A 26-year-old female presented to the outpatient department with the main complaint of throbbing headache for the past three years. She experienced weight gain and increase in height for the same duration. She also complained of increased thirst, urination and appetite for the past three months.
Increased level of serum growth hormone (> 40 ng/ml) was noted. Based on the clinical history and lab parameters, imaging of the extremities and MRI of the brain was done. Radiograph of the skull demonstrated increased calvarial thickness with widened sella (Fig 2). Mandible was enlarged and forwardly displaced suggestive of prognathism (Fig 2). Radiograph of bilateral hands showed hypertrophied terminal phalangeal tufts with spade like appearance (Fig 3, 4). Increased soft tissue density was also noted in the hands (Fig 3, 4). Radiograph of the foot showed increased heel pad thickness (Fig 5). MRI of the brain showed T1 iso, T2 high signal intensity lesion extending in the sellar and suprasellar region (Fig 6, 7, 8). Indentation was noted at the level of the diaphragma sellae giving rise to snowman sign (Fig 7). The lesion abutted the internal carotid arteries bilaterally; however, no encasement of the arteries was noted (Fig 8).
Growth hormone cell adenomas cause gigantism in children and acromegaly in adults . The most common cause of acromegaly in adults is pituitary adenoma. Pituitary adenomas are adenohypophysial tumours composed of secretory cells that produce pituitary hormones . Patients present with enlarged bones of hands, feet and jaw. Patients may also present with enlarged tongue and visceral organs dysfunction. Secondary diabetes mellitus is often noted in these patients. Pituitary adenomas, owing to their mass effect, can also present with bitemporal hemianopia, features of hypopituitarism and headache.
Plain radiograph of skull in acromegaly demonstrates calvarial thickening, frontal bossing, enlarged paranasal sinuses and enlarged sella turcica. The mandible also enlarges resulting in prognathism and increased gaps between the teeth. Vertebral fractures without loss of bone mineral density are related to increased bone turnover in acromegaly. Terminal phalangeal tufts become hypertrophied and have a "spade like appearance", giving rise to spade phalanx sign. Heel pad thickness may be increased (>25 mm in male and >23 mm in female). Pituitary adenomas, as the cause, appear as sellar or combined intra- and suprasellar mass that cannot be identified separately from the pituitary gland. CT may show an enlarged, remodeled sella turcica with intact lamina dura. Macroadenomas are usually isodense with gray matter. Cysts (15-20%) and hemorrhage (10%) are common but calcification is rare (less than 2%). Macroadenomas are usually isointense with cortex on T2 weighted images but can also demonstrate heterogeneous signal intensity. The posterior pituitary "bright spot" is absent (20%) or displaced into the supradiaphragmatic cistern (80%) on T1-weighted sagittal scans. Hyperintensity may be seen along the optic pathways on T2/FLAIR images in 15-20% of cases in which macroadenomas compress the optic chiasm. Hemorrhagic adenomas "bloom" on T2*. Most macroadenomas enhance strongly but heterogeneously on contrast-enhanced T1 images .
The treatment of choice in cases of acromegaly secondary to pituitary macroadenoma is resection of the secreting adenoma . Surgery is often followed by radiation therapy. Radiation therapy results in 50% reduction in growth hormone levels within two years. Medical treatment is used after surgery to suppress growth hormone secretion, for which drugs like octreotide and somatostatin are used.
Take Home Message:
In patients with progressive growth of the extremities associated with increase bulk of the soft tissues, acromegaly should always be considered as a differential diagnosis. Pituitary macroadenoma is the most common cause of acromegaly in an adult. Careful imaging evaluation of these patients may not only help in early diagnosis and treatment but can also prevent the complications associated with the disease.
Written informed patient consent for publication has been obtained.
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