Differential Diagnosis

• Single most likely diagnosis
  • Infectious Mononucleosis: This condition, caused by Epstein-Barr virus (EBV), can lead to mesenteric lymphadenopathy, hepatitis (which might present with a "starry sky" pattern on ultrasound due to the presence of numerous small lymphoid infiltrates in the liver), and raised liver enzymes. The "starry sky" appearance is more commonly associated with Burkitt lymphoma but can be seen in other conditions as well. The symptoms of fever, fatigue, and lymphadenopathy, along with the laboratory findings of elevated liver enzymes and a high pulse rate, could align with infectious mononucleosis, especially in a young individual.
• Other Likely diagnoses
  • Viral Hepatitis: Various forms of viral hepatitis (A, B, C, etc.) can cause liver inflammation, leading to elevated liver enzymes and potentially a "starry sky" pattern on ultrasound, although this pattern is less commonly described in viral hepatitis. Mesenteric lymphadenopathy could be seen in the context of systemic infection.
  • Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can involve the liver and cause lymphadenopathy, including mesenteric lymph nodes. The "starry sky" pattern, while more classically associated with Burkitt lymphoma, could potentially be seen in other lymphomas affecting the liver.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis: Although the presentation might not fully align with sepsis, any condition causing significant systemic inflammation and organ dysfunction could potentially lead to a fatal outcome if not promptly recognized and treated. The high pulse rate and tenderness in the bilateral lumbar area could be indicative of a severe infection.
  • Hemophagocytic Lymphohistiocytosis (HLH): This rare but potentially fatal condition involves an overactive and inappropriate immune response, which can lead to liver dysfunction, lymphadenopathy, and other systemic symptoms. It's crucial to consider HLH in the differential diagnosis due to its high mortality rate if left untreated.
• Rare diagnoses
  • Burkitt Lymphoma: While mentioned earlier due to its association with the "starry sky" pattern, Burkitt lymphoma is a rare and aggressive form of non-Hodgkin lymphoma. It typically presents with rapid growth and can involve the liver, causing the described ultrasound findings.
  • Kikuchi-Fujimoto Disease: A rare, self-limiting condition that can cause lymphadenopathy and systemic symptoms, including fever and fatigue. Although less likely, it could be considered in the differential diagnosis, especially if other causes are ruled out.