Pancreaticobiliary involvement in treated type 1 autoimmune pancreatitis: Imaging pattern and risk factors for disease relapse

Clinical characteristics and outcome of autoimmune pancreatitis based on serum immunoglobulin G4 level: A single-center, retrospective cohort study

BACKGROUND

Autoimmune pancreatitis (AIP) has been linked with elevated immunoglobulin (Ig) G4 levels. The characteristics and outcomes of AIP based on serum markers have not been fully evaluated.

AIM

To compare clinical features, treatment efficacy, and outcome of AIP based on serum IgG4 levels and analyze predictors of relapse.

METHODS

A total of 213 patients with AIP were consecutively reviewed in our hospital from 2006 to 2021. According to the serum IgG4 level, all patients were divided into two groups, the abnormal group (n = 148) with a high level of IgG4 [> 2 × upper limit of normal (ULN)] and the normal group (n = 65). The t-test or Mann-Whitney U test was used to compare continuous variables. Categorical parameters were compared by the χ2 test or Fisher's exact test. Kaplan-Meier curves and log-rank tests were established to assess the cumulative relapse rates. Univariate and multivariate analyses were used to investigate potential risk factors of AIP relapse.

RESULTS

Compared with the normal group, the abnormal group had a higher average male age (60.3 ± 10.4 vs 56.5 ± 12.9 years, P = 0.047); higher level of serum total protein (72.5 ± 7.9 g/L vs 67.2 ± 7.5 g/L, P < 0.001), IgG4 (1420.5 ± 1110.9 mg/dL vs 252.7 ± 106.6 mg/dL, P < 0.001), and IgE (635.6 ± 958.1 IU/mL vs 231.7 ± 352.5 IU/mL, P = 0.002); and a lower level of serum complement C3 (100.6 ± 36.2 mg/dL vs 119.0 ± 45.7 mg/dL, P = 0.050). In addition, a lower number of cases with abnormal pancreatic duct and pancreatic atrophy (23.6% vs 37.9%, P = 0.045; 1.6% vs 8.6%, P = 0.020, respectively) and a higher rate of relapse (17.6% vs 6.2%, P = 0.030) were seen in the abnormal group. Multivariate analyses revealed that serum IgG4 [(> 2 × ULN), hazard ratio (HR): 3.583; 95% confidence interval (CI): 1.218-10.545; P = 0.020] and IgA (> 1 × ULN; HR: 5.908; 95%CI: 1.199-29.120; P = 0.029) and age > 55 years (HR: 2.383; 95%CI: 1.056-5.378; P = 0.036) were independent risk factors of relapse.

CONCLUSION

AIP patients with high IgG4 levels have clinical features including a more active immune system and higher relapse rate. Several factors, such as IgG4 and IgA, are associated with relapse.

Challenges for clinicians treating autoimmune pancreatitis: Current perspectives

Autoimmune pancreatitis (AIP) is a rare disease clinically characterized by obstructive jaundice, unintentional weight loss, acute pancreatitis, focal pancreatic mass, and diabetes. AIP is classified into two subtypes - type 1 and type 2 - according to pathological findings, clinical features, and serology test results, but some cases may be defined as type not otherwise in the absence of pathological findings and inflammatory bowel disease. To address the differences in diagnostic criteria by country, standard diagnostic criteria for AIP were proposed in 2011 by an international consensus of expert opinions. Differential diagnosis of AIP from pancreatic ductal adenocarcinoma is important but remains challenging for clinicians. Fortunately, all subtypes of AIP show dramatic response to steroid treatment. This review discusses the current perspectives on the diagnosis and management of AIP in clinical practice.

Determination of the duration of glucocorticoid therapy in type 1 autoimmune pancreatitis: A systematic review and meta-analysis

BACKGROUND

The indications for maintenance glucocorticoid therapy (MGT) and its duration after initial remission of type 1 autoimmune pancreatitis (AIP) remain controversial. In contrast to the Japanese treatment protocol, the Mayo protocol does not recommend MGT after initial remission. This study aimed to evaluate the relapse rate in patients with type 1 AIP according to the duration of glucocorticoid therapy.

METHODS

We conducted a systematic literature review up until November 30, 2020, and identified 40 studies reporting AIP relapse rates. The pooled relapse rates were compared between groups according to the protocol and duration of glucocorticoids (routine vs. no MGT; glucocorticoids ≤6 months vs. 6-12 months vs. 12-36 months vs. ≥ 36 months). The pooled rates of adverse events related to glucocorticoids were also evaluated.

RESULTS

Meta-analysis indicated calculated pooled relapse rates of 46.6% (95% confidence interval (CI), 38.9-54.3%) with glucocorticoids for ≤ 6 months, 44.3% (95% CI, 38.8-49.8%) for 6-12 months, 34.1% (95% CI, 28.6-39.7%) for 12-36 months, and 27.0% (95% CI, 23.4-30.6%) for ≥ 36 months. The rate of relapse was also significantly lower in patients with routine-use protocol of MGT (31.2%; 95% CI, 27.5-34.8%) than in patients with no MGT protocol (44.1%; 95% CI, 35.8-52.4%). Adverse events were comparable between groups.

CONCLUSIONS

The rate of relapse tended to decrease with extended durations of glucocorticoid therapy up to 36 months. Clinicians may decide the duration of glucocorticoids according to patient condition, including comorbidities and risk of relapse.

DWI of Autoimmune Pancreatitis: Is It an Imaging Biomarker for Disease Activity?

OBJECTIVE. The purpose of this article was to evaluate the DWI features of autoimmune pancreatitis (AIP) at baseline, under treatment, and at relapse, and to assess the diagnostic accuracy of the ADC for determining disease activity. MATERIALS AND METHODS. This retrospective study was approved by the institutional review board. Sixty-two patients with AIP (48 at initial attack and 14 at relapse) underwent MRI with DWI (b = 0 and 800 s/mm²) at 3 T before receiving corticosteroid therapy (CST) and during follow-up. Seventeen patients had disease relapse during follow-up, whereas the others remained clinically stable. Forty age- and sex-matched patients without pancreatic disease served as the control group. RESULTS. The ADC value of AIP at baseline was significantly lower than that for a disease-free pancreas (0.99 ± 0.12 vs 1.26 ± 0.10 × 10^-3 mm²/s, p < .001). Under CST, the ADC value increased gradually at the short-term and long-term follow-up (1.16 ± 0.12 and 1.23 ± 0.12 × 10^-3 mm²/s, respectively, both p < .001). At relapse, the ADC had a relative decrease (1.11 ± 0.20 × 10^-3 mm²/s) but was significantly higher compared with the initial attack (p = .003). The AUC of ADC serum IgG4 level at ROC analysis for baseline versus clinically stable AIP was 0.867 and 0.700, the AUC for clinically active AIP versus clinically stable AIP was 0.762 and 0.686, and the AUC for relapsed AIP versus clinically stable AIP was 0.648 and 0.669. CONCLUSION. DWI reflected the dynamic change of AIP under CST, and the ADC value for DWI outperformed the serum IgG4 value for determining disease activity. However, relapsed disease showed less diffusion restriction, and the ADC value was less accurate for predicting relapse.

Clinical characteristics and long-term prognosis of autoimmune pancreatitis with renal lesions

Autoimmune pancreatitis (AIP) is recognized as the pancreatic manifestation of a systemic IgG4-related disease that can involve various organs, including the kidney. However, renal lesions tend to be overlooked when AIP is diagnosed, and the clinical characteristics and long-term prognosis of AIP with renal lesions are unclear. We retrospectively reviewed 153 patients with AIP diagnosed at our hospital with a median follow-up period of 41 months (interquartile range, 10–86) and classified them into two groups: the KD group (n = 17), with characteristic renal imaging features, and the non-KD group (n = 136). Serum IgG4 levels were significantly higher in the KD group (663 vs. 304.5 mg/dl, P = 0.014). No differences were observed between the two groups in terms of steroid treatment [14/17 (82.4%) vs. 112/136 (82.4%), P = 1] or in the number of patients who exhibited exacerbation of renal function during treatment [1/17 (5.9%) vs. 8/136 (5.9%), P = 1]. However, the cumulative relapse rate was significantly higher in the KD group [61% vs. 21.9% (3 years), P < 0.001]. Patients in the KD group had different clinical features with high relapse rates compared with those in the non-KD group, and thus, it is important to confirm the presence of renal lesions in AIP patients.

Risks and characteristics of pancreatic cancer and pancreatic relapse in autoimmune pancreatitis patients

BACKGROUND AND AIM

We examined the differences in the risks and characteristics of pancreatic relapse (PR) and pancreatic cancer (PC) in patients with autoimmune pancreatitis (AIP).

METHODS

We retrospectively reviewed 123 type 1 AIP patients with a median follow-up of 55 months (interquartile range, 27-98). The following items were evaluated: (i) cumulative relapse rates and risk factors, (ii) the incidence of PC, (iii) PR versus PC, and (iv) outcomes after the appearance of morphological changes in the pancreas (focal enlargement, apparent mass lesions, or main pancreatic duct dilation).

RESULTS

(i) The cumulative PR rates were 1.7% within 1 year, 11.5% within 3 years, and 22.6% within 5 years. Lack of maintenance therapy, IgG4-related sclerosing cholangitis, and IgG4-related kidney disease were identified as independent predictors of relapse. (ii) Two patients (1.6%) were diagnosed with PC at 17 and 22 months after initial AIP diagnosis. (iii) Thirteen (59.1%) and four (18.2%) patients with PR had focal enlargement and main pancreatic duct dilation, respectively. The median CA19-9 level at initial diagnosis was significantly higher in PC patients (21 vs 220.5 U/mL, P = 0.014). (iv) Eight PR patients underwent endoscopic ultrasound-guided fine-needle aspiration, none of whom had malignant findings. PC was diagnosed by ultrasound-guided fine-needle aspiration in both cancer patients.

CONCLUSIONS

Although the incidence of PC is low, it may mimic PR in AIP patients. Surveillance is important, and when morphological changes occur, biopsy and evaluation of serum IgG4 and CA19-9 levels (particularly if the levels were high before) should be considered.

Steroid Therapy and Steroid Response in Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP), a unique subtype of pancreatitis, is often accompanied by systemic inflammatory disorders. AIP is classified into two distinct subtypes on the basis of the histological subtype: immunoglobulin G4 (IgG4)-related lymphoplasmacytic sclerosing pancreatitis (type 1) and idiopathic duct-centric pancreatitis (type 2). Type 1 AIP is often accompanied by systemic lesions, biliary strictures, hepatic inflammatory pseudotumors, interstitial pneumonia and nephritis, dacryoadenitis, and sialadenitis. Type 2 AIP is associated with inflammatory bowel diseases in approximately 30% of cases. Standard therapy for AIP is oral corticosteroid administration. Steroid treatment is generally indicated for symptomatic cases and is exceptionally applied for cases with diagnostic difficulty (diagnostic steroid trial) after a negative workup for malignancy. More than 90% of patients respond to steroid treatment within 1 month, and most within 2 weeks. The steroid response can be confirmed on clinical images (computed tomography, ultrasonography, endoscopic ultrasonography, magnetic resonance imaging, and ¹⁸F-fluorodeoxyglucose-positron emission tomography). Hence, the steroid response is included as an optional diagnostic item of AIP. Steroid treatment results in normalization of serological markers, including IgG4. Short- and long-term corticosteroid treatment may induce adverse events, including chronic glycometabolism, obesity, an immunocompromised status against infection, cataracts, glaucoma, osteoporosis, and myopathy. AIP is common in old age and is often associated with diabetes mellitus (33-78%). Thus, there is an argument for corticosteroid therapy in diabetes patients with no symptoms. With low-dose steroid treatment or treatment withdrawal, there is a high incidence of AIP recurrence (24-52%). Therefore, there is a need for long-term steroid maintenance therapy and/or steroid-sparing agents (immunomodulators and rituximab). Corticosteroids play a critical role in the diagnosis and treatment of AIP.