Pituitary pseudotumor (pituitary thyrotroph hyperplasia) caused by unrecognized and untreated hypothyroidism has been described as a rare condition, mostly in adults. There are only a few reports on this condition in children. Here we describe an unusual association of pituitary pseudotumor with hypothyroidism, vaginal bleeding, and growth retardation in a girl at an early stage of puberty. Hormonal testing showed low thyroxine and high TSH levels, hyperprolactinemia, low growth hormone levels and prepubertal levels of gonadotrophins. Ovarian cyst was detected by ultrasound. A large intrasellar mass expanding beyond the sella turcica was detected on MRI. Homogeneous contrast enhancement confirmed pituitary hyperplasia. Therapy with L-thyroxine resulted in rapid improvement of the clinical signs, normalization of the hormone levels, and resolution of the pituitary hyperplasia on MRI within 40 days. In children, prolonged unrecognized primary hypothyroidism might be accompanied by growth deficiency and pubertal disharmony. Pituitary hyperplasia should be sought in these cases. KEY WORDSpituitary pseudotumor, primary hypothyroidism, hyperprolactinemia, ovarian cyst