Lymph node involvement in axillary hidradenitis suppurativa: A clinical, ultrasonographic and bacteriological study conducted during radical surgery

Background: Hidradenitis suppurativa (HS) is an inflammatory and chronic-recurrent disease of the hair follicle. Its aetiopathogenesis is not completely known. Although bacterial colonization and superinfection are clinically relevant, lymph node involvement has rarely been studied. Objectives: In this pilot retrospective study, we evaluated the clinical and microbiological nodal involvement in patients with axillary hidradenitis suppurativa. Materials and methods: We retrospectively analyzed patients suffering from axillary hidradenitis suppurativa and referred to the Dermatology Unit of the Foundation Ca’ Granda Ospedale Maggiore Policlinico in Milan between October 2018 and November 2019. The sampling procedure took place during the surgical excision of lesions at the Operative Unit of Plastic and Reconstructive Surgery of Policlinico San Donato Hospital. Three types of sample were sent to microbiological analysis: exudate swab, axillary lymph node, fistula. Result: In total, we recruited 10 patients. Two of them underwent bilateral axillary surgery. Nine lymph nodes were analyzed. In one patient, bacterial culture in lymph nodes, skin lesions and fistulae matched. Conclusions: Unequivocable conclusions cannot be drawn due to the low number of patients. Further studies are necessary to confirm the preliminary results of our retrospective pilot study.