Differential Diagnosis

The patient presents with a combination of symptoms including headache, runny nose, itchy eyes, swollen lips, and a possible cyst on the upper inner lip. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Allergic Reaction: This is the most likely diagnosis given the combination of symptoms such as runny nose, itchy eyes, and swollen lips, which are common manifestations of an allergic reaction. The presence of a possible cyst could be related to an allergic reaction or an unrelated condition.

• Other Likely Diagnoses

  • Common Cold: Although the cold typically doesn't cause swollen lips or cysts, some of the symptoms like headache and runny nose could be attributed to a viral upper respiratory infection.
  • Sinusitis: This condition could explain the headache and runny nose, and if the sinus infection is severe, it might lead to facial swelling, though it's less likely to cause itchy eyes or a cyst on the lip.
  • Contact Dermatitis: If the patient has come into contact with an irritant, this could cause itchy eyes, swollen lips, and potentially a reaction on the lip that resembles a cyst.

• Do Not Miss Diagnoses

  • Angioedema: This is a severe, potentially life-threatening condition that can cause rapid swelling of the skin and mucous membranes, including the lips. It often occurs in response to an allergen and can be associated with anaphylaxis.
  • Cellulitis or Abscess: Although less likely given the initial symptoms, if the "cyst" on the lip is actually an infected abscess or cellulitis, it requires prompt antibiotic treatment to prevent spread of infection.

• Rare Diagnoses

  • Sjögren's Syndrome: An autoimmune disorder that could cause dry, itchy eyes and potentially other symptoms, though it's less likely to cause acute lip swelling or a cyst.
  • Erythema Multiforme: A skin condition that can cause target lesions and sometimes mucosal involvement, including the lips, though it's rare and usually associated with other distinctive skin findings.
  • Melkersson-Rosenthal Syndrome: A rare neurological disorder characterized by recurrent, often unilateral, facial paralysis or weakness, swelling of the face and lips, and the development of folds and furrows in the tongue (fissured tongue), which might be considered if other symptoms develop over time.