FRI0593 PATHOLOGICAL FEATURES OF LYMPH NODE IN JAPANESE PATIENTS WITH ADULT-ONSET STILL’S DISEASE

Background Adult-onset Still’s disease (AOSD) rarely occurs in adults and no specific serological or pathological findings have ever been reported. Although multiple lymphadenopathy often develops in AOSD patients, only few reports have described their pathology so far.1,2 Objectives To examine pathological features of lymph node (LN) in AOSD patients and their usefulness in diagnosis in Japan. Methods This is a single center, retrospective study. The subjects were 115 Japanese patients who visited our department and received LN biopsy from April 2010 to July 2018. Of these, 12 patients, in whom AOSD was suspected by clinicians at the time of biopsy, were analyzed. AOSD patients were diagnosed according to the Yamaguchi’s criteria3, except the item “excluding malignant lymphoma”. Results The median age of the 12 cases (2 males, 10 females) was 60.5 years old (range: 18-81). Paracortical hyperplasia was shown in 7, follicular hyperplasia in 1, histiocytic necrotizing lymphadenitis (HNL) in 3, and diffuse large B cell lymphoma (DLBCL) in 1. Of 9 who fulfilled Yamaguchi’s criteria, TAFRO syndrome was diagnosed in one. As for the other 8, diagnosis of AOSD was made and successfully treated as AOSD. Although 1 of the 8 had pathological features of HNL, we treated her as AOSD because her clinical feature and laboratory data were not compatible with HNL. As for the 3 who did not meet the criteria, their clinicopathological diagnosis was HNL in 2 and DLBCL in 1. We could find no associations between the clinical features and lymph node patterns in AOSD as previously reported. Conclusion In patient who fulfilled the criteria, most cases showed paracortical hyperplasia in LN as previously reported from outside Japan and no cases had malignant lymphoma. However, in diagnosing AOSD, LN biopsy is needed to exclude AOSD-mimicking malignant lymphoma especially in the case that does not fulfill the criteria. References [1] Kim HA, et al. Medicine (Baltimore). 2015;94:e787. [2] Jeon YK, et al. J Clin Pathol. 2004;57:1052. [3] Yamaguchi M, et al. J Rheumatol1992;19:424–30. Disclosure of Interests None declared