Panniculite mésentérique et déficit immunitaire commun variable

[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.

[Sclerosing mesenteritis: can it be a IgG4 dysimmune disease?]

AIMS

Mesenteric panniculitis (MP), sclerotic mesenteritis (SM) and mesenteric lipodystrophy (ML) are the three histopathological forms of a rare inflammatory mesenteric disease. The pathogenesis is unknown until now. Hypothesis of a dysimmune disorder is advocated. Our purpose was to find histological basis to assert this hypothesis.

MATERIAL AND METHODS

All patients with a diagnosis of inflammatory mesenteric disease made in Beaujon hospital were selected. A histological study and a systematic immunostaining with IgG4, CD3 and CD8 antibodies were performed for each patient with paraffin block available. Dysimmune features were defined by: a plasma cells component >30 %, an eosinophilic polynuclears component >10 %, a rate TCD8/CD3 >30 % and IgG4+ plasma cells >30/high power field (x400). Cases were classified in 3 forms on the basis of the predominant component: MP (lymphoid/plasma cell infiltrate), SM (fibrosis), ML (fat necrosis).

RESULTS

Thirteen patients (7 men, 6 women) were selected, with a mean age of 57 years (21-80 years); a paraffin block was available for 10 patients. The clinical and histological presentations were heterogeneous: a mesenteric mass was the most frequent mode of revelation (6/13 patients) and all histological forms were present (3 MP, 5 SM and 5 ML). Nine patients had surgical biopsy, 2 had a trephine biopsy and 2 a resection. Standard histological analysis showed numerous eosinophils (> or =10 %) and plasma cells (>30 %) in respectively 3 (23 %) and 6 (46 %) of the 13 cases. The immunohistochemistry (performed in 10 patients) showed numerous TCD8+ in 80 % of the cases and numerous IgG4+ plasma cells in only 31 % of the cases (4 cases) (IgG4+ >30/x400).

CONCLUSIONS

Our results demonstrate that inflammatory mesenteric diseases are heterogeneous: high components of plasma cells, eosinophils and TCD8+ lymphocytes were found respectively in 46, 23 and 80 % of cases; eosinophils were observed exclusively in sclerotic forms. Only 31 % of cases encompass numerous IgG4+ plasma cells, suggesting a pathogenesis different than hyper-IgG4 diseases.

[Etiologic spectrum of mesenteric panniculitis: report of 7 cases]

OBJECTIVE

Mesenteric panniculitis is a rare disorder characterized by nonspecific inflammation and/or necrosis and/or fibrosis in the adipose tissue of the bowel mesentery. Its signification, primary or associated with other diseases, is a subject of controversy.

METHODS

A descriptive and retrospective study of patients with an abdominal CT examination showing features of mesenteric panniculitis and for whom biopsy with immunohistochemical examination was obtained in all cases.

RESULTS

Seven patients were enrolled (4 men and 3 women) with a median age of 62,1 years. None of the patients without an identified etiology had a history of abdominal surgery. An associated disease was identified in 4 cases: breast cancer (1), non-Hodgkin's lymphoma based on peripheric lymph nodes biopsy (2) and cryoglobulinemic vascularitis based on renal biopsy (1). In the 3 remaining cases, isolated mesenteric panniculitis was the only abnormality despite thorough imaging and pathologic investigations.

CONCLUSION

Except an obvious malignancy context or a history of abdominal surgery, a pathologic examination of the mesenteric panniculitis lesions is necessary, especially to eliminate another mesenteric disorder. Mesenteric panniculitis is often associated with lymphoma.