Follicle abnormalities were identified on the apparently healthy skin of women with acne, in a study that used confocal microscopy to evaluate skin structures in adult women with acne.

The finding was seen in women with both types of acne – diffuse and mandibular – and in patients with both inflammatory and hyperkeratinization features, wrote Louise M. Guenot, MD, of the dermatology department at CHU Nantes, France, and her coauthors. In the women with mandibular acne, there were significantly more follicle abnormalities on the mandibular area of the face, compared with the forehead area, with no acne lesions.

Mandibular acne on a woman's face Obencem/Thinkstock
The study, published online in the International Journal of Dermatology, used reflectance confocal microscopy to evaluate structural differences in women aged 20 and older with mild to severe acne, which had not been done before, according to the authors. The women were prospectively selected during an acne consultation at Nantes University Hospital.

The investigators evaluated two groups of women: 15 women with diffuse acne lesions across the forehead, cheeks, and chin (mean age 38 years) and 15 women with mandibular acne only (mean age 31 years). Skin that appeared to be acne free among those in the diffuse acne group was compared with the skin of a control group of six women with no acne history. In the mandibular acne group, patients served as their own controls: Healthy forehead skin was compared with mandibular skin. In the diffuse acne group, 791 forehead follicles were evaluated, and in the mandibular group, 569 mandible follicles and 475 forehead follicles were evaluated.

The investigators studied several features, including diameter of the infundibulum, thickness of the border, onion-like appearance, keratin plugs, signs of inflammation, vascularization, and presence of Demodex mites.

In the diffuse acne group, infundibulum was larger, compared with controls (94.9 mcm vs. 74.9 mcm; P = .047). The follicle border was thicker, was more hyperkeratinized, and had more keratin plugs in the infundibulum compared with controls, all statistically significant differences. Signs of inflammation, vascularization, and the presence of Demodex mites did not differ significantly between those with acne and controls.

In the mandibular acne group, where each patient served as her own control, follicles in the mandibular area were larger than those on the forehead (99 mcm vs. 91 mcm, P = .03), and the follicle border in the mandibular area was significantly thicker, with an “onion-like hyperkeratinized appearance” that was significantly more common in the mandibular area. In addition, images showed a keratin plug in the infundibulum was present more often in the follicles in the mandibular area compared with the forehead (46.7% vs. 36.8%, P = .002). Inflammation and vascularization were also significantly more common in the mandibular area compared with the forehead.

Among controls, though, no differences in infundibulum diameter, follicle thickness, or quantity of keratin plugs were seen on the forehead compared with the mandibular area. There was no more onion-like appearance or keratin plugs on the forehead than in the mandibular area, Dr. Guenot and her coauthors reported. Their findings show that “the follicle morphology on apparently healthy skin of adult women with acne was significantly different from that of follicles on the normal skin of healthy subjects.”

The results also “support the concept that the management of acne with mandibular involvement, even if the main clinical lesions are inflammatory, should take into account the hyperkeratinization process, and the treatment should thus be both comedolytic and anti-inflammatory,” they added.

The authors had no financial disclosures, and there was no funding source.