Prolactinoma

Snapshot

• A 36-year-old woman presents to the physician with complaint of nipple discharge. She states that she has observed a milky discharge coming from both of her nipples for the past 3 weeks. She notes that other abnormal symptoms she has experienced include intermittent headaches and decreased libido. Physical examination reveals a severe visual field defect, depicted in the image. 

Introduction

• Overview
  • a prolactinoma is a non-cancerous pituitary tumor that overproduces the hormone prolactin
    • treatment is usually with medication to restore a normal prolactin level or surgical resection
• Epidemiology
  • incidence
    • most common pituitary adenoma (40% of all pituitary adenomas)
  • demographics
    • more common in women than men
    • peak prevalence in women ages 25-34 years
  • location
    • pituitary gland
      • lateral parts of anterior pituitary are most common sites
• Pathophysiology
  • prolactinomas arise from monoclonal expansion of pituitary lactotrophs 
    • results in excess synthesis and secretion of prolactin
      • ↑ prolactin inhibits GnRH secretion, leading to ↓ LH and FSH secretion 
• can cause hypopituitarism from mass effect

Presentation

• Symptoms  
  • headache
  • visual changes
    • visual field deficits 
    • blurred vision
    • ↓ visual acuity
  • signs of hyperprolactinemia in women
    • amenorrhea or oligomenorrhea 
    • infertility
    • loss of libido
    • galactorrhea
  • signs of hyperprolactinemia in men
    • loss of libido
    • impotence
    • erectile dysfunction
• Physical exam
  • bilateral hemianopsia 
    • mass lesion disrupts visual pathways crossing in the optic chiasm 
  • galactorrhea
• gynecomastia

Imaging

• MRI or CT scan of the pituitary hypothalamic area 
  • indications
• determine if a mass lesion is present

Studies

• Serum prolactin levels 
  • measure on 1 or more occassions
• Serum pregnancy test
  • rule out pregnancy as the cause of secondary amenorrhea in reproductive-aged females
• Serum TSH
  • rule out the possibility of ↑ prolactin level secondary to an elevated TRH level
• Serum testosterone levels
• measure in men presenting with symptoms of hypogonadism

Treatment

• Medical
  • bromocriptine or cabergoline (dopamine agonists)  
    • indications
      • first-line treatment
        • dopamine suppresses prolactin secretion 
• Surgical
  • surgical resection
    • indications
      • patients who cannot tolerate or do not wish to take dopamine agonists
• patients who do not respond to medical treatment or show progression after an initial response to medical treatment

Complications

• Cranial nerve palsies due to mass effect
• Infertility