In a recent paper Bluefarb1 called attention to the development of a ring of comedos around the scar of a facial epithelioma treated with roentgen radiations.
The ring of comedos is located in the area of clinically nonepitheliomatous skin surrounding the epithelioma and included in or bordering the irradiated area.
Where the neoplasm and the treatment have replaced normal skin and appendages with scar tissue, there are no comedos, of course. The surrounding clinically normal skin which was subject only to the roentgen irradiation shows a different sequela, viz., a partial cicatricial change. The result of this partial cicatrization is a slight change in the structure of the pilosebaceous apparatus, more intense on the surface than below. The result of this epidermal process is a stricture of the sebaceous glands' outlets, a resulting blockade of the outlets and a formation of a comedo in the usual manner.
RONCHESE F. CICATRICIAL COMEDOS AND MILIA. Arch Derm Syphilol. 1950;61(3):498–500. doi:10.1001/archderm.1950.01530100142025
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