Abstract
INTRODUCTION: Langerhans cell histiocytosis (LCH) is a rare disease primarily affecting children. The occurrence of osseous LCH is rare in adults. The lytic lesion of LCH can resemble the lytic lesion of septic or aseptic loosening in an operated case of arthroplasty. CASE REPORT: We report an operated case of total hip arthroplasty whose peri-prosthetic lesion was uncertain by clinical and radiological investigations. Later, a core biopsy revealed the unexpected diagnosis of LCH. CONCLUSION: LCH is an infrequent phenomenon in an adult. This experience taught us the importance of core biopsy and phenotyping in patients with doubtful cystic-lytic lesions over the bone adjacent to the prosthesis.