Differential Diagnosis

The patient presents with a complex array of symptoms including constant headaches, night fevers, dry cough with haemoptysis, loose bowel motions, chest pain with coughing, and visual disturbances, among others. Given the breadth of symptoms, the differential diagnosis can be organized into the following categories:

• Single Most Likely Diagnosis
  • Infectious Mononucleosis (Mono): This diagnosis is considered due to the combination of symptoms such as sore throat, fever, fatigue (implied by affecting sleep and work attendance), and the presence of a swollen, erythematous tonsil. The recent onset of symptoms and the fact that household contacts are also unwell support an infectious cause.
• Other Likely Diagnoses
  • Tuberculosis (TB): The presence of night fevers, dry cough, haemoptysis, and chest pain with coughing are classic symptoms of pulmonary TB. The slightly reduced breath sounds bilaterally also support this diagnosis.
  • Influenza or Other Viral Respiratory Infections: Given the flu-like symptoms (fever, cough, sore throat, and body aches), influenza or another viral respiratory infection could be a likely diagnosis, especially with the recent runny nose and the fact that household contacts are also unwell.
  • Pneumonia: The symptoms of fever, dry cough, chest pain with coughing, and slightly reduced breath sounds could indicate pneumonia, especially if caused by a bacterial pathogen.
• Do Not Miss Diagnoses
  • Meningitis: Although the patient does not exhibit the classic triad of fever, headache, and stiff neck, the presence of constant headaches, fever, and visual disturbances (which could be indicative of increased intracranial pressure) necessitate considering meningitis, given its potentially fatal outcome if missed.
  • Lung Cancer: Although rare in a 19-year-old, the presence of haemoptysis and chest pain with coughing, along with systemic symptoms like night fevers and weight loss (not explicitly mentioned but could be implied by loose bowel motions and affecting work attendance), make it crucial not to miss this diagnosis.
  • Sarcoidosis: This condition can present with a wide range of symptoms including respiratory issues (cough, chest pain), systemic symptoms (fever, night sweats), and neurological symptoms, making it a "do not miss" diagnosis due to its potential for serious complications if left untreated.
• Rare Diagnoses
  • Wegener's Granulomatosis (Granulomatosis with Polyangiitis, GPA): This rare autoimmune disorder can cause a variety of symptoms including respiratory issues (cough, haemoptysis), systemic symptoms (fever, night sweats), and renal issues, among others. The combination of haemoptysis, chest pain, and systemic symptoms could suggest this diagnosis, although it is less likely.
  • Lymphoma: Given the systemic nature of the symptoms (fever, night sweats, weight loss implied by loose bowel motions), lymphoma could be considered, especially if other diagnoses are ruled out. However, it is rare in this age group and would be considered a diagnosis of exclusion.