Progressive Pancytopenia in the Setting of Severe Pneumonia in a Patient With a History of Mantle Cell Lymphoma: A Case Report.

Progressive pancytopenia in a patient with a history of hematologic malignancy presents a diagnostic challenge because active hematologic disease and severe systemic illness can produce overlapping findings. We report a 74-year-old woman with previously treated mantle cell lymphoma who presented with fever, altered mental status, neutropenia, and multifocal pneumonia. During hospitalization, she developed rapidly progressive pancytopenia, prompting consideration of active hematologic disease, infection and critical illness, medication effects, and consumptive processes. Peripheral blood flow cytometry showed no immunophenotypic evidence of a lymphoproliferative disorder or acute leukemia. However, this finding did not establish the cause of the cytopenias. Her pneumonia progressed despite broad-spectrum antimicrobial therapy, and bronchoalveolar lavage cultures grew Stenotrophomonas maltophilia. She developed respiratory failure and shock requiring mechanical ventilation and vasopressor support, followed by refractory multiorgan failure. She died on hospital day 12. This case highlights the diagnostic challenge of rapidly progressive pancytopenia when severe pulmonary illness and a history of hematologic malignancy offer competing explanations. It emphasizes continual reassessment as serial hematologic and microbiologic findings reshape the differential diagnosis.