S4C25P17-1: Colloid milium is a “hyalinosis” of the dermis. The material accumulates in the upper portion of the dermis. As the deposits enlarge, they tend to press upon the epidermis. The horizontal fissuring of the material is a regular artefact; it probably is related to the processing and sectioning of the tissue. Colloid milium may occur in childhood in the absence of significant solar damage to the dermis. In adults, the material has an affinity for zones of solar elastosis. There is some controversy regarding histiochemical characteristics of the “colloid,” but it is PAS+ and, in well-controlled stains, is congo red negative. It is not positive with stains for elastica. In contrast, nodular elastosis shows a positive reaction with elastic tissue stains.