Ectopic Apocrine Glands as a Predisposing Factor for Postinflammatory Medial Meatal Fibrosis

To illuminate pathophysiologic processes in postinflammatory medial meatal fibrosis (PMMF), a rare otologic disease of unknown etiology, which is defined by a progressive, obliterating fibrosis that affects the osseous part of the external auditory canal (EAC) exclusively.Retrospective clinical and histopathologic study.Tertiary referral center.Eleven patients (4 female and 7 male subjects) who underwent surgery of the bony EAC due to PMMF (13 ears operated).Histologic and immunohistochemical assessment of tissue specimens obtained during surgical excision.Detection of ectopic apocrine glands and concomitant inflammatory infiltrate within tissue harvested from the osseous EAC.Additionally to expected histologic findings, such as excessive fibrosis and a chronic inflammatory infiltrate, ectopic spread of apocrine glands was consistently detected in all of our patients.Based on our findings, we suggest that an ectopic occurrence of adnexal structures within the bony EAC may predispose susceptible individuals to the development of PMMF. To avoid postoperative recurrence due to iatrogenic spread of cutaneous adnexal structures during surgery, the split-thickness skin graft should not exceed a thickness of 0.4 mm.