AB1162 Diagnostic utility of lymph node biopsy in differential diagnosis of igg4-related disease, idiopathic multicentric castleman’s disease and primary disseminated malt-lymphoma

Background Lymphadenopathy (LA) is a frequent and challenging syndrome in rheumatic patients. It requires comprehensive clinical and expert pathological evaluation. IgG4-related disease (IgG4-RD) combines a group of fibroinflammatory conditions characterised by formation of tumor-like lesions with unique morphological features and hyper-IgG4 secretion in different organs and tissues. LA is frequent in IgG4-RD and doesn’t have a unique morphology. Idiopathic multicentric Castleman’s disease (iMCD) is a rare lymphoprolipherative disorder of a hyper-IL-6 spectrum with obligate lymph nodes (LN) affection and less frequent extranodal lesions. Pathologic features of the LN in iMCD overlap with IgG4-LA and there can be IgG4 hypersecretion in iMCD patients as well. Primary disseminated MALT-lymphomas (DMALT) are also in the spectrum of differential diagnosis because of the involvement of salivary and lacrimal glands. Objectives To evaluate the diagnostic utility of LN biopsy in differential diagnosis of IgG4-RD, iMCD and DMALT. Methods Retrospective study. We reviewed medical records from 2009 to 2017 and identified 13 pts. who were examined in our clinic due to some rheumatological diagnosis suspicion and whose leading symptom at the onset of the disease was LA. All patients had prior multiple LN biopsy (25 LN biopsies in total) which was reviewed by an expert pathologist during our examination. 11 pts. had extranodal lesions and underwent extranodal biopsy. Results Eight pts. were men, 5 women with average age at the onset 34,7 years (15–71 years). The directional diagnoses established on the LN pathology were as following (in some cases a few diagnosis): iMCD (4 pts), non-Hodgkin lymphoma (3 pts), reactive LN (12 pts). 11 pts. had some extranodal lesions (3,9 per patient, from 1 to 8): orbit – 8, major salivary glands – 8, hepatosplenomegaly – 5, lungs – 5, thyroid – 5, kidneys – 3, sinusitis – 3, skin, cholangitis – 2 each, retroperitoneum, mediastinum, pancreas and soft tissues – 1 each. Due to orbital and major salivary glands involvement some patients had directional diagnosis of Sjogren’s syndrome or IgG4-RD. In all 13 pts. the directional diagnosis was changed to some other based on the extranodal biopsy pathology results (in 11 pts) and/or clinical presentation (in 2 pts with isolated LA). LN pathology was not conclusive in all cases. In all cases LN phathology fell into I-IV type of LN morphological picture as reported by J. Ferry et al. 1 Clinical presentation in 13 pts see in table 1. The final diagnosis were: IgG4-RD in 7 pts, iMCD in 2 pts and DMALT in 4 pts. Conclusions It seems to be very challenging to set a reliable differential diagnosis based on the LN pathology thus extranodal biopsy is preferable. Orbital and major salivary glands involvement is a feature of IgG4-RD or DMALT, but not iMCD. Prominent constitutional symptoms with high laboratory inflammatory markers (CRP, IL-6) are characteristic of iMCD. Reference [1] Ferry, J. IgG4-related lymphadenopathy and IgG4-related lymphoma: moving targets//Diagnostic Histipathology. —2013.—Vol. 19.—№ 4.—P. 128–139 Disclosure of Interest None declared