Maladie fibrosclérosante à IgG4

[A rare cause of eosinophilic asthma: Hyper-IgG4 syndrome (IgG4-related sclerosing disease)]

INTRODUCTION

The hyper-IgG4 syndrome is an emerging disease with various thoracic manifestations: eosinophilic asthma, adenomegalies or mediastinal fibrosis, asthma, infiltrative pneumonia, nodules or pseudo-tumors with bronchial and pleural localizations.

CASE REPORT

We report the case of a 38-year-old woman who was admitted for acute exacerbation of eosinophilic asthma with high total IgE levels. A medical history of idiopathic acute pancreatitis, associated with sclerosing cholangitis and renal failure, suggested a diagnosis of hyper-IgG4 syndrome in this woman with late-onset severe and non-atopic asthma. A previous hepatic histology and a reinterpretation of renal tomodensitometry have confirmed this hypothesis.

CONCLUSION

The hyper-IgG4 syndrome is responsible of different clinico-radiological patterns that should be evoked because of the pejorative evolution of this steroid sensitive disease.

Elevated IgG4 serum levels among primary Sjögren's syndrome patients: do they unmask underlying IgG4-related disease?

OBJECTIVE

To determine IgG4 levels in a cohort of consecutive patients with primary Sjögren's syndrome (SS) and other autoimmune diseases and explore whether they associate with distinct clinical, serologic, and histopathologic features.

METHODS

Serum IgG4 levels were measured in 133 primary SS patients and 49 healthy donors (HDs). Seventy-four lupus and 54 rheumatoid arthritis (RA) patients served as disease controls. Immunohistochemical IgG4 analysis was performed in paraffin-embedded minor salivary gland (MSG) tissues.

RESULTS

Raised IgG4 serum levels (>135 mg/dl) were detected in 10 (7.5%) of 133 primary SS patients (high-IgG4 group), in 8 (10.8%) of 74 lupus patients, in 7 (12.9%) of 54 RA patients, and in 1 (2%) of 49 HDs. Compared to the normal-IgG4 (<135 mg/dl) primary SS group, high-IgG4 patients exhibited increased prevalence of IgG4-related features (autoimmune cholangitis, autoimmune pancreatitis, and interstitial nephritis), lower rates of antinuclear antibody positivity, and higher IgG2 and IgE levels. Positive staining for IgG4+ plasma cells with an IgG4:IgG ratio ≥40% was detected in 3 of 6 available MSG tissues in the high-IgG4 group. Criteria of possible or definite IgG4-related disease (IgG4-RD) were fulfilled by 10 (7.5%) of 133 of our primary SS cohort.

CONCLUSION

Raised IgG4 serum levels were detected in 7.5% of primary SS patients in association with IgG4RD-reminiscent clinical, serologic, and histopathologic features. Whether this high-IgG4 primary SS group represents a misclassified IgG4-RD group or a distinct primary SS subtype remains to be further explored in future studies.

[Hypophysitis: increasingly complex clinicopathological spectrum!]

Hypophysitis is a chronic inflammation of the pituitary gland that comprises an increasingly complex clinicopathological spectrum. Lymphocytic and granulomatous hypophysitis are the most common forms, but new variants have recently been reported such as IgG4-related hypophysitis that is identified by well-defined criteria. For the first time, hypophysitis in ANCA-associated vasculitides has been reported. Monoclonal antibodies directed against the cytotoxic T-lymphocyte antigen-4 (CTLA-4), investigated in metastatic melanoma, can induce hypophysitis. Hypophysitis's pathogenesis remains obscure but several candidate pituitary autoantigens have been described in the last decade, although none has proven useful as a diagnostic tool.

[Acute pulmonary edema, new complication of sclerosing mediastinitis]

Sclerosing mediastinitis is a rare and benign disease, which can cause obstruction of mediastinal structures, this determines the clinical presentation and prognosis. The obstruction of pulmonary venous structures secondary to mediastinal fibrosis has been rarely reported, clinically it mimics mitral stenosis. We describe the clinical case of a young patient with idiopathic sclerosing mediastinitis. The radiologic exams found stenosis of the right pulmonary artery, the right bronchus and pulmonary veins. Through this observation, we discuss this rare entity that although benign, can also be deadly. We study the different etiologies, clinical and therapeutic possibilities.

[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.