Differential Diagnosis

The patient presents with a combination of symptoms including yellow stool, frontal headache, diarrhea, cervical lymphadenopathy, and nausea, lasting two weeks, with normal CBC and CMP, and a negative tick panel. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis
  • Viral Gastroenteritis: This is a common condition that can cause diarrhea, nausea, and vomiting. The presence of yellow stool could indicate an infection affecting the gastrointestinal tract. The symptoms, along with cervical lymphadenopathy, could suggest a systemic viral infection.
• Other Likely Diagnoses
  • Infectious Mononucleosis (Mono): Caused by Epstein-Barr virus (EBV), it can present with lymphadenopathy, fever, and gastrointestinal symptoms. Although the CBC is normal, some cases might not show the typical atypical lymphocytosis.
  • Food Poisoning: Certain types of food poisoning can cause similar symptoms, including diarrhea, nausea, and vomiting. The yellow stool could be indicative of an infection or toxin affecting the gut.
  • Hepatitis A: Although less common, hepatitis A can present with gastrointestinal symptoms, including diarrhea and nausea, along with lymphadenopathy. The normal CMP does not entirely rule out hepatitis, as liver enzymes can be normal or only slightly elevated in the early stages.
• Do Not Miss Diagnoses
  • Lymphoma: Although rare, lymphoma can present with lymphadenopathy, systemic symptoms like nausea, and less commonly, gastrointestinal symptoms. It's crucial to consider this diagnosis due to its significant implications.
  • Tuberculosis (TB): TB can cause a wide range of symptoms, including lymphadenopathy, gastrointestinal symptoms, and systemic symptoms like fever and headache. It's essential to consider TB, especially if the patient has been exposed or has risk factors.
  • HIV Infection: Acute HIV infection can present with a variety of symptoms, including lymphadenopathy, gastrointestinal symptoms, and systemic symptoms. Given the potential severity of missing this diagnosis, it should be considered.
• Rare Diagnoses
  • Whipple's Disease: A rare, systemic bacterial infection that can cause diarrhea, weight loss, and lymphadenopathy. It's an important consideration in patients with persistent, unexplained symptoms.
  • Celiac Disease: Although primarily known for causing malabsorption and gastrointestinal symptoms, celiac disease can sometimes present with systemic symptoms and lymphadenopathy, especially if there's significant malabsorption or associated conditions.
  • Brucellosis: A zoonotic infection that can cause systemic symptoms, including fever, headache, and lymphadenopathy, along with gastrointestinal symptoms. It's rare but should be considered in individuals with exposure to animals or their products.