Differential Diagnosis for a 24-year-old Male with Fevers, Flank Pain, and Splenomegaly
- Single most likely diagnosis:
- Pyelonephritis or acute pyelonephritis with a slight elevation of creatinine, despite the absence of urinary findings, as the symptoms of flank pain and fever are consistent, and the slight elevation in creatinine and BUN could indicate renal involvement. However, the clear urine and lack of specific urinary symptoms make this less straightforward.
- Other Likely diagnoses:
- Infectious mononucleosis (mono) given the presence of fever, headache, and splenomegaly. The normal CBC does not rule out mono, as the CBC can be normal early in the disease.
- Viral hepatitis, although the chemistry panel is not fully provided, the slight elevation in creatinine could be seen in some cases of hepatitis, and splenomegaly can occur.
- Sepsis of another source (e.g., pneumonia, intra-abdominal infection) with secondary renal impairment, though the CT of the abdomen does not show an obvious source.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Sickle cell crisis, especially if the patient has sickle cell trait or disease, as it can cause renal impairment, pain episodes, and splenomegaly.
- Endocarditis, given the fever and splenomegaly, which could lead to renal emboli and impairment.
- Meningitis, as headache and fever could be indicative of this, and it's crucial to diagnose promptly.
- Rare diagnoses:
- Lymphoma, given the splenomegaly and systemic symptoms like fever, though this would be less likely without other specific findings like significant lymphadenopathy or abnormalities in the CBC.
- Systemic lupus erythematosus (SLE) or other autoimmune diseases, which can cause renal impairment, fever, and splenomegaly, though these diagnoses often require more specific findings and a longer history of symptoms.
- Brucellosis, a zoonotic infection that can cause fever, splenomegaly, and renal impairment, though it's relatively rare and usually associated with specific exposures.