Acromegaly

Acromegaly is the result of excessive growth hormone (GH) production, most commonly from an adenoma of the pituitary.

It most commonly affects adults in middle age and can result in severe disfigurement, serious complicating conditions, and premature death. It has both an insidious onset and slow progression and may be difficult to diagnose in the early stages, only being diagnosed when the external features, especially of the face, become noticeable.

Clinical presentation

• soft tissue swelling visibly resulting in enlargement of the hands, feet, nose, lips and ears, and a general thickening of the skin
• soft tissue swelling of internal organs, notably the heart with attendant weakening of its muscularity, and the kidneys, also the vocal cords resulting in a characteristic thick, deep voice and slowing of speech
• generalised expansion of the skull at the fontanelle
• pronounced brow protrusion, often with ocular distension
• pronounced prognathism with attendant macroglossia and gaping teeth
• hypertrichosis, hyperpigmentation, and hyperhidrosis may occur in these patients

Pathology

Over 90% of cases are the result of a pituitary macroadenoma. Expansion into the sella turcica may result in compression of surrounding structures, most importantly, the optic chiasm. The majority of pituitary tumours are incidental and do not have a genetic component.

The remaining 10% of cases are the result of other tumours of the pancreas, lungs or adrenal glands that release GH. A very small number of cases result from the excessive use of exogenous GH in atheletes.

Radiographic features

Plain film

Skull

Calvarial thickening, enlarged sinuses and an enlarged sella turcica. Prognathic jaw.

Hands

Terminal phalangeal tufts become hypertrophied and have a "spade appearance". Joint spaces may be minimally enlarged. Premature osteoarthritis can set in the advanced stages of acromegaly.

Feet 

Heel pad thickness may be increased

MRI Pituitary 

Enlarged pituitary with uptake of gadolinium. The MR diagnosis of a pituitary macroadenoma is relatively straightforward. Dynamic contrast enhanced MR increases the sensitivity to detect microadenomas. Microadenomas are hypoenhancing as compared to the normal pituitary gland.

Complications

• severe headache
• arthritis and carpal tunnel syndrome
• cardiomegaly
• hypertension
• diabetes mellitus
• heart failure
• renal failure
• optic chiasm compression leading to visual field loss (typically bitemporal hemianopia)
• increased palmar sweating and seborrhea are clinical indicators of active growth hormone (GH) producing pituitary tumours

Etymology

The word acromegaly is derived from the Greek words akros "extremities" and megalos "large"