To determine the distinction between a comedo and an infundibular cyst of Favre-Racouchot disease.
A university hospital.
From the 8 patients included in the study, 19 cysts and comedones were evaluated.
Main Outcome Measure:
The distinguishing features between the cysts and comedones of Favre-Racouchot disease.
All lesions were histologically indistinguishable from the primary comedones of acne vulgaris, except for the presence of a marked actinic elastosis in the surrounding dermis. The presence of a variable number of hair shafts and an abundant amount of bacteria, which was positive in the results of Gram staining and periodic acid-Schiff reaction and intermingled with sebum and eosinophilic laminated horny material within the dilated infundibulum, characterizes a comedo and differentiates it from an infundibular cyst.
The cysts and comedones of Favre-Racouchot disease are closed and open comedones. They can be easily differentiated from an infundibular cyst by the histopathologic features rather than by the connection to the surface.Arch Dermatol. 1997;133:743-745
Sánchez-Yus E, Río ED, Simón P, Requena L, Vázquez H. The Histopathology of Closed and Open Comedones of Favre-Racouchot Disease. Arch Dermatol. 1997;133(6):743–745. doi:10.1001/archderm.1997.03890420081009
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