Mirror-Image Identical Twins Presenting in Mirror-Image Hip Cysts: A Case Report and Review of the Literature

Abstract

One-third of twins are monozygotic. Of monozygotic twins, 25% of them are mirror images. Mirror-imaging occurs when pathologic conditions are present on opposite sides of the body. This is the first case report of mirror-image identical twins with opposite hip pain that were found to have small cysts of the femoral head on opposite hips.Case presentation: 38 year-old mirror-image Asian female identical twins presented with hip pain on opposite sides. MRI demonstrated a 4 mm cyst of the anterior aspect of the left hip, the femoral head and neck junction, with a herniation pit on opposite sides. The right-handed twin had the cyst on the right hip, and the left-handed twin had the cyst on the left hip. Conclusion:Mirror-image pathology in mirror-image monozygotic twins suggests possible cytogenetic factors involved in the etiology of various medical problems. If an identical twin presents with a medical problem, it may be recommended to perform a medical diagnostic work-up on the other twin.