Normal Positron Emission Tomography-Computerized Tomogram in a Patient with Apparent Mesenteric Panniculitis: Biopsy Is Still the Answer

A Clinical Review of Mesenteric Panniculitis

Mesenteric panniculitis (MP) is a benign condition characterized by chronic inflammation and fibrosis of adipose tissue mainly of the small bowel mesentery. MP is commonly detected incidentally on cross-sectional imaging of the abdomen and can be asymptomatic in up to nearly half of patients. The most frequent clinical symptom reported is abdominal pain, followed by bloating/distention, diarrhea, constipation, vomiting, anorexia, weight loss, fever, malaise, and nausea. On computed tomography, MP is seen as a mass-like area of increased fat attenuation within the small bowel mesentery, usually located in the left upper quadrant of the abdomen. This mass-like area envelops mesenteric vessels and displaces adjacent bowel segments. Lymph nodes are frequently seen within the area of mesenteric abnormality. One of the most common differential diagnoses of MP is lymphoma, and positron emission tomography/computed tomography may be performed if there is suspicion of a concurrent underlying malignancy. Because of the benign nature of MP, treatment decisions should be guided by severity of symptoms and presence of complications. First-line medical treatment is prednisone and tamoxifen. Surgery is reserved for cases of recurrent bowel obstruction. This article provides a review of MP, including its epidemiology, pathophysiology, clinical presentation, imaging findings, and treatment.

Mesenteric Panniculitis, Sclerosing Mesenteritis and Mesenteric Lipodystrophy: Descriptive Review of a Rare Condition

Mesenteric panniculitis (MP) is the preferred nomenclature for a continuum of inflammatory diseases of the mesentery. The diagnosis of MP is often based on the appearance of a mass-like structure at the root of the mesentery. Characteristic histology includes focal fat necrosis, chronic inflammation, and sometimes mesenteric fibrosis. At present, robust literature related to diagnosis and management of MP are limited. MP is postulated to be an immune-mediated chronic inflammatory and/or a paraneoplastic disease. A personal or family history of other autoimmune diseases is commonly apparent. Several inciting events have been identified that possibly act as triggers in the development of the disease. Trauma, abdominal surgery, infection, and various cancers have been associated with mesenteric panniculitis. There are several diagnostic and histologic criteria that aid in making the diagnosis of MP. The differential diagnosis for a mesenteric mass includes neoplastic disease, and a biopsy may be indicated to rule out other conditions. While cases of MP with a short duration of symptoms, or spontaneously regression may occur, some patients experience prolonged periods of pain, fever, and alterations in bowel habit, causing significant morbidity. A variety of medical therapies have been suggested for MP. Only two, thalidomide and low-dose naltrexone, have been prospectively evaluated. For patients with chronic MP, good responses to prolonged corticosteroid treatment have been reported. Novel therapies include thalidomide and low-dose naltrexone. Hormonal and immunomodulatory therapies are also used based on small case series, but these treatments may have significant side effects. Surgical intervention is not curative and is avoided except for relief of focal bowel obstruction secondary to fibrotic forms of the disease.

Sclerosing mesenteritis mimicking metachronous peritoneal metastases from descending colon adenocarcinoma

Background

Sclerosing mesenteritis is a non-neoplastic inflammatory disease that occurs in the bowel mesentery. Distinguishing sclerosing mesenteritis from neoplasms may be difficult because of the clinical and radiographic similarities between the two disease entities.

Case presentation

We report a case of sclerosing mesenteritis mimicking peritoneal metastases of colorectal carcinoma. A 73-year-old man with stage II descending colon adenocarcinoma with poor prognostic features was found to have developed left lower abdominal quadrant masses on computed tomography (CT) 9 months after undergoing radical surgery. These masses were diagnosed as peritoneal metastases because they grew in size and displayed fluorodeoxyglucose (FDG) uptake 3 months later; thus, a laparotomy was performed. The masses, which were localized in the jejunal mesentery, were excised completely via segmental jejunal resection. Histopathological analysis confirmed that the masses were sclerosing mesenteritis. The patient showed no signs of sclerosing mesenteritis or colorectal carcinoma recurrence during follow-up.

Conclusions

In patients suspected of having localized peritoneal metastasis from malignancies, any masses must be sampled by surgical excisional biopsy and subsequently examined to rule out alternative diagnoses, such as sclerosing mesenteritis.

Clinical significance of mesenteric panniculitis-like abnormalities on abdominal computerized tomography in patients with malignant neoplasms

AIM

To clarify the association of malignancy with mesenteric panniculitis-like changes on computed tomography (CT).

METHODS

All abdominal CT scans performed at NorthShore University HealthSystem showing mesenteric panniculitis from January 2005 to August 2010 were identified in the Radnet (RadNet Corporation, Los Angeles, CA) database. Patients with a new or known diagnosis of a malignancy were included for this analysis. Longitudinal clinical histories were obtained from electronic medical records.

RESULTS

In total, 147794 abdominal CT scans were performed during the study period. Three hundred and fifty-nine patients had mesenteric panniculitis (MP)-like abnormalities on their abdominal CT. Of these patients, 81 patients (22.6%) had a known history of cancer at the time of their CT scan. Nineteen (5.3%) had a new diagnosis of cancer in concurrence with their CT, but the majority of these (14/19, 74%) were undergoing CT as part of a malignancy evaluation. Lymphomas were the most common cancers associated with MP-like findings on CT (36 cases, 36%), with follicular lymphoma being the most frequent subtype (17/36). A variety of solid tumors, most commonly prostate (7) and renal cell cancers (6) also were seen. CT follow up was obtained in 56 patients. Findings in the mesentery were unchanged in 45 (80%), worsened in 6 (11%), and improved in 5 patients (9%). Positron emission tomography (PET) scans performed in 44 patients only showed a positive uptake in the mesenteric mass in 2 patients (5%).

CONCLUSION

A new diagnosis of cancer is uncommon in patients with CT findings suggestive of MP. MP-like mesenteric abnormalities on CT generally remain stable in patients with associated malignancies. PET scanning is not recommended in the evaluation of patients with mesenteric panniculitis-like findings on CT.

Progressing Sclerosing Mesenteritis (Mesenteric Panniculitis) Mimics Progression of Malignancy After Neoadjuvant Chemotherapy for Gastric Adenocarcinoma on Serial 18F-FDG PET/CT

A 62-year-old man was diagnosed with a moderately differentiated gastric adenocarcinoma in the proximal stomach. A staging 18F-FDG PET/CT showed an intensely FDG-avid gastric mass, as well as a mildly FDG-avid misty nodular mesentery. After 3 cycles of neoadjuvant chemotherapy, a follow-up PET/CT showed partial response of the gastric primary, with increase in the size of nodules in the mesentery and increased FDG uptake, raising concern of secondary malignancy. Biopsy of the mesentery revealed xanthogranulomatous inflammation, consistent with sclerosing mesenteritis.

[A prospective study to determine the real value of mesenteric ¹⁸F-FDG uptake in cancer patients. inflammatory or tumoral mesenteric paniculitis?]

AIM

To assess the metabolic behavior of mesenteric panniculitis (MP), possible manifestation patterns in ¹⁸F-FDG PET/CT imaging and to discover if it is a reliable diagnostic method to differentiate tumor disease from inflammatory condition in this context.

MATERIAL AND METHODS

A total of 2,666 PET/CT scans were evaluated prospectively from April 2012 to August 2013. Thirty patients were included (37 scans) with radiological signs of MP. There were 8 women and 22 men, aged between 39 and 81 years, in the sample. According to the ¹⁸F-FDG uptake in the mesenteric lesions, expressed as SUVmax, patients were classified into two different groups: Group A consisted of 10 patients with increased uptake, SUVmax ≥ 2 or greater than the activity found in the surrounding healthy mesenteric tissue, and Group B (20 patients) SUVmax <2 or indistinguishable from healthy tissue.

RESULTS

No signs of mesenteric tumour involvement were demonstrated during a mean follow up of 13 months (false positives) in 80% of the Group A patients (mean SUVmax 7.11). Signs of the presence of tumor were only demonstrated in two patients of Group A (SUVmax 7.57 and 9.46) with a positive predictive value of 49.79%. All Group B patients were confirmed to be free of mesenteric involvement.

CONCLUSIONS

The presence of radiological signs of suggestive of MP, increase in glycidic metabolism, even intense and focal in these lesions, which may not exclude the possibility of an ongoing tumour process, would have a high likelihood of being indicative of intense inflammatory activity.

Mesenteric panniculitis in a child misdiagnosed as appendicular mass: a case report and review of literature

Mesenteric panniculitis is a chronic inflammatory process involving the adipose tissue of the mesentery. The etiology is unknown, and it is rare in children. We report a 5 year old girl who presented with abdominal symptoms and was misdiagnosed as appendicular mass. The correct diagnosis was established after surgical resection.

[Mesenteric panniculitis]

Mesenteric panniculitis is a nonspecific inflammatory process affecting the fatty tissue at the root of the mesentery. This term is also used to describe the clinical and imaging findings in this disorder. Mesenteric panniculitis can be a misleading term: it is commonly misused to design an increased density of the mesentery without prejudice regarding the etiology. Pain is the main clinical symptom. Half of the patients are asymptomatic. There is a palpable mass in half of cases. Laboratory tests sometimes reveal an acute phase reaction of varying intensity. Mesenteric panniculitis is suspected when CT scan shows increased density of the mesenteric fat. Nevertheless, only histological examination could establish the diagnosis. Histologic examination may reveal various stages: lipodystrophy (the first stage when fat necrosis is predominant), mesenteric panniculitis (a majority of infiltrating lymphocytes), sclerosing mesenteritis (the end stage when fibrosis is predominant). Histopathologic differential diagnoses are lymphomas, lipomas, liposarcomas that can mimic mesenteric panniculitis on CT scan. Mesenteric panniculitis is associated with various diseases, especially with intra-abdominal inflammatory process. It also can be idiopathic. Rare complications can occur with vascular or digestive tract compressions. Empirical treatment is only useful in symptomatic patients. Colchicine, corticosteroids or immunosuppressive agents can be used. The only interest of surgery is the histological confirmation of the diagnosis. A better understanding of the pathophysiology of the immunoregulatory functions of adipose tissue will improve mesenteric panniculitis management.

Mesenteric panniculitis presenting with acute non-occlusive colonic ischemia

BACKGROUND

The role of positron emission tomography (PET) of the mesentery as a diagnostic modality in cases of mesenteric panniculitis is unclear.

CASE PRESENTATION

A 67-year-old woman presented with rectal bleeding due to nonocclusive colonic ischemia. Abdominal CT showed features of mesenteric panniculitis. PET-CT demonstrated no abnormal fluorine-18 fluordeoxyglucose uptake in the affected mesentery or any surrounding lymph nodes. Laparoscopic biopsies from a thickened segment of mesenteric fat excluded neoplastic infiltration.

CONCLUSIONS

In cases of unexplained ischemic colitis, panniculitis should be considered a possible diagnosis. PET-CT may be negative for fluorine-18 fluordeoxyglucose uptake in this condition. As of known false-negative PET-CT results in mesenteric panniculitis, PET-CT has a limited role in the diagnostic work-up.