Small yellowish-white lesions located between the retinal pigment epithelium and Bruch's membrane are known as:

Small yellowish-white lesions found between the retinal pigment epithelium and Bruch's membrane are referred to as drusen. These structures are commonly associated with age-related macular degeneration and can indicate early changes in the ocular environment. Drusen are composed of lipids, proteins, and other cellular debris and are often used as a marker to assess the risk of progression to more serious conditions affecting vision. Their presence can be indicative of underlying disruptions in retinal health and can impact the function of the retinal layers above them. Understanding the nature and implications of drusen is crucial for diagnosing and managing conditions associated with retinal degeneration.

The other terms presented do not describe the same anatomical features or conditions related to the retinal layers. Detachment refers to the separation of the retina from the underlying tissue, while dermoids are congenital lesions of the skin that can occur in the eye, and dellen are areas of localized degeneration in the cornea due to dryness or pressure from a neighboring lesion. Each of these terms pertains to different aspects of ocular pathology and does not align with the specific description of the lesions in question.