Management of nonfunctioning pituitary incidentaloma

Prevalence of pituitary incidentaloma is variable: between 1.4% and 27% at autopsy, and between 3.7% and 37% on imaging. Pituitary microincidentalomas (serendipitously discovered adenoma <1cm in diameter) may increase in size, but only 5% exceed 10mm. Pituitary macroincidentalomas (serendipitously discovered adenoma>1cm in diameter) show increased size in 20-24% and 34-40% of cases at respectively 4 and 8years' follow-up. Radiologic differential diagnosis requires MRI centered on the pituitary gland. Initial assessment of nonfunctioning (NF) microincidentaloma is firstly clinical, the endocrinologist looking for signs of hypersecretion (signs of hyperprolactinemia, acromegaly or Cushing's syndrome), followed up by systematic prolactin and IGF-1 assay. Initial assessment of NF macroincidentaloma is clinical, the endocrinologist looking for signs of hormonal hypersecretion or hypopituitarism, followed up by hormonal assay to screen for hypersecretion or hormonal deficiency and by ophthalmologic assessment (visual acuity and visual field) if and only if the lesion is near the optic chiasm (OC). NF microincidentaloma of less than 5mm requires no surveillance; those of≥5mm are not operated on but rather monitored on MRI at 6months and then 2years. Macroincidentaloma remote from the OC is monitored on MRI at 1year, with hormonal exploration (for anterior pituitary deficiency), then every 2years. When macroincidentaloma located near the OC is managed by surveillance rather than surgery, MRI is recommended at 6months, with hormonal and visual exploration, then annual MRI and hormonal and visual assessment every 6months. Surgery is indicated in the following cases: evolutive NF microincidentaloma, NF macroincidentaloma associated with hypopituitarism or showing progression, incidentaloma compressing the OC, possible malignancy, non-compliant patient, pregnancy desired in the short-term, or context at risk of apoplexy.