Launois syndrome (acromegalic gigantism) is typically caused by a pituitary tumor that secretes excess growth hormone. This condition results in the enlargement of skeletal and soft tissue, leading to characteristic gigantism and acromegaly.
Launois syndrome (LS), also known as acromegalic gigantism or pituitary gigantism, stems from the excessive production of growth hormone (GH) by the pituitary gland in the context of pituitary adenoma or hyperplasia, which sits in an enlarged sella turcica [1] [2]. At least 50% of LS cases are genetic in origin [3]. LS can occur as a mutation (for example in aryl hydrocarbon receptor interacting protein (AIP) gene), X-linked, familial or sporadic disorder.
There are two main phenotypic changes, namely gigantism, and acromegaly. Acromegaly typically occurs in adulthood, after the closure of the growth plates and sometimes in older children [4]. Gigantism typifies childhood onset of disease, when epiphyseal plates have not closed, leading to excessive growth of bones and thus an abnormally tall stature. Individuals with gigantism may experience less of the typical acromegaly features.
Abnormal growth is mediated by increased secretion of insulin-like growth factor I (IGF-I). Hyperprolactinemia is also common and may present as hypothyroidism, galactorrhea in females, and adrenal insufficiency. The former is associated with larger tumors and earlier onset of disease [5].
Acromegaly is insidious in onset, often occurring over years. In such cases, tumors are slow growing, leading to the average presentation in the fifth decade. Its clinical manifestations are a result of both skeletal and soft tissue growth, and these characteristically entail enlargement of the jaw, lips, nose and internal organs, for example, goiter. Furthermore, there is a growth of feet and hands, excessive sweating, increased body odor, arthropathy, joint stiffness and pain, and osteoarthritis-like features [6] [7].
Symptoms related to the compressive effects of the tumor include headaches, visual disturbances such as bitemporal hemianopsia, and signs of hypopituitarism. The latter happens when tumor proliferation damages the pituitary stalk and interrupts communication between the pituitary gland and the hypothalamus, thereby effectively severing the inhibitory mechanisms.
Additional findings of LS include obstructive sleep apnea, diabetes mellitus, heart disease, dyslipidemia and dysregulation of calcium metabolism and gastrointestinal (colon) malignancies.
Diagnosis of Launois syndrome relies on clinical evaluation and biochemical testing. Because of its slow progression, diagnosis can be made up to 10 years after disease onset. Biochemical parameters that are typically measured include:
Radiography of the skull and limbs is one of the imaging modalities carried out. Both computerized tomography (CT) and magnetic resonance imaging (MRI) scanning are useful in visualizing the tumor, however, MRI is more sensitive.
Screening for possible complications, such as diabetes and cardiovascular disease may involve specific tests such hemoglobin A1c (HbA1c), echocardiography and electrocardiography.