Correct Answer: A

Rationale: The clinical findings of thin hair, exophthalmos (bulging eyes), hyperreflexia, and pretibial edema are classic manifestations of Graves disease, an autoimmune condition that results in hyperthyroidism. Choice B is incorrect because weight gain and constipation are more indicative of hypothyroidism, not hyperthyroidism seen in Graves disease. Choice C is incorrect as the symptoms described are more characteristic of hypothyroidism, not hyperthyroidism. Choice D is also incorrect as the symptoms listed are not consistent with Graves disease but rather suggest hypothyroidism.

Correct Answer: C

Rationale: Osteosarcoma is an aggressive bone tumor that most commonly arises in the bone marrow of long bones, such as the femur or tibia. Choice A is incorrect as osteosarcoma is not a slow-growing tumor but rather a fast-growing one. Choice B is incorrect as osteosarcoma is not typically solitary but can involve multiple lesions. Choice D is incorrect as osteosarcoma primarily affects the medullary (marrow) cavity of bones, rather than infiltrating the trabeculae in spongy bone and surrounding tissue.

Correct Answer: A

Rationale: Abrupt withdrawal or discontinuation of prednisone, a corticosteroid, can lead to adrenal crisis. This occurs due to the suppression of the adrenal glands' natural cortisol production caused by prolonged exogenous steroid administration. Adrenal crisis presents with symptoms such as weakness, fatigue, abdominal pain, and hypotension. Hypercortisolism (Cushing syndrome) results from chronic excessive exposure to cortisol, not abrupt withdrawal. ACTH stimulation would be expected in response to low cortisol levels, not as a direct consequence of prednisone withdrawal. Thyroid crisis (thyroid storm) is associated with severe hyperthyroidism and is not directly related to corticosteroid withdrawal.

Correct Answer: D

Rationale: Anemia of chronic inflammation is typically characterized by normochromic (normal hemoglobin content) and normocytic (normal cell size) red blood cells. Choice A, hypochromic and microcytic, is incorrect because hypochromic refers to reduced hemoglobin content and microcytic refers to smaller than normal red blood cells, which are not typically seen in anemia of chronic inflammation. Choice B, hypochromic and macrocytic, is also incorrect as macrocytic refers to larger than normal red blood cells. Choice C, normochromic and microcytic, is incorrect because microcytic red blood cells are smaller than normal. Therefore, the correct classification for anemia of chronic inflammation is normochromic and normocytic.

Correct Answer: C

Rationale: Multiple sclerosis is characterized by the immune system mistakenly attacking the myelin sheath in the central nervous system. This results in the formation of lesions that can occur in different parts of the central nervous system, leading to varied symptoms depending on the location of the damage. Choice A is the correct answer because it accurately describes the pathophysiology of multiple sclerosis. Choices B, C, and D are incorrect because they describe mechanisms or locations that are not associated with the pathogenesis of multiple sclerosis.