Pituitary Hyperplasia Due to Primary Hypothyroidism – Apropos of 2 Cases

Nicolescu Corina Ramona; Lucie Bazus

Introduction: In pediatric age range pituitary hyperplasia (PH) defines a reversible enlargement due to increase in the number in one or more hormone-producing cell types. It can occur as a normal response to physiological stimulation (puberty, pregnancy) or as a pathological condition. PH secondary to primary hypothyroidism (PHT) is a common finding. Long-standing severe PHT induces PH via thyrotropin-releasing hormone (TRH).

Case presentation: We present two children with severe PHT, Van Vyk-Grumbach syndrome (VWGS), and reversible PH. They were treated with thyroxine replacement therapy with favorable clinical, biological, and radiological outcomes (table 1).

Table 1 – Clinical, biochemical, and radiological findings of the patients
	Clinical	Biochemistry	Ultrasonography (US) Bone age	Brain MRI	Treatment	MRI follow-up (6 months after diagnosis)
Patient 110- year-old boy	Growth velocity 0 cm/24 months Weight 31 kg (25^th P) Height 126 cm (<3^rd P) HR 66/min Hypothyroid phenotype	TSH 2400 mIU/L fT4 1 pmol/L Thyroglobuline 21 μg/L Positive anti-TG and anti-TPO antibodies FSH 6.4 IU/L LH < 0.3 IU/L Prolactin 2045 mIU/L	Thyroid - normally sized gland with alterations of echogenicity and homogeneity of the parenchyma Bone age 6 years	PH 18 × 12 × 17 mm, convex upper margin	L-T4	Pituitary height 9 mm
Patient 26-year- old girl	18-month history of growth arrest Weight 18 kg (25^th P) Weight 102 cm (< 3^rd P) HR 64/min Hypothyroid phenotype	Hb 8.4 g/dL Creatinine 63 μmol/L TSH 2200 mIU/L fT4 1.1 pmol/L Thyroglobuline 63 μg/L Positive anti-TG and anti-TPO antibodies FSH 6.4 IU/L LH < 0.3 IU/L Estradiol 12 ng/L Prolactin 2127 mIU/L	Moderate goiter with heterogeneous structure Bone age 3 years Pelvic US – normal uterus and ovaries	PH 14 × 10 × 6 mm, convex upper margin, no contact with the optic chiasm	L-T4	Pituitary diameter 4 mm

Conclusion: In PHT PH is secondary to diffuse enlargement of the anterior pituitary lobe caused by the loss of negative feedback, with increased hypothalamic TRH secretion accompanied by thyrotrophic, and sometimes lactotrophic hyperplasia. PH is mainly asymptomatic and has several MRI morphology characteristics (symmetrically enlarged pituitary, convex upper border, suprasellar extension, variable compression of the optic chiasm). The treatment of PHT results in resolution of the PH and unnecessary neuro-surgical intervention is spared. Pediatricians should be aware of the PHT-induced pituitary enlargement and this common entity should not be confused with pituitary adenoma.

ESPE Abstracts

P3-195