Background Adult onset Still's disease (AOSD) is characterized by fever, skin rash, and lymphadenopathy with leukocytosis and anemia as common laboratory findings. The cutaneous pathology previously described is nonspecific in AOSD. In contrast to nonspecific cutaneous pathology, characteristic lymph node histology of AOSD was described in several reports. The other clinical manifestations are related to hepatic dysfunction and hematologic abnormalities. However, there are limited reports on liver and bone marrow pathology in patients with AOSD; the histopathologic findings of these organs in AOSD are not well established.
Objectives We investigated characteristic pathologic findings of skin, lymph node, liver and bone marrow to assist in proper diagnosis of AOSD.
Methods Forty AOSD patients were included in the study. The skin (26 patients), lymph node (8 patients), liver (8 patients) or bone marrow biopsies (22 patients) between 1998 and 2013 were retrospectively analyzed. AOSD patients were diagnosed according to Yamaguchi's criteria after exclusion of common infections, hematological and autoimmune diseases. Immunohistochemistry, immunofluorescence, and Epstein-Barr virus-encoded RNA (EBER) in situ hybridization were performed.
Results Most skin biopsies revealed mild lymphocytic or histiocytic infiltration in the upper dermis. Nuclear debris were frequently found on the dermis in 14 cases (53.8%). More than half of the cases (n=14, 53.8%) showed interstitial mucin deposition. Some cases showed interface dermatitis with keratinocyte necrosis or basal vacuolization (n=10; 38.5%). The lymph node showed paracortical or diffuse hyperplasia pattern with immunoblastic and vascular proliferation. The liver biopsies showed sparse portal and sinusoidal inflammatory cell infiltration. All cases had various degrees of Kupffer cell hyperplasia. The cellularities of bone marrow varied from 20% to 80%. Myeloid cell hyperplasia was found in 14 of 22 cases (63.6%). On immunohistochemistry, the number of CD8-positive lymphocytes was larger than the CD4-positive lymphocytes in skin, liver and bone marrow, but the number of CD4-positive lymphoctes was larger than the CD8-positive lymphocytes in the lymph node.
Conclusions We found that the pathologic findings of liver and bone marrow were rather nonspecific. However, skin and lymph node pathology in addition to clinical findings can help with the diagnosis of AOSD.
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Disclosure of Interest None declared