A Sterile Folliculocentric Acneiform Eruption Mimicking Infection After Hair Transplantation: Clinical Pattern Recognition and a Proposed FUE Epidermal Cap–Angle Mechanism

ABSTRACT Background Acneiform eruption following hair transplantation is frequently encountered in clinical practice but remains incompletely characterized. Because these pustular eruptions may resemble postoperative infection, they often lead to unnecessary antibiotic use. Aims To characterize the clinical pattern of a sterile folliculocentric acneiform eruption after hair transplantation and to propose a hypothesis‐based mechanistic model integrating graft morphology and implantation geometry. Patients/Methods In this retrospective observational cohort study, 76 consecutive patients who developed acneiform eruption were analyzed. Clinical features, eruption timing, anatomic distribution, graft composition, and microbiologic findings were evaluated. Results Mean onset occurred at postoperative day (POD) 3.1 (SD 1.1), with 84% of cases presenting between POD 2–4. Eruptions were predominantly observed in multi‐hair graft areas following FUE procedures and were strictly confined to the transplanted recipient zone. Among 35 affected patients who also received lateral acute‐angle single‐hair grafts, those lateral zones were spared in 91.4% (32/35), an intra‐individual comparison supporting an angle‐dependent pattern. Wound cultures ( n = 8) showed no pathogenic bacterial growth. Lesions were confined to the transplanted recipient area and resolved with conservative management. Conclusions This sterile folliculocentric eruption appears to represent a technique‐associated inflammatory reaction that may mimic infection in the early postoperative period. To our knowledge, this is the first characterization of this discrete, early‐onset sterile entity as distinct from previously described post‐transplant folliculitis, supporting a non‐antibiotic, stewardship‐oriented management approach. The proposed epidermal cap–angle mechanism is presented as a testable hypothesis.