Which of the following conditions does NOT involve hormonal imbalance?

Meningioma is a type of tumor that develops from the meninges, the protective membranes covering the brain and spinal cord. Unlike the other conditions listed, meningiomas are not primarily associated with hormonal imbalances. Instead, they are typically classified as central nervous system tumors and their progression and symptoms result from direct pressure on surrounding neural structures rather than hormonal alterations within the body.

In contrast, conditions such as thyrotoxicosis involve excessive thyroid hormone production, resulting in various systemic effects due to hormonal dysregulation. Adrenomegaly refers to the enlargement of the adrenal glands, which can be linked to altered hormone production or regulation. Melasma, while primarily a skin condition characterized by hyperpigmentation, is often associated with hormonal changes, particularly in relation to pregnancy or contraceptive use.

Understanding the underlying nature of these conditions is crucial for differentiating them based on whether they directly involve hormonal imbalances or not, further emphasizing why meningioma stands out in this context.