Bilateral Perthes Masking Morquio Disease

INTRODUCTION: Perthes disease radiography can mask other diseases. Properly observing the X-ray and changes in other joints helps to discard Perthes-like conditions. Association with changes in other systems, as well as the pathological history and even the examination of family members can help diagnose early attenuated cases of rare diseases. CASE PRESENTATION: The case of a girl with hip pain, limp and doubtful radiographs is presented. Perthes disease was diagnosed elsewhere and physical therapy and analgesics were prescribed. As a second opinion, family look for another orthopedic physician, who looks beyond hip pain and limp. Full body X-rays are suggestive of skeletal dysplasia. Metabolic disease diagnosis is suspected with pathological history of the younger brother, with repetitive respiratory infections, as well as abnormal X-ray panel. Multiple dysostoses in both patients are demonstrated. The above findings help to diagnose Morquio disease in an attenuated variant after molecular examinations. CONCLUSION: Early diagnosis in progressive diseases is essential to avoid progression to multi-organ deterioration. It is important that physician become familiar with habitual characteristics of Perthes disease on the pelvis radiograph, in order to unsure the error in the diagnosis.