Background: Primary bladder lymphoma is generally regarded as having a favorable prognosis due to the predominance of low-grade lymphomas confined to the bladder. However, our investigation reveals that cases with extravesical extension, predominantly involving diffuse large B-cell lymphoma (DLBCL), exhibit a distinct clinical course with varied prognostic outcomes. Methods: In this report, we present and analyzed the clinical features and outcomes of 47 patients with primary bladder lymphoma with extravesical extension, including the case that we experienced. Results: An 77-year-old man who experienced fever, anorexia, and general malaise was referred to our hospital. Initial laboratory tests indicated severe renal failure, pyuria, and Escherichia coli bacteremia, accompanied by diffuse thickening of the bladder walls and increased attenuation in the surrounding adipose tissues. Initially misdiagnosed with a severe urinary tract infection leading to sepsis, the patient was treated with antibiotics and hemodialysis. Upon readmission due to abdominal pressure, imaging identified an intra-abdominal mass connected to the bladder wall. A bladder biopsy was performed, resulting in the diagnosis of primary bladder DLBCL with perivesical extension, classified as germinal center B-cell type. Taking inspiration from this case, the review of 46 patients was implemented. As a result, we resolved that primary bladder lymphoma often includes indolent types like Mucosa-associated lymphoid tissue lymphoma, but cases with extravesical expansion are predominantly DLBCL. Conclusions: This case emphasizes the diagnostic complexities of distinguishing primary bladder lymphoma from urinary tract infections and underscores the prognostic implications of extravesical extension. Our comprehensive review of the literature on primary bladder lymphomas with extravesical involvement highlights the clinical characteristics, therapeutic challenges, and need for heightened diagnostic vigilance and tailored treatment strategies for this subset of patients.

Suspected immune thrombotic thrombocytopenic purpura (iTTP) creates a dual emergency: treatment must begin before ADAMTS13 confirmation, while lethal mimics must be investigated concurrently. A 44-year-old woman presented with fever, severe thrombocytopenia, progressive limb weakness, and multifocal cerebral infarctions. Although the schistocyte proportion was <1% and her PLASMIC score was 5, iTTP could not be safely excluded. ADAMTS13 activity was sampled before treatment, and plasma exchange plus corticosteroids was started. Blood cultures grew methicillin-susceptible Staphylococcus aureus. Despite three negative transthoracic echocardiograms, transesophageal echocardiography demonstrated a 10-mm mitral vegetation, establishing infective endocarditis (IE). Pretreatment ADAMTS13 activity was 35%, allowing TTP-directed therapy to be withdrawn. IE can produce thrombocytopenia, microangiopathic hemolysis, TMA-like presentations, and occasionally marked ADAMTS13 reduction; conversely, schistocytes may be initially inapparent in true iTTP. Thus, neither a low schistocyte count nor an intermediate prediction score should end diagnostic reasoning. When iTTP and IE remain plausible, pretreatment ADAMTS13 sampling, risk-adapted empiric TTP therapy, blood cultures, antimicrobial treatment, and definitive cardiac imaging should proceed in parallel.