What is the hallmark sign of retinoblastoma?

The hallmark sign of retinoblastoma is the white pupillary reflex, also known as leukocoria. This occurs when light reflects off the tumor in the retina, causing a white appearance in the pupil that is most noticeable when light is shone into the eye, such as in photographs taken with flash. This sign is critical for early detection, as it can alert caregivers and healthcare providers to the potential presence of a retinoblastoma tumor, which requires prompt evaluation and intervention to optimize outcomes.

Strabismus, while it can occur in children with visual impairment, is not specific to retinoblastoma and can result from various other conditions. Prolonged irritation of the eye is a nonspecific symptom that could indicate multiple eye disorders but is not a hallmark sign for retinoblastoma. Retinal detachment may occur in various eye conditions, but it is not characteristic of retinoblastoma and does not serve as a primary identifier for this type of cancer. Thus, leukocoria stands out as the definitive and characteristic manifestation associated with retinoblastoma.