Diagnosis of Intermittent Fever with Pulmonary Opacities: A Case Report of Pulmonary Primary Intravascular Large B-cell Lymphoma with Aspergillosis and Non-Tuberculous Mycobacterial Pulmonary Disease

Background Intravascular Large B‑cell Lymphoma (IVLBCL) is a rare type of aggressive extranodal non-Hodgkin lymphoma (NHL), characterized by proliferation of B lymphoma cells within blood capillary lumina. Primary pulmonary IVLBCL is a rare sub-type of IVLBCL, presenting symptoms similar to community acquired pneumonia and other pulmonary infectious diseases. Case Presentation A 55-year-old women presented to ward with repeated fever. Physical examination found patient had dyspnea and hypoxemia, and laboratory findings showed an increased level of lactate dehydrogenase (1092 U/L) and soluble interleukin-2 receptor (3879 U/mL). Microbiology examinations detected Aspergillus in Bronchoscopy samples, but the fever continued to present after antibiotic treatment. Pathological examination found nests of atypical cells and confirmed IVLBCL after immunohistochemical stain. Further mycobacterial culture reported NTM positive results, and the patient experienced clinical improvement after receiving R-CHOP chemotherapy. Conclusions: This case described a situation that a patient presenting with fever and pulmonary lesions may actually came with infectious diseases overlapped with unrecognized hematological malignancy, which should be considered in differential diagnoses especially when patients do not respond well to antibiotic treatments. PET-CT plays an important role in diagnosing patients with fever, but may be misled by clinical microbiology results. Primary Pulmonary IVLBCL does not have a specific clinical manifestation, sometimes shows symptoms similar to pulmonary infectious diseases, and is usually confirmed by pathological diagnosis. mNGS has a great sensitivity in detecting microbes in clinical practice, but the diagnosis should always be careful to made before excluding malignant diseases.