Table 3.
Japanese Clinical Diagnostic Criteria for Autoimmune Pancreatitis, 2018 [21]
| Diagnostic criteria |
| A. Diagnostic items |
| I. Enlargement of the pancreas |
| a. Diffuse enlargement |
| b. Segmental/focal enlargement |
| II. Imaging findings showing irregular narrowing of the main pancreatic duct |
| a. ERP (endoscopic retrograde pancreatography) |
| b. MRCP (magnetic resonance cholangiopancreatography) |
| III. Serological findings |
| Elevated serum IgG4 (≧ 135 mg/dl) |
| IV. Pathological findings among 1 ~ 5 listed below |
| a. Three or more of 1 ~ 4 are observed |
| b. Two of 1 ~ 4 are observed |
| c. 5 is observed |
| 1. Prominent infiltration of lymphocytes and plasma cells along with fibrosis |
| 2. More than 10 IgG4-positive plasma cells per high-power microscopic field |
| 3. Storiform fibrosis |
| 4. Obliterative phlebitis |
| 5. No neoplastic cells detectable by EUS-FNA (endoscopic ultrasound-guided fine-needle aspiration biopsy) |
| V. Extrapancreatic lesions including sclerosing cholangitis, sclerosing dacryoadenitis/sialoadenitis, retroperitoneal fibrosis, and kidney lesion |
| a. Clinical lesions |
| Extrapancreatic sclerosing cholangitis, sclerosing dacryoadenitis/sialoadenitis (Mikulicz disease), retroperitoneal fibrosis, or kidney lesion detectable by clinical and imaging findings |
| b. Pathological lesions |
| Pathological examination showing characteristic features of sclerosing cholangitis, sclerosing dacryoadenitis/sialoadenitis, retroperitoneal fibrosis, or kidney lesion |
| VI. Effectiveness of steroid therapy |
| A specialized facility may include in its diagnosis the effectiveness of steroid therapy once pancreatic and bile-duct cancers have been ruled out. When it is difficult to differentiate malignant conditions, cytological examination using EUS–FNA (IVc) is desirable. Facile therapeutic diagnosis by steroid responsiveness alone should be avoided unless the possibility of malignant tumor has been ruled out by pathological diagnosis. Accordingly, VI includes IVc |
| B. Diagnosis |
| I. Definite diagnosis |
| 1. Diffuse type |
| Ia + < III/IVb/V (a/b) > |
| 2. Segmental/focal type |
| Ib + IIa + two or more of < III/IVb/V (a/b) |
| or |
| Ib + IIa + < III/IVb/V (a/b) > + VI |
| or |
| Ib + IIb + < III/V (a/b) > + IVb + VI |
| 3 Definite diagnosis by histopathological study IVa |
| II. Probable diagnosis |
| Segmental/focal type: Ib + IIa + < III/IVb/V (a/b) > |
| or |
| Ib + IIb + < III/V (a/b) > + IVc |
| or |
| Ib + < III/IVb/V (a/b) > + VI |
| III. Possible diagnosis* |
| Diffuse type: Ia + II (a/b) + VI |
| Segmental/focal type: Ib + II (a/b) + VI |
*Possible diagnosis: a case may possibly be type 2, although this is extremely rare in Japan. For section B, “ + ” indicates “and” and “/” indicates “or”