Cerumen Impaction: This is often the most common cause of irritation in the external auditory canal, resulting from excessive earwax that can cause discomfort, itching, and sometimes hearing loss. The likelihood of cerumen impaction is high due to the prevalence of earwax issues in the general population.

Otitis Externa (Swimmer's Ear): An infection of the external auditory canal, often caused by bacterial or fungal pathogens, which can lead to itching, redness, swelling, and discharge. This condition is common, especially in individuals who frequently expose their ears to water.
Eczema/Dermatitis: Skin conditions like eczema or dermatitis can affect the external auditory canal, causing irritation, itching, and sometimes a rash. These conditions are relatively common and can be triggered by various factors, including allergies or irritants.
Allergic Reactions: Allergic reactions to ear drops, hearing aids, or other products used in or around the ear can cause irritation and itching in the external auditory canal. With the variety of products used in ear care, allergic reactions are a plausible cause.

Malignant Otitis Externa: A severe infection that can spread to the skull base, more commonly seen in diabetic or immunocompromised patients. Although less common, it is critical to identify due to its potential for serious complications and high morbidity.
Necrotizing Otitis Externa: A rare but serious condition that can lead to significant tissue damage and is often seen in patients with compromised immune systems. Early detection is crucial to prevent severe outcomes.
Relapsing Polychondritis: An autoimmune disorder that can affect the cartilage of the ear, among other areas, leading to inflammation and potential destruction of the cartilaginous structures. Although rare, its potential impact on the patient's quality of life and the ear's structure necessitates consideration.

Keratosis Obturans: A condition characterized by the accumulation of desquamated skin in the external auditory canal, which can cause irritation and potentially lead to hearing loss. It is less common and often associated with other skin conditions.
Cholesteatoma: An abnormal skin growth in the middle ear behind the eardrum, which can sometimes extend into the external auditory canal, causing irritation and other symptoms. While more commonly associated with the middle ear, its extension into the external canal is a rare but significant consideration.