A 41-year-old Caucasian man with a medical history of hypertension and an Eastern Cooperative Oncology Group performance status of 0 presented with abdominal pain, fatigue, and 10-pound weight loss for 2 months. He denied fevers or night sweats. On physical exam, the patient had bilateral inguinal lymphadenopathy up to 2 cm in diameter. Computed tomography (CT) scans revealed lymphadenopathy above and below the diaphragm and mild splenomegaly. Hemoglobin level was 13 g dL 21 (normal range: 13.5-16.0 g dL 21 ). The patient underwent an excisional biopsy of a left cervical lymph node and was discharged in stable condition.At this time, the differential diagnosis in this mildly anemic young man with weight loss and lymphadenopathy is very broad but includes infections and autoimmune processes. Oncologic conditions, such as lymphomas, should also be evaluated.He represented 1 week later with severe fatigue and hypotension. The patient had a hemoglobin of 5.5 g dL 21 , white blood cell count of 23.7 3 10 9 L 21 (normal range: 3.5-11.0 3 10 9 L
21), and platelet count of 123 3 10 9 L 21 (normal range: 150-400 3 10 9 L
21). The differential showed 55% neutrophils, 6% bands, 20% lymphocytes, 11% monocytes, 4% eosinophils, and 2% metamyelocytes. Patient denied hemoptysis, melena, or bright red blood per rectum. Two units of packed red blood cells (RBCs) were transfused with minimal increase in his hemoglobin levels.The hemoglobin level went from 13 to 5.5 g dL 21 in 1 week; this is an acute process. The differential includes acute bleeding or hemolysis. His blood counts also show leukocytosis and thrombocytopenia. Given the lack of response to transfusions, this could be an immune-mediated hemolytic phenomenon either primary or associated with an infectious process, such as acute EBV or Mycoplasma infection. The patient should also be worked up for gastrointestinal bleeding, although it is less likely the cause of such a marked decrease in his hemoglobin without evidence of frank hematochezia or melena.Additonal workup showed an elevated lactate dehydrogenase (LDH) level (663 IU L 21 ), reticulocytosis (8.2%), and undetectable haptoglobin (<5.8 mg dL 21 ). A peripheral blood smear did not show schistocytosis or spherocytosis but revealed circulating myelocytes, metamyelocytes, nucleated RBCs, and RBC agglutination. Fecal occult blood test was negative.This presentation is consistent with an acute acquired hemolytic process. The age of the patient makes congenital causes of hemolysis unlikely. The differential diagnosis includes autoimmune or drug-induced hemolysis and cryoglobulinemia. The presence of RBC agglutination supports the possibility of cryoglobulinemia. The lack of schistocytes does not support a microangiopathic process such as thrombotic thrombocytopenic purpura or disseminated intravascular coagulation. The concurrent presence of myeloid and erythroid precursors suggests a myelophthisic anemia, which could be associated with intramedullary hemolysis.Direct Coombs test was positive for immunoglobulin G (IgG)...