Signs and Symptoms of Tumor Progression

In the past, doctors looked for a very specific “triad” of symptoms to diagnose Nelson syndrome: skin darkening, a visible tumor on an X-ray, and extremely high levels of the hormone ACTH ^[1][2].

Today, our tools are much more sensitive. We now know that the vast majority of patients—about 68% in one specific study cohort—have no symptoms at all when their tumor first shows signs of growth on a modern MRI ^[3]. Because tumor progression often happens silently, your care team focuses on regular imaging rather than waiting for physical changes to appear ^[4]. When symptoms do occur, they usually fall into two categories: skin changes and vision changes.

The Mechanism of Skin Darkening

The most classic sign of this condition is hyperpigmentation, a deep darkening of the skin ^[1]. This is not a standard tan caused by the sun; it is a chemical reaction occurring from the inside out. Remember that ACTH is often very high after adrenalectomy because cortisol feedback is absent, so pigmentation is a clue rather than a definitive test for growth.

• The Hormone Link: When your pituitary tumor grows, it produces high amounts of ACTH (adrenocorticotropic hormone) ^[2].
• The “Cross-Talk”: High levels of ACTH can “cross-talk” with the receptors on your skin cells (melanocytes) that are normally triggered by sun exposure ^[5][6]. This tells your skin to produce more pigment even if you haven’t been outside.
• Where to Look: This darkening often appears first in areas that are already prone to pigment, such as:
  • Surgical scars or recent injuries ^[7].
  • The creases of your palms and knuckles.
  • The inside of your mouth, particularly the gums.
  • Areas of friction, such as under your arms or around your waistline.

Research shows that when the tumor is successfully treated and ACTH levels fall, this skin darkening often fades or resolves completely ^[1][7].

How Growth Affects Your Vision

Your pituitary gland sits in a small bony space at the base of your brain. Directly above it lies the optic chiasm—the “junction box” where the nerves from your left and right eyes cross over each other ^[8].

Because space is limited, even a small amount of tumor growth in an upward direction (suprasellar extension) can put physical pressure on these delicate nerves ^[8][9].

• Bitemporal Hemianopsia: This is the most common visual defect ^[10]. Because the tumor presses on the middle of the “junction box,” it affects the nerve fibers responsible for your side vision. You may feel like you are wearing “blinders” or have lost your peripheral vision, even if you can still see clearly straight ahead ^[11].
• Acuity and Clarity: If the pressure continues, you may notice a decrease in visual acuity (how sharp your vision is) or find that colors look “washed out” or less vibrant ^[10][12].
• Silent Compression: Importantly, about 36% of patients in one study who had tumor pressure on their optic nerves on an MRI did not actually have any detectable vision loss yet ^[10]. This is why formal vision testing (visual fields) is a standard part of your long-term follow-up.

Why We Monitor “Silent” Growth

In a study of patients with tumor progression, only 9% presented with the classic triad of symptoms ^[3]. Another 23% had skin darkening but still had perfect vision ^[3].

Waiting for symptoms like vision loss to appear can be dangerous because the pressure on the optic nerves can sometimes cause lasting damage if left too long ^[9]. Regular MRIs and blood tests allow your doctors to identify CTP-BADX (Corticotroph Tumor Progression) while it is still “silent,” giving you the opportunity to discuss treatment options before your quality of life is affected.

For information on what to do if you notice sudden, severe changes in your vision or health, please refer to the monitoring and emergency guidelines in the following sections. Sudden vision loss, severe headache, double vision, eyelid drooping, nausea/vomiting, or confusion requires emergency assessment.