Examination of hematoxylin-eosin–stained sections demonstrated mineralization within the dermis and within dilated follicular infundibulae, appearing as basophilic fine granules and larger deposits of material consistent with calcium. Larger deposits evoked a foreign body–type giant cell reaction. The overlying epidermis showed irregular acanthosis with areas of extensive pseudoepitheliomatous hyperplasia. Focally, the hyperplastic epithelium partially surrounded subjacent dermal calcium deposits. There were areas of transepidermal elimination of calcium, with extrusion through both intraepidermal channels as well as follicular ostia.
Perforating Papules in Chronic Renal Failure. Arch Dermatol. 1998;134(1):97-102. doi: