Abstract Background Small cell lung carcinoma (SCLC) is an aggressive neuroendocrine tumor with early metastatic potential. While bone marrow involvement is not uncommon, clinically significant pancytopenia as the initial manifestation of marrow infiltration remains rare. Recognition of this pattern is crucial, as it portends advanced disease and poor prognosis. Case Presentation A 68-year-old man with a history of COPD and schizophrenia presented for newly identified lung masses. CT imaging revealed a right hilar mass, and bronchoscopy with endobronchial ultrasound-guided biopsy confirmed small cell lung carcinoma. Shortly thereafter, he developed hemoptysis requiring intubation and bronchoscopy with cryotherapy and argon plasma coagulation.His course was complicated by progressive anemia and thrombocytopenia refractory to transfusion. Peripheral smear revealed marked cytopenias without blasts. Bone marrow biopsy demonstrated diffuse effacement by metastatic small cell carcinoma, confirming marrow infiltration as the etiology. The patient developed recurrent acute hypoxemic respiratory failure requiring re-intubation, and shock necessitating vasopressor support. Given his instability, planned chemotherapy was deferred. Despite broad-spectrum antibiotics, stress-dose corticosteroids, and ventilatory support, his condition deteriorated. After multidisciplinary discussion, his family elected for comfort-focused care. Discussion SCLC frequently metastasizes to the liver, adrenals, bone, and brain, but symptomatic bone marrow involvement presenting as severe pancytopenia is uncommon. In this patient, marrow infiltration was responsible for profound cytopenias, complicating both diagnosis and management. This case underscores the importance of considering bone marrow metastasis in SCLC patients presenting with otherwise unexplained cytopenias, even early in the disease course. Recognition of this finding should prompt timely goals-of-care discussions, as marrow infiltration often indicates extensive disease and limited therapeutic options. Conclusion In summary, bone marrow metastasis should be considered in SCLC patients presenting with unexplained cytopenias, as it signifies extensive-stage disease and carries a poor prognosis. The development of pancytopenia from marrow involvement is associated with rapid clinical deterioration and underscores the importance of early recognition, timely goals-of-care discussions, and integration of palliative management, given the limited therapeutic options and unfavorable outcomes in this setting. This abstract is funded by: None
Espinoza et al. (2026) studied this question.