Postnasal Drip Syndrome (PNDS): This condition is characterized by the sensation of mucus running down the back of the throat, often leading to a chronic cough. The cobblestone appearance of the pharynx is due to lymphoid hyperplasia, which can be seen in conditions causing chronic irritation, such as PNDS.

Gastroesophageal Reflux Disease (GERD): GERD can cause chronic cough due to the reflux of stomach acid into the esophagus, irritating the throat and leading to coughing. The cobblestone pharynx could be a secondary finding due to chronic irritation.
Allergic Rhinitis: Similar to PNDS, allergic rhinitis can cause postnasal drip, leading to chronic cough and irritation of the pharynx, resulting in a cobblestone appearance.
Chronic Sinusitis: Infection or inflammation of the sinuses can lead to postnasal drip, cough, and pharyngeal irritation, contributing to the cobblestone appearance.

Laryngopharyngeal Reflux (LPR): A subtype of GERD that specifically affects the laryngopharynx, LPR can cause significant irritation and damage if not treated, leading to chronic cough and changes in the pharynx.
Tuberculosis (TB): Although less common, TB can cause chronic cough and pharyngeal lesions. It's crucial to consider TB, especially in high-risk populations or areas with high TB prevalence, to prevent missing this potentially deadly diagnosis.
Head and Neck Cancer: Though rare, cancers of the head and neck can present with chronic cough and changes in the pharynx. Early detection is critical for effective treatment.

Sarcoidosis: A systemic disease that can affect multiple organs, including the lungs and lymph nodes, sarcoidosis can cause chronic cough and might lead to lymphoid hyperplasia in the pharynx, though this is less common.
Wegener's Granulomatosis (Granulomatosis with Polyangiitis, GPA): A rare autoimmune disorder that can affect the respiratory tract, GPA might present with chronic cough and pharyngeal involvement, though it is much less likely than other diagnoses listed here.