Laboratory Studies
The clinical findings of multiple open and closed comedones with yellowish nodules of elastotic material in a middle-aged to elderly individual with actinic damage are sufficient to establish the diagnosis.
Histologic Findings
Significant actinic elastosis and epidermal atrophy are usually seen. Comedones similar to those of acne vulgaris are seen. Although the disorder has been described as containing cysts, many of the apparent cysts really are nodules of elastotic material. [14] Gram-positive bacteria that stain periodic acid-Schiff positive have been noted. [15] The comedones are likely colonized with Propionibacterium acnes, Corynebacterium acnes, Staphylococcus albus, and Malassezia yeasts. Hair shafts may or may not be found within the comedones.
See the image below.
Multiple comedones, dilated and plugged follicular infundibula, and epidermal cyst formation. Courtesy of DermNet New Zealand and Pathlab Bay of Plenty (https://www.dermnetnz.org/assets/Uploads/pathology/t/figure2favrerac.jpg).
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Multiple comedones, dilated and plugged follicular infundibula, and epidermal cyst formation. Courtesy of DermNet New Zealand and Pathlab Bay of Plenty (https://www.dermnetnz.org/assets/Uploads/pathology/t/figure2favrerac.jpg).
