THE unusual association of muscular hypertrophy with childhood hypothyroidism1-8 has been referred to as the Kocher-Debré-Sémélaigne (KDS) syndrome.1 The features of this syndrome include retarded intellectual, physical, osseous, and dental development, constipation, myxedema, bradycardia, a peculiar facies, a large tongue, coarse hair and skin, hypotonia, and prolonged deep tendon reflexes, as in cretinism,9 plus a generalized increase in the skeletal muscle mass, and an athletic, almost herculean, appearance. Descriptions of skeletal muscle pathology in this syndrome are sparse and contradictory.1,3-7
It is the purpose of this paper (1) to report the results of morphological, histochemical, and ultrastructural studies performed on muscle biopsies obtained from two hypothyroid children, one with muscular hypertrophy, as in the KDS syndrome, and one with normal muscular development, (2) to compare these results with previously published data, and (3) to attempt to relate them to some of the known biological effects