What condition is characterized by a slow-growing mandible?

The condition characterized by a slow-growing mandible is hyperpituitarism, which is a result of excessive growth hormone production. In individuals with hyperpituitarism, especially those who have a growth hormone-secreting adenoma, there can be an abnormal elongation of bones, including the mandible, leading to a distinct facial appearance. This excessive growth typically occurs over time, which aligns with the slow growth of the mandible.

Acromegaly, often a result of untreated hyperpituitarism, specifically refers to the physical changes that occur due to chronic excess of growth hormone, including a thicker and elongated mandible. Therefore, while it might seem that acromegaly would also fit the description, hyperpituitarism focuses on the increased hormone production itself, which directly leads to the condition described in the question.

Hypopituitarism and adenomas, in contrast, would not typically result in the slow growth of the mandible. Hypopituitarism refers to insufficient production of pituitary hormones, which would hinder growth, while adenomas are tumors that do not inherently describe the growth characteristics of bone.