Purpose: We classified underlying diseases presenting as inflammation of unknown origin in division of rheumatic diseases. On the other hand, patients with malignant lymphoma (ML) varying in cause and symptoms are often admitted to our Rheumatology Division as cases of malignant disease presenting with fever of unknown origin.
Patients and methods: Clinical records over 5 years were reviewed for 246 cases of undiagnosed inflammatory diseases at hospitalization.
Results: The 246 patients included 76 patients with infection, 116 with rheumatic disease, 8 with solid cancer, 9 with drug-induced fever, 10 with other disorders, and 27 with suspected ML. Of theses, malignant lymphoma (ML) was diagnosed in 20 patients (5 Mature T-cell and NK-cell neoplasms, 3 Hodgkin lymphomas, and 12 Mature B cell neoplasms including 5 Intravascular large B-cell lymphoma (IVLBCL)). The reasons for hospitalization were underlying collagen disease in 6 patients, medical workup for fever of unknown origin in 8 patients, and symptoms suggestive of collagen disease in 6. Nearly all of these patients presented with fever and other B symptoms, frequently with concurrent hypoxemia and hemophagocytic syndrome in IVLBCL. For diagnostic purposes, biopsy sites were determined by 18 fluorodexyglucose-positron emission tomography and computed tomography (FDG-PET/CT) in 13 patients, and findings on random skin biopsies were diagnostic in 3 of 5 patients with IVLBCL. Laboratory data on patients with B-cell lymphoma or peripheral T-cell lymphoma revealed tendencies for thrombocytopenia, elevated serum LDH, and increased soluble interleukin-2 receptor (sIL-2R). High serum ferritin values were more frequent in IVLBCL than in other B-cell lymphomas.
Conclusion: ML ranked first among causes of inflammation of unknown origin at the division of Rheumatic Diseases, and FDG-PET/CT proved to be useful for biopsy site selection. IVLBCL was not uncommon, and our results show the usefulness of clinical features and random skin biopsies for rapid diagnosis.