Hypothyroid Myopathy-A Rare Case from Paediatric Practice.

Hypothyroid myopathy is uncommon in childhood. Severe hypothyroid myopathy observed in paediatric practice is a part of Kocher-Debré-Semelaigne syndrome (KDSS, OR-PHA:2349), a rare disorder characterised by muscular pseudohypertrophy and long-standing moderate-to-severe hypothyroidism. We present a pubertal girl with KDSS diagnosed with severe myopathy and significantly limited mobility and progressively increasing pains in the lumbar area, hip joints, and the lower limbs. Additionally, the patient presented metabolic syndrome with severe obesity, growth retardation, and educational difficulties. In this case, adequate hormone replacement therapy with Levothyroxine evoked full recovery of the myopathy and a significant reversal in the patient's general condition. In conclusion, emphasizing the knowledge related to KDSS can improve the diagnosis and prognosis of the condition.