Rare case of central congenital hypothyroidism due to a TSH mutation presenting with macro-orchidism

A male infant was brought to our paediatric endocrine unit with typical clinical features of congenital hypothyroidism (CH) and striking macro-orchidism. On evaluation, free T3, free T4 and thyroid stimulating hormone (TSH) were found to be low, suggestive of congenital CH. Cortisol was within reference range and prolactin was mildly elevated. No suspicious lesions were encountered on neurosonography. On commencing treatment with thyroxine, clinical features of hypothyroidism showed dramatic improvement with regression of testicular enlargement. Genetic analysis revealed deletion of the TSH beta gene.Our case highlights a rare presentation of central CH with macro-orchidism in a genetically proven deletion of TSH beta gene. Macro-orchidism has been widely reported in IGSF-1 mutations leading to central CH; however, central CH and macro-orchidism have not been reported in association with TSH beta deletions.