Which condition is most suspected in a febrile adolescent with severe right lower quadrant pain?

In a febrile adolescent presenting with severe right lower quadrant pain, appendiceal abscess is the most suspected condition due to the common association between appendicitis and abscess formation. Appendicitis is a prevalent condition in this demographic, particularly in adolescents, and can lead to complications such as perforation or the development of an abscess if not treated promptly. The fever indicates an infectious process, which aligns well with appendicitis.

An appendiceal abscess occurs when the infection from appendicitis spreads to surrounding tissues, leading to localized pus accumulation. The severity of right lower quadrant pain often correlates with the progression of appendicitis to an abscess, making this option the most probable diagnosis in the context provided.

Other conditions listed, such as ileus, mucocele, and diverticular abscess, can also cause abdominal pain but are less commonly associated with fever in adolescents or are not as characteristic of the right lower quadrant pain seen in appendiceal issues. For example, ileus typically presents with generalized abdominal discomfort and distension rather than localized pain; mucocele is rare and generally causes non-specific symptoms; diverticular abscess is more common in older adults and less likely in a young adolescent demographic.