, particularly in male patients with a history of abdominal trauma or surgery presenting with mesenteric calcifications. While advanced imaging and histopathological examination remain essential for accurate diagnosis, the development of more specific diagnostic tools is imperative. Thus, future research, particularly case series and retrospective studies, is vital to address the existing gaps in understanding the pathogenesis, progression, and optimal management of HMO. Expanding the evidence base could pave the way for targeted diagnostic and therapeutic strategies, ultimately enhancing patient care and guiding clinicians in decision-making for this rare yet significant disorder.