What symptom suggests a potential issue requiring urgent attention during a breast examination?

Nipple retraction is a significant symptom that can indicate an underlying issue necessitating urgent medical evaluation. This condition can occur due to various reasons, such as an underlying malignancy, infection, or an inflammatory process affecting the breast tissue. Notably, nipple retraction can suggest potential ductal involvement, where breast tissue may be pulling the nipple inward, which could be associated with breast cancer.

Other symptoms listed, such as pendulous breasts, absence of masses, and presence of Montgomery's tubercles, typically do not denote immediate concerns. Pendulous breasts may be a result of genetics or aging but do not suggest malignancy. The absence of masses is generally a reassuring sign during breast examinations. Montgomery's tubercles, which are sebaceous glands located on the areola, are normal anatomical features and their presence is not indicative of disease. Therefore, while all aspects of breast health should be monitored, nipple retraction specifically warrants urgent attention due to its potential association with serious conditions.