All of the following are featured by dermal hyperpigmentation except:

Correct Answer: A

Rationale: Dermal hyperpigmentation, also known as hyperpigmentation of the skin, is commonly associated with conditions such as Addison's disease, hemochromatosis, and bronchogenic carcinoma. In Addison's disease, there is increased production of melanin due to elevated levels of adrenocorticotropic hormone (ACTH) which stimulates melanocytes. Hemochromatosis can cause hyperpigmentation due to excess iron deposits in the skin. Bronchogenic carcinoma can lead to a condition known as acanthosis nigricans, characterized by dark, velvety discoloration of the skin primarily around the neck and armpits. However, Conn's syndrome, which is a primary aldosteronism resulting from an adrenal adenoma or hyperplasia, is not typically associated with dermal hyperpigmentation.

Correct Answer: A

Rationale: Phaeochromocytoma is a neuroendocrine tumor that arises from the chromaffin cells of the adrenal medulla. It is the most common cause of a catecholamine-secreting tumor in adults. While it can also rarely occur outside the adrenal gland (referred to as extra-adrenal or paraganglioma), the majority of cases originate within the adrenal medulla. Symptoms of phaeochromocytoma are due to the excessive release of catecholamines (epinephrine and norepinephrine), leading to a characteristic triad of headaches, sweating, and palpitations. Therefore, the commonest cause of phaeochromocytoma is a tumor of the adrenal medulla.

Correct Answer: C

Rationale: In Cushing's syndrome, the adrenal glands produce an excess amount of cortisol over an extended period. The correct answer is C) Sexual precocity. This option is not typically associated with Cushing's syndrome. Here's why the other options are incorrect: A) Psychosis: Patients with Cushing's syndrome can experience psychological symptoms like depression, anxiety, and mood changes, but psychosis is not a typical feature. B) Systemic hypertension: Hypertension is a common feature of Cushing's syndrome due to the effects of excess cortisol on blood pressure regulation. D) Osteoporosis: Excess cortisol can lead to bone loss and osteoporosis in Cushing's syndrome due to its negative effects on bone density. Educational context: Understanding the signs and symptoms of Cushing's syndrome is crucial for healthcare professionals in diagnosing and managing this condition. By knowing the typical manifestations, such as hypertension, osteoporosis, and psychological symptoms, clinicians can promptly identify and treat patients with Cushing's syndrome. Recognizing atypical features like sexual precocity can also aid in ruling out other conditions.

Correct Answer: A

Rationale: Congenital adrenal hyperplasia does not lead to dwarfism. It is a group of genetic disorders that affect the adrenal glands and can cause various symptoms related to hormone imbalances. In contrast, the other conditions listed - hypopituitarism, homocystinuria, and pseudohypoparathyroidism - can all lead to dwarfism through different mechanisms. Hypopituitarism is characterized by a deficiency of pituitary hormones, including growth hormone, which can result in stunted growth and dwarfism. Homocystinuria is a metabolic disorder that can affect bone growth and lead to skeletal abnormalities resulting in dwarfism. Pseudohypoparathyroidism is a rare genetic disorder that can manifest with short stature or dwarfism due to skeletal abnormalities caused by altered bone metabolism.

Correct Answer: B

Rationale: The triad of hyponatremia (low sodium levels in the blood), haemodilution (increased plasma volume), and urine hypertonic to plasma (high urine osmolality compared to blood osmolality) is characteristic of Syndrome of Inappropriate Antidiuretic Hormone (SIADH). In SIADH, there is excessive release of antidiuretic hormone (ADH), also known as vasopressin, leading to water retention by the kidneys and dilutional hyponatremia. This condition results in the body holding onto water, causing hyponatremia and dilution of the blood. The urine being hypertonic compared to plasma indicates that the kidneys are reabsorbing water effectively and concentrating the urine.