This 70-year-old man had scattered yellow-to-flesh-colored papules on his sun-exposed skin. The clinician submitted it as actinic reticuloid. Colloid milium (adult form) often occurs on the face and upper extremities of elderly white men, as in this case. The colloid material is thought to be degenerated elastic fibers, and stains with immunohistochemical markers for amyloid P. It is benign. The histology in this case is typical. The differential diagnosis would include other forms of amyloidosis.
At higher power of the same lesion, the deposits are acellular, pinkish gray, and amorphous. The deposits are intimately associated with elastic fibers. Bland fibroblasts form a network around the material.