ESPE Abstracts

Background: Pituitary hyperplasia secondary to primary hypothyroidism (PHPH) is a rare cause of sellar mass in paediatric patients. Longstanding and untreated primary hypothyroidism leads to hyperplasia of thyrotrophs and lactotrophs as well as transdifferentiation of somatotrophs to thyrotrophs. Hashimoto's thyroiditis is the most common cause of hypothyroidism in PHPH. Clinical findings of PHPH include growth retardation, obesity and symptoms of hypothyroidism. Neurological signs are rare. TSH levels are usually very high, thyroid hormones are reduced. Prolactin may be increased, GH decreased, while other pituitary hormones are usually unaffected. MRI imaging typically shows an enlarged and homogeneous pituitary gland, but cannot reliably distinguish PHPH from pituitary tumors. Recognizing PHPH and starting treatment with levothyroxine can avoid nonessential surgical interventions.

Clinical Case: We present a case of an ex-premature 12-year-old child affected by fetal alcohol syndrome, mild neurocognitive delay, multiple brain malformations (triventricular hydrocephalus, anomalies of interhemispheric commissures and of visual pathways, enlargement of the pituitary gland) with a history of two spinal surgical operations for occult spinal dysraphism. Two weeks after the last spinal surgery, the patient accessed the Emergency Department of referral hospital reporting headache, nausea, vomiting and lower limb hyposthenia. A CT scan showed further increase in pituitary gland size; blood tests revealed elevated TSH levels (383.8 IU/mL) with reduced fT4 and fT3 levels. Therefore, the patient was transferred to Meyer Children's Hospital IRCCS in Florence for urgent neurosurgical procedure of the pituitary mass. An endocrinological evaluation revealed slowed linear growth and progressive weight gain over the past 3 years with a history of gradual loss of appetite and fatigue over the last 6 months. Severe primary hypothyroidism (TSH 454 IU/mL) was confirmed, anti-thyroid peroxidase antibodies were positive; other pituitary hormones were in range. Thyroid ultrasound was consistent with autoimmune thyroiditis. Low-dose levothyroxine (1 µg/kg/die) was initiated. After a two-week treatment with progressive increase of levothyroxine dosage, patient's symptoms improved, fT3 and fT4 levels normalized and TSH significantly reduced (72 IU/mL). Brain surgery wasn’t carried out, only spinal revision surgery was performed.

Conclusions: We emphasize the necessity to assess pituitary function in all patients with pituitary structure alterations, even in cases of complex syndromes and seemingly stable neuroimaging situations. In these patients, a slowdown in growth, excessive weight gain and fatigue need to be investigated, while evaluating thyroid function. Finally, we underscore that the appropriate diagnosis of PHPH prevents unnecessary surgical interventions.