Which illness would not be included in the differential diagnosis for a 78-year-old female with chest pain?

Cholecystitis, which is the inflammation of the gallbladder, is primarily associated with abdominal pain and symptoms like nausea, vomiting, and possibly fever. While it can cause referred pain, particularly in the right upper quadrant, it is less commonly the source of chest pain compared to other conditions, especially in the context of an older patient.

In contrast, pneumonia can present with chest pain, especially if there is pleuritic involvement. Congestive heart failure often leads to chest discomfort due to fluid overload or cardiac issues such as myocardial ischemia. Gastroesophageal reflux disease (GERD) is well-known for causing chest pain resembling cardiac pain.

Given these reasons, cholecystitis does not typically manifest as chest pain in the same way that pneumonia, congestive heart failure, or GERD does, making it the least likely to be included in the differential diagnosis for this particular case scenario.