Multiple sclerosis manifests as asymmetrical and in different parts of the body because:

Correct Answer: A

Rationale: The correct answer is A. Multiple sclerosis is characterized by the immune system attacking the myelin sheath in the central nervous system. This attack leads to patchy damage on the myelin sheath, resulting in asymmetrical neurological symptoms. Choices B, C, and D are incorrect because they do not accurately describe the pathophysiology of multiple sclerosis. In multiple sclerosis, it is the autoreactive lymphocytes that target and damage the myelin sheath, not acetylcholine receptors, T lymphocytes, or cortical motor cells.

Correct Answer: A

Rationale: The correct answer is A. Alpha-1 antitrypsin deficiency is a genetic condition that can lead to COPD at a young age, even in light smokers. Choice B is less likely as the patient's occupation does not directly correlate with alpha-1 antitrypsin deficiency. Choice C, a 70-year-old woman with a long smoking history, is more likely to have COPD due to smoking rather than alpha-1 antitrypsin deficiency. Choice D, exposure to secondhand smoke, is not a common cause of alpha-1 antitrypsin deficiency-related COPD.

Correct Answer: B

Rationale: The correct answer is B. Morbid obesity increases the risk of dehydration due to the larger body surface area and potential for greater insensible losses. Choices A, C, and D are less likely to experience dehydration compared to a morbidly obese individual.

Correct Answer: B

Rationale: The correct answer is B: Lifestyle modification and metformin. When managing type 2 diabetes mellitus, initial treatment often involves lifestyle changes such as adopting a healthy diet and increasing physical activity, along with the oral medication metformin. Insulin therapy (choice A) is usually reserved for cases where lifestyle changes and oral medications are not sufficient to control blood sugar levels. Sulfonylureas (choice C) and thiazolidinediones (choice D) are also oral medications used in diabetes management, but they are not typically recommended as first-line treatments due to various side effects and considerations in type 2 diabetes management.

Correct Answer: D

Rationale: The correct answer is D. Problems with tasks like meal preparation and balancing a checkbook can indicate cognitive impairment, as these activities involve cognitive functions such as memory, attention, and executive function. Choices A, B, and C are less indicative of cognitive impairment. Decreased interest in activities and increased complaints of physical ailments may be related to other factors like depression, while fear of being alone at night could be due to anxiety or other psychological issues.

Correct Answer: A

Rationale: The correct answer is A: Tuberculosis. Cavitary lesions in the upper lobes are classic findings seen in tuberculosis. This infectious disease commonly presents with symptoms such as chronic cough, night sweats, and weight loss. Pneumonia (Choice B) typically does not present with cavitary lesions on chest X-ray. Lung cancer (Choice C) may present with similar symptoms but is less likely to cause cavitary lesions in the upper lobes. Sarcoidosis (Choice D) usually presents with bilateral hilar lymphadenopathy and non-caseating granulomas, different from the cavitary lesions described in the case.

Correct Answer: B

Rationale: The correct answer is B because sudden onset of behavioral changes is a typical symptom of delirium. Delirium is characterized by an acute and fluctuating disturbance in attention, awareness, and cognition. Choice A is incorrect because delirium is not a normal part of aging. Choice C describes memory issues, which can be seen in delirium but are less specific than sudden behavioral changes. Choice D, while it mentions the patient's independence, does not directly support the diagnosis of delirium.

Correct Answer: D

Rationale: The correct answer is D. Hemangiomas, congenital dermal melanocytosis (i.e., Mongolian spots), and macular stains are birthmarks that usually fade or regress as the child gets older. Hemangiomas are vascular birthmarks that often shrink and fade over time. Congenital dermal melanocytosis (Mongolian spots) are blue-gray birthmarks commonly found on the lower back and buttocks of infants, which typically fade by adolescence. Macular stains, also known as salmon patches, are pink or red birthmarks that usually fade within the first few years of life. Choice D is correct because all the mentioned birthmarks tend to diminish as the child grows, unlike choices A, B, and C which do not fade or regress with age.

Correct Answer: C

Rationale: Dark urine is a classic symptom of rhabdomyolysis. When muscle breakdown occurs, myoglobin is released into the bloodstream and filtered by the kidneys, leading to dark urine. Paresthesias (choice A) refer to abnormal sensations like tingling or numbness and are not typically associated with rhabdomyolysis. Bone pain (choice B) is not a prominent symptom of rhabdomyolysis. Diarrhea (choice D) is not a common complaint in rhabdomyolysis cases and is not directly related to muscle breakdown.