자가면역췌장염의 진단

 

자가면역췌장염의 진단은 다른 진단을 배제한 후 혈청학적 검사 (IgG4 상승)과 영상검사를 바탕으로 조직검사에 근거합니다. 췌장 실질과 췌관에 대한 영상 검사, 혈청학적 검사, IgG4-RD와 관련된 OOI, 췌장 조직학, 스테로이드 치료에 대한 반응으로 자가면역췌장염을 진단하고 분류합니다. 진단은 전통적으로 HISORt (histology, imaging, serology, other organ involvement, and response to steroid therapy) criteria라고 불렀습니다. 자가면역췌장염의 진단과 하위 분류는 특정 소견에 기초하여 definitive 또는 probable로 간주됩니다.

 

자가면역췌장염의 진단 기준은 민감도가 85%로 제한적이므로 임상의는 다른 질환 가능성을 항상 고려해야 합니다. 예를 들면 췌장암입니다. 따라서 스테로이드에 대한 반응이 없다면 재평가해야 합니다.

 

 

자가면역 췌장염의 진단기준

Criterion		Level 1	Level 2
P	Parenchymal imaging	Typical: ■ Diffuse enlargement with delayed enhancement (sometimes associated with rim-like enhancement)	Indeterminate (including atypical*): ■ Segmental/focal enlargement with delayed enhancement
D	Ductal imaging (ERP)	Long (greater than one-third length of the main pancreatic duct) or multiple strictures without marked upstream dilatation	Segmental/focal narrowing without marked upstream dilatation (duct size, <5 mm)
S	Serology	IgG4, >2× upper limit of normal value	IgG4, 1 to 2× upper limit of normal value
OOI	Other organ involvement	a or b	a or b
		a. Histology of extrapancreatic organs Any three of the following: 1. Marked lymphoplasmacytic infiltration with fibrosis and without granulocytic infiltration 2. Storiform fibrosis 3. Obliterative phlebitis 4. Abundant (>10 cells/HPF) IgG4-positive cells b. Typical radiologic evidence At least one of the following: 1. Segmental/multiple proximal (hilar/intrahepatic) or proximal and distal bile duct stricture 2. Retroperitoneal fibrosis	a. Histology of extrapancreatic organs including endoscopic biopsies of bile duct¶ Both of the following: 1. Marked lymphoplasmacytic infiltration without granulocytic infiltration 2. Abundant (>10 cells/HPF) IgG4-positive cells b. Physical or radiologic evidence At least one of the following: 1. Symmetrically enlarged salivary/lachrymal glands 2. Radiologic evidence of renal involvement described in association with AIP
H	Histology of the pancreas	LPSP (core biopsy/resection)	LPSP (core biopsy)
		At least 3 of the following: 1. Periductal lymphoplasmacytic infiltrate without granulocytic infiltration 2. Obliterative phlebitis 3. Storiform fibrosis 4. Abundant (>10 cells/HPF) IgG4-positive cells	Any 2 of the following: 1. Periductal lymphoplasmacytic infiltrate without granulocytic infiltration 2. Obliterative phlebitis 3. Storiform fibrosis 4. Abundant (>10 cells/HPF) IgG4-positive cells
Response to steroid (Rt)Δ		Diagnostic steroid trial
		Rapid (≤2 weeks) radiologically demonstrable resolution or marked improvement in pancreatic/extrapancreatic manifestations

 

AIP: autoimmune pancreatitis; ERP: endoscopic retrograde pancreatogram; IgG4: immunoglobulin G4; HPF: high-power field; LPSP: lymphoplasmacytic sclerosing pancreatitis.

* Atypical: Some AIP cases may show low-density mass, pancreatic ductal dilatation, or distal atrophy. Such atypical imaging findings in patients with obstructive jaundice and/or pancreatic mass are highly suggestive of pancreatic cancer. Such patients should be managed as pancreatic cancer unless there is strong collateral evidence for AIP, and a thorough workup for cancer is negative (refer to UpToDate topic on autoimmune pancreatitis).

¶ Endoscopic biopsy of duodenal papilla is a useful adjunctive method because ampulla often is involved pathologically in AIP.

Δ Diagnostic steroid trial should be conducted carefully by pancreatologists only after negative workup for cancer. Refer to UpToDate content on autoimmune pancreatitis for additional details.

Ref. UPTODATE 2022.06.05