Differential Diagnosis
The patient's presentation of low-grade fever, new onset normocytic anemia, elevated LDH, and ferritin, along with fatigue, suggests a range of possible diagnoses. Here's a categorized differential diagnosis:
Single Most Likely Diagnosis
- Myelodysplastic Syndrome (MDS): The combination of normocytic anemia, elevated LDH, and significantly elevated ferritin in a 90-year-old patient, without lymphadenopathy, points towards MDS. The normal reticulocyte count and absence of lymphadenopathy also support this diagnosis, as MDS often presents with ineffective erythropoiesis and a lack of significant lymphoid involvement.
Other Likely Diagnoses
- Chronic Lymphocytic Leukemia (CLL): Although lymphadenopathy is typically present, some cases of CLL can be lymphadenopathy-free at diagnosis. The elevated LDH and anemia could be consistent with CLL, especially if there's an associated autoimmune hemolytic anemia.
- Myeloproliferative Neoplasm (MPN): Certain MPNs, like primary myelofibrosis, can present with anemia, elevated LDH, and ferritin. However, the lack of significant splenomegaly or other cytopenias makes this less likely.
- Chronic Myelomonocytic Leukemia (CMML): This could be considered given the anemia and elevated LDH, but typically, CMML presents with monocytosis, which is not mentioned.
Do Not Miss Diagnoses
- Lymphoma: Although less likely given the lack of lymphadenopathy, certain types of lymphoma (e.g., diffuse large B-cell lymphoma) can present with systemic symptoms like fever and anemia. Missing a diagnosis of lymphoma could be catastrophic due to its potential for rapid progression.
- Acute Leukemia: The presence of anemia, elevated LDH, and a significantly elevated ferritin could also suggest acute leukemia, particularly if there's a blast crisis. This diagnosis is critical to identify promptly due to its aggressive nature and need for immediate treatment.
- Hemophagocytic Lymphohistiocytosis (HLH): This rare condition can present with fever, anemia, elevated ferritin, and LDH. It's often associated with a high mortality rate if not recognized and treated early.
Rare Diagnoses
- Paroxysmal Nocturnal Hemoglobinuria (PNH): This condition could explain the anemia and elevated LDH, but it's relatively rare and typically presents with hemolytic anemia and possibly thrombosis.
- Pure Red Cell Aplasia: This could be a consideration for the anemia, but the elevated LDH and ferritin levels, along with the lack of reticulocytosis, make it less likely.
- Erythroleukemia: A subtype of acute myeloid leukemia, it presents with anemia and could have elevated LDH and ferritin, but it's rare and typically associated with other cytopenias and blast cells in the peripheral blood or bone marrow.