Incidental giant mesenteric lipoma: A case report

Abstract

Lipomas are common benign fatty tumors, but their occurrence in the mesentery is exceedingly rare. While usually asymptomatic and underreported, they may grow to a considerable size and cause obstruction, volvulus, abdominal pain, or discomfort. We report the case of a 63-year-old Arab female who presented with a 10-day history of intermittent right upper quadrant abdominal pain radiating to the back, worsened by cold exposure and meals, along with months of mild constipation and progressive distension. Clinical examination showed mild, nontender abdominal distension, and imaging revealed a 2 cm gallstone, a gallbladder polyp or sludge, and a large intra-abdominal mass. Contrast-enhanced CT (Computed Tomography) confirmed a well-defined, encapsulated mesenteric lipoma measuring 28.5 × 17 × 6.5 cm. The patient underwent simultaneous cholecystectomy and mass excision, and histopathology confirmed chronic cholecystitis and a benign mesenteric lipoma. This case underscores the importance of considering mesenteric lipomas in the differential diagnosis of vague abdominal complaints and highlights the critical role of radiological assessment in guiding definitive surgical management.

Introduction

Lipomas are benign tumors composed of adipose tissue [1]. They are uncommon in the hands, feet, and face, but are typically found in the subcutaneous tissue of the trunk and proximal extremities. Rarely, they may occur in the intestines, breast, pancreas, and oral cavity; mesenteric lipomas are among the rarest types [[2], [3], [4], [5]]. Their exact prevalence remains uncertain, as many lipomas are asymptomatic and undetected [6]. While they are typically asymptomatic, lipomas can grow to considerable sizes and eventually produce symptoms of obstruction or volvulus, such as abdominal pain and discomfort [7]. We present the case of a 63-year-old female who was incidentally diagnosed with one of the largest colonic mesenteric lipomas reported to date.

Case presentation

A 63-year-old married Arab female presented with a 10-day history of intermittent right upper quadrant (RUQ) pain radiating to the back, worsened by cold exposure and food intake. She denied fever, nausea, vomiting, or jaundice. Her medical history was notable only for a cesarean section 30 years earlier and a 40-pack-year smoking history (she quit one year ago). There was no family history of gastrointestinal disease or tumors.

On admission, her vital signs were stable (blood pressure 120/80 mmHg, heart rate 98 bpm, SpO₂ 99%). Abdominal examination revealed mild distension without tenderness; Murphy’s sign and digital rectal exam were negative. She also reported mild constipation and progressive abdominal distension over several months.

Laboratory studies revealed a WBC count of 7.3 × 10⁹/L (normal: 4.0-11.0), hemoglobin 11.2 g/dL (slightly below the normal range of 12-16), hematocrit 36% (normal: 36-46), platelet count 237 × 10⁹/L (normal: 150-400), creatinine 0.9 mg/dL (normal: 0.6-1.2), and ALT 20 U/L (normal <40). These results showed no evidence of infection, anemia requiring intervention, or hepatic/renal dysfunction.

RUQ ultrasound demonstrated a 2 cm gallstone, a 21 mm echogenic shadow at the gallbladder neck (suggestive of a polyp or sludge), and a large mass extending from the splenic hilum toward the midline. Contrast-enhanced CT confirmed a 28.5 × 17 × 6.5 cm, well-defined, encapsulated, predominantly adipose mesenteric mass (Fig. 1). The differential diagnosis included liposarcoma, lymphangioma, lymphangiolipoma, and dermoid cyst, findings that necessitated surgical removal of both the mass and the gallbladder via open laparotomy. Given the giant size of the tumor, its uncertain relationship with adjacent abdominal organs, and the need for safe vascular control during dissection, an open approach was preferred over laparoscopy.

Fig. 1.

Axial CT scan showing a well-defined, encapsulated, homogeneous fat-density mass consistent with a giant mesenteric lipoma. The lesion measures approximately 28.5 × 17 × 6.5 cm and displaces adjacent abdominal structures without infiltration.

Under general anesthesia, a vertical midline incision was made above and below the umbilicus through the skin, subcutaneous tissue, and linea alba to enter the peritoneal cavity. Upon entry, no free fluid was observed, and bowel loops were retracted. A large yellow-tan mesenteric mass arising from the colon mesentery was identified. The overlying peritoneum was incised, and the vascular pedicle was isolated, double-ligated, and divided. Blunt-sharp dissection freed the mass while preserving adjacent colonic vessels. The 28.5 × 17 × 6.5 cm lipoma was excised en bloc and sent for histopathological examination (Fig. 2).

Fig. 2.

Gross specimen of the excised mesenteric lipoma, showing lobulated yellow adipose tissue with focal hemorrhagic areas. The mass measured 28.5 × 17 × 6.5 cm and was confirmed on histopathology to be a benign encapsulated lipoma.

Attention then turned to the gallbladder. The fundus was retracted cephalad to expose Calot’s triangle. The cystic duct and artery were skeletonized, doubly ligated, and divided. Retrograde dissection from the liver bed using electrocautery completed gallbladder removal. Hemostasis was secured, and the specimen was retrieved in a bag. The remainder of the procedure was uneventful.

Pathologic examination of the gallbladder confirmed chronic cholecystitis with a 2 cm gallstone and mucosal ulcers but no malignancy (Fig. 3). The mesenteric mass consisted of a large, encapsulated yellow adipose tumor with areas of hemorrhage (Fig. 4, Fig. 5). Histopathology confirmed a benign encapsulated mesenteric lipoma.

Fig. 3.

Histopathological section of the gallbladder (H&E stain), showing features suggestive of chronic cholecystitis, including mucosal changes and inflammatory cell infiltration.

Fig. 4.

Histopathological section of the excised mesenteric mass (low magnification, H&E stain), demonstrating a well-circumscribed encapsulated lesion with mature adipose tissue, which is consistent with a mesenteric lipoma.

Fig. 5.

Histopathology of mesenteric lipoma (hematoxylin & eosin stain, low power field). The section shows mature adipose tissue with thin fibrous septa, confirming the diagnosis of benign mesenteric lipoma.

Postoperatively, the patient experienced a mild allergic reaction and possible pulmonary edema following a blood transfusion but recovered well with supportive care. Her abdominal pain and distension resolved after surgery. Follow-up imaging showed no recurrence, and she made a full recovery. Given the benign nature of the lesion, no further oncologic treatment was required.

Discussion

Mesenteric lipomas are benign mesenchymal soft tissue tumors derived from adipocytes and are most frequently found in the trunk and proximal extremities. Their presence in distal extremities, the face, oral cavity, breast, pancreas, and intestines is unusual, with mesenteric lipomas being among the rarest [1,5]. Although their exact prevalence remains unclear, it is likely underreported, as many lipomas are asymptomatic and undetected [6].

Mesenteric lipomas are typically identified incidentally on abdominal imaging; however, when symptoms do occur, they vary according to the tumor’s size, location, and growth rate [6,8]. The differential diagnosis includes entities such as dermoid cysts, liposarcoma, lymphangioma, lipoblastoma, lymphangiolipoma, and neuroblastoma [2]. Imaging features significantly associated with ALTs/WDLs (atypical lipomatous tumors/well-differentiated liposarcomas) include tumor size ≥110 mm, septation >2 mm, nodularity, contrast enhancement, and irregular margins [9]. Accurate differentiation is crucial to prevent unnecessary invasive procedures such as preoperative biopsy [2,10].

Accurate preoperative diagnosis of mesenteric lipomas remains challenging due to their deep location and nonspecific presentation. Ultrasonography is often the first imaging modality, demonstrating a homogeneous or heterogeneous echogenic mass that can be mistaken for normal mesenteric fat [6]. Contrast-enhanced CT is preferred for definitive evaluation, characteristically depicting a well-circumscribed, homogeneous fat-density lesion with fine internal septations and no invasive features [11]. MRI helps with differentiation: lipomas show a consistent signal intensity similar to subcutaneous fat on both T1- and T2-weighted sequences, without the nodular or non-adipose components that are characteristic of liposarcoma [12].

While small, asymptomatic mesenteric lipomas are often managed conservatively, larger and symptomatic lesions generally require complete surgical excision, performed either via laparotomy or laparoscopy [13,14]. In cases where the tumor involves a segment of the bowel, resection with end-to-end anastomosis is typically indicated [,15]. Recurrence is rare and is usually associated with incomplete resection [11].

In our case, a 63-year-old female presented with a 10-day history of intermittent RUQ pain radiating to the back, along with mild constipation and progressive abdominal distension over several months. Although her initial clinical presentation suggested gallbladder pathology, radiological imaging revealed a large mass in the colonic mesentery, which was incidentally identified during evaluation for chronic cholecystitis. Our approach was guided by the ultrasound and CT results; however, MRI was not performed due to institutional limitations. Despite the large size, the lesion lacked thick or nodular septa or non-fatty components, favoring the diagnosis of lipoma. Surgical excision and histopathological examination confirmed a 28.5 × 17 × 6.5 cm encapsulated mesenteric lipoma with hemorrhagic areas and no evidence of malignancy. This case is particularly notable for the tumor’s exceptional size, its origin from the colonic mesentery, and its incidental discovery in a patient evaluated primarily for gallbladder disease. The coexistence of two distinct pathologies permitted simultaneous cholecystectomy and lipoma excision, and the decision to perform open laparotomy ensured safe vascular control during removal. These aspects highlight the importance of thorough radiological evaluation, the inclusion of mesenteric lipomas in the differential diagnosis of vague abdominal symptoms, and the value of tailoring surgical planning to both the tumor’s characteristics and the patient’s overall presentation.

Conclusion

This case represents one of the largest mesenteric lipomas reported in the literature. It underscores the importance of comprehensive radiological assessment in patients with vague abdominal symptoms and highlights the need to consider mesenteric lipomas in the differential diagnosis.

Ethics statement

Ethics approval was not required for this study.

Data availability

The manuscript contained all data related to this case report.

Patient consent

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal upon request.