LAUSR

Dear Editors, We report a recent case of a patient affected by hidradenitis suppurativa (HS) whose disease recurred on a surgical scar. A 67-year-old overweight (body mass index: 39) male with a 2-year history of HS (stage III Hurley) complained of two small nodules that recently appeared on his right thigh. The patient was a smoker for 30 years (>10 cigarettes a day), suffering from metabolic syndrome, atrial fibrillation, obstructive pulmonary disease, and chronic renal failure. HS medical history showed repeated unsuccessful courses of oral antibiotics and adalimumab that was started 18 months before our observation. Six weeks before the patient presented to us, he underwent, upon temporary discontinuation of adalimumab for 2 weeks, a wide surgical excision followed by a direct primary suture of an HS painful deep-seated plaque (9 cm × 4 cm) located on the right inner thigh. Reason for surgery was discomfort during deambulation because of chronic friction of the oedematous scrotum with the inner thighs (Figure 1A). Histopathology confirmed the diagnosis of HS, showing multiple cysts with signs of chronic inflammation and suppuration. Surgical margins were free (Figure 1B). On physical evaluation, the patient showed the presence of two inflamed and draining erythematous nodules, 1.5 and 2 cm in diameter, localised to the site of the surgical suture (Figure 1C). On ultrasound evaluation using a highfrequency device (MyLab Touch, Esaote SpA, Genova, Italy, 15-18 MHz), the nodules showed the presence of fluid collections, a finding typical of HS. In our case, HS lesions followed the scarring process and appeared right on the surgical scar, configuring the Koebner phenomenon (KP), which, by definition, indicates the onset of new lesions at the site of skin injury in patients with preexisting dermatoses. Four categories of KP are described: I = true koebnerisation, II = pseudo-koebnerisation,