**Question:** A patient presents with Arthritis, hyperpigmentation of skin and hypogonadism, likely diagnosis is -

A. Systemic Lupus Erythematosus (SLE)
B. Vitiligo
C. Addison's Disease
D. Sickle Cell Anemia

**Correct Answer:** C. Addison's Disease

**Core Concept:** Addison's Disease is a rare endocrine disorder caused by the deficiency of adrenocorticotropic hormone (ACTH) or cortisol, resulting in impaired glucocorticoid and mineralocorticoid production. This leads to characteristic symptoms including fatigue, weight loss, hypotension, hyperpigmentation of skin, and sexual dysfunction (hypogonadism).

**Why the Correct Answer is Right:** Addison's Disease is caused by the deficiency of cortisol, a corticosteroid hormone, which helps in maintaining blood pressure, electrolyte balance, and immune system function. The symptoms of hyperpigmentation of skin and hypogonadism are specific to Addison's Disease.

**Why Each Wrong Option is Incorrect:**

A. Systemic Lupus Erythematosus (SLE): SLE is a systemic autoimmune disorder affecting multiple organs, causing widespread inflammation, and involves antinuclear antibody production. While arthritis is a common manifestation of SLE, hyperpigmentation and hypogonadism are not typical features of this disease.

B. Vitiligo: Vitiligo is a chronic autoimmune disorder characterized by the destruction of melanocytes, leading to skin depigmentation. It does not cause hyperpigmentation or hypogonadism.

D. Sickle Cell Anemia: Sickle Cell Anemia is a genetic disorder affecting hemoglobin production, leading to painful crises, organ damage, and frequent infections. It does not cause hyperpigmentation or hypogonadism.

**Clinical Pearl:** Addison's Disease is a crucial diagnosis to rule out in patients presenting with arthritis, hyperpigmentation, and hypogonadism, as these symptoms can be indicative of adrenal insufficiency. Timely diagnosis and treatment can prevent life-threatening complications.