[1865] Comparison of the Immunohistochemical Staining Methods for the Diagnosis of Lymphoplasmacytic Sclerosing Pancreatitis

Katsuyuki Miyabe, Kenji Notohara, Takahiro Nakazawa, Kaduki Hayashi, Itaru Naitoh, Fumihiro Okumura, Shuya Shimizu, Michihiro Yoshida, Hiroaki Yamashita, Hirotaka Ohara, Takashi Joh. Nagoya City University, Nagoya, Japan; Kurashiki Central Hospital, Kurashiki, Japan

Background: Presence of abundant IgG4-positive plasma cells is a significant pathologic finding for the diagnosis of lymphoplasmacytic sclerosing pancreatitis (LPSP), or type 1 autoimmune pancreatitis. Various methods to evaluate the immunohistochemical stains have been proposed. However, these methods have not been compared so far.
Design: Resected or open biopsy specimens of LPSP (18 patients), chronic pancreatitis (CP; 24), and pancreatic ductal adenocarcinoma (PDA; 45) were evaluated. In each case, serial sections were made from a representative block for H&E stain and immunostaining for IgG, IgG1, IgG4, and CD138. The number of immunostaing-positive cells was counted in 10 high power fields (HPFs) by selecting fields with the most numerous positive cells (Method A), or by selecting fields randomly in the affected areas (Method B). We evaluated 1) mean number of IgG4-positive plasma cells/HPF, 2) number of fields with ≥11 IgG4-positive plasma cells, and 3) IgG4/ IgG1 ratio (total number of IgG4-positive plasma cells/ total number of IgG1-positive plasma cells), 4) IgG4/ IgG ratio, and 5) IgG4/ CD138 ratio. The best cutoff values and area under curve (AUC) to differentiate LPSP from CP and PDA were evaluated by receiver operator characteristic (ROC) curve and AUCs of these five groups were compared within each Method and between Method A and B.
Results:

Outcome analyzed ROC curves

	Method A			Method B
	Cutoff value	Sensivity/ Specifity	AUC	Cutoff value	Sensivity/ Specificity	AUC
1) mean IgG4-positive plasma cells	54.6	94.4%/ 92.8%	0.9782	34.9	83.3%/ 100%	0.9744
2) number of fields with ≥11 IgG4-positive plasma cells	10	100%/ 79.7%	0.8929	6	94.4%/ 97.1%	0.9828
3) IgG4/ IgG1	1.082	88.9%/ 87.0%	0.9235	0.903	94.4%/ 90.3%	0.9370
4) IgG4/ IgG	0.197	88.9%/ 49.3%	0.6857	0.332	100%/ 81.2%	0.9143
5) IgG4/ CD138	0.487	100%/ 21.7%	0.4303	0.424	88.9%/ 76.8%	0.8534

In 2), 4) and 5), Method B had significantly higher AUCs than Method A. Compared within each Method, 1) and 3) had higher AUCs in Method A whereas 1), 2), and 3) had higher AUCs in Method B.
Conclusions: For the diagnosis of LPSP, immunostaing-positive cells should be counted by selecting fields randomly in the affected areas. More than 5 of 10 HPFs with ≥11 IgG4-positive plasma cells by choosing fields randomly in the affected areas is a useful and simple diagnostic method for LPSP, although counting number of IgG4 or IgG4/ IgG1 ratio are highly diagnostic.
Category: Pancreas

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 260, Tuesday Morning