Differential Diagnosis for Chronic Cough
Single Most Likely Diagnosis
- Gastroesophageal Reflux Disease (GERD): Despite the patient's denial of acid reflux and epigastric pain, GERD can present atypically, especially with respiratory symptoms like chronic cough. The cough's exacerbation when lying down and improvement when sitting up support this diagnosis, as gravity can worsen reflux when supine.
Other Likely Diagnoses
- Asthma: The chronic cough, provoked by cold air and laughing, could suggest asthma, especially if the patient has other symptoms like wheezing or shortness of breath, which are not mentioned but should be investigated.
- Chronic Bronchitis: A dry, irritating cough, especially in a smoker or someone with significant exposure to pollutants, could indicate chronic bronchitis. However, the absence of sputum production and specific mention of a "tickle" in the throat makes this less likely.
- Allergic Rhinitis: Although the patient denies postnasal drip, allergic rhinitis could still be a cause, especially if the patient has other allergic symptoms. The cough could be a result of an allergic reaction, even without noticeable postnasal drip.
Do Not Miss Diagnoses
- Pulmonary Embolism: Although less likely given the chronic nature of the cough and the absence of other symptoms like acute onset dyspnea or chest pain, pulmonary embolism is a critical diagnosis not to miss due to its high mortality rate.
- Lung Cancer: In patients with a significant smoking history or other risk factors, lung cancer could present with a chronic cough. It's essential to consider this, especially if other symptoms like weight loss, hemoptysis, or persistent chest pain are present, though not mentioned in this case.
- Tuberculosis (TB): TB can cause a chronic cough, and although less common in some regions, it's crucial to consider, especially in patients with risk factors like immunocompromised status or recent travel to endemic areas.
Rare Diagnoses
- Habit Cough: A psychological condition where the cough is a habituated response, often seen in children but can occur in adults. The description of the cough being provoked by laughing and the absence of other symptoms could suggest this, though it's less likely.
- Foreign Body Aspiration: Although more common in children, adults can also aspirate foreign bodies, leading to a chronic cough. The history of coughing fits and vomiting might suggest this, but the chronic nature and specific triggers make it less likely.
- Eosinophilic Esophagitis: An inflammatory condition of the esophagus that can cause chronic cough among other symptoms. It's a rare condition but should be considered in patients with atypical presentations of GERD or those who do not respond to standard GERD treatment.