Abstract
Marked degranulation of infiltrating eosinophils both in the epidermis and the dermis in the inflammatory stage of incontinentia pigmenti was observed electronmicroscopically. Adjacent to the degranulation of eosinophils in the dermis, degranulation of mast cells was also apparent and inflammatory processes in such areas were prominent. Since tissues are seriously damaged by eosinophils granules after degranulation, as in the cases of hypereosinophilic syndrome, it is postulated that eosinophilia and resultant infiltration of eosinophils and their degranulation may initiate the inflammatory process of the disease.
