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In this highly informative case-based session, Prof. Ana Maria Martins presents the diagnostic journey of a male patient with attenuated MPS I, using it as a platform to explore the challenges of identifying endocrine presentations of mucopolysaccharidoses (MPS), particularly short stature. Drawing from published case reports and clinical experience, she highlights how MPS may go unrecognized for years, despite clear warning signs.
The session opens with a brief overview of MPS I and its phenotypic spectrum—from severe Hurler syndrome to attenuated Scheie syndrome. Prof. Martins stresses that enzyme deficiency severity determines the age of onset and disease progression. Attenuated forms can present much later, and often with subtle features, making early diagnosis more difficult.
The featured case involves a boy with frequent otitis media from three months of age, multiple ENT surgeries, recurrent respiratory infections, and hip pain by age five—diagnosed as bilateral Legg-Calvé-Perthes disease. Despite persistent short stature and joint symptoms, he was treated for years with hormone therapy by an endocrinologist, without a metabolic diagnosis. MPS was only suspected at age 18 after referral from a pulmonologist familiar with lysosomal diseases.
Upon metabolic assessment, he was found to have moderate joint contractures, mild facial coarsening, scoliosis, hernias, hepatosplenomegaly, and a heart murmur. Enzyme testing confirmed MPS I. ERT was initiated, resulting in improved joint mobility, reduced abdominal volume, and greater physical stamina.
Prof. Martins uses this case to illustrate several key diagnostic delays and missed opportunities. She emphasizes that pediatric endocrinologists are often the first to monitor bone development through hand and wrist X-rays—making them ideally positioned to spot characteristic signs such as bullet-shaped phalanges.
She also presents a retrospective analysis of early symptoms in attenuated MPS I: short stature, joint stiffness, claw hand deformities, ENT issues, hernias, and cardiac murmurs are all common. A second case of a woman misdiagnosed with rheumatoid arthritis for decades underscores the dangers of diagnostic inertia and the importance of thinking outside traditional specialty “boxes.”
The webinar closes with an algorithm for screening children with short stature and additional features that may point to MPS. Prof. Martins urges all pediatricians—not just endocrinologists—to maintain awareness of MPS in their differential diagnoses, as early treatment significantly improves outcomes in attenuated forms.