Differentiation Between Disseminated Carcinomatosis of the Bone Marrow From Urothelial Cancer and Intravascular Large B-cell Lymphoma: A Case Report.

This case report describes a rare case of intravascular large B-cell lymphoma (IVLBCL), initially presenting with nonspecific symptoms of fever and fatigue, and tentatively diagnosed as disseminated carcinomatosis of the bone marrow originating from urothelial cancer in an 80-year-old woman. The patient's journey began with symptoms treated as common ailments and progressed through multiple differential diagnoses, including giant cell arteritis, TAFRO (thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly) syndrome, and disseminated carcinomatosis of the bone marrow originating from urothelial cancer due to the presence of systemic inflammation, anasarca, and elevated soluble interleukin 2 receptor levels, indicative of an intense immunological response. Despite initial treatments, her condition deteriorated, leading to further investigations that ultimately revealed the presence of malignant cells in the urine and bone marrow, confirming the diagnosis of IVLBCL. This case underscores the diagnostic challenges faced when elderly patients present with systemic inflammation and the critical need for thorough investigation beyond initial impressions. It highlights the importance of considering differentiation between disseminated carcinomatosis of the bone marrow and IVLBCL in the differential diagnosis of persistent inflammation, especially in cases where common causes have been excluded and the primary malignancy is not immediately apparent.