A rare case of anterior inferior iliac spine osteochondroma causing external snapping hip syndrome: a case report.

INTRODUCTION AND IMPORTANCE: Osteochondroma is the most common benign bone tumor; however, involvement of the anterior inferior iliac spine (AIIS) is rare. Such lesions may lead to mechanical symptoms due to impingement on surrounding soft tissues, resulting in unusual presentations such as snapping hip syndrome. PRESENTATION OF THE CASE: A 20-year-old male presented with a 3-year history of painful external snapping over the left hip, aggravated by movement. Physical examination revealed a firm, non-tender swelling in the left anterior groin region. Radiographs and CT imaging demonstrated a sessile bony lesion arising from the left AIIS, consistent with osteochondroma. The lesion was excised via an anterior Smith-Petersen approach. Histopathology confirmed osteochondroma. Postoperatively, the patient had complete resolution of symptoms and returned to full activity without recurrence at 1-year follow-up. CLINICAL DISCUSSION: An AIIS osteochondroma is an extremely rare cause of external snapping hip syndrome. The condition results from mechanical irritation of the rectus femoris due to a bony prominence at its origin. CT imaging is essential for diagnosis, while complete surgical excision remains curative with excellent functional outcomes. CONCLUSION: An AIIS osteochondroma should be considered in the differential diagnosis of snapping hip syndrome. Early recognition and surgical excision result in complete symptom resolution and a low risk of recurrence.