A 58-year-old woman is diagnosed with osteoarthritis (OA) in her hips. Which of the following most closely describes the pathophysiology of OA?

Choice A reason: While stress and environmental factors may exacerbate acne, they are not the primary pathophysiological mechanism. Acne vulgaris is fundamentally driven by changes in the pilosebaceous unit, not psychological or allergenic triggers alone.

Choice B reason: UVA/UVB exposure may contribute to skin damage and inflammation, but it is not the direct cause of acne. In fact, some UV exposure may temporarily suppress inflammation, though it is not a therapeutic strategy and does not explain the formation of acne lesions.

Choice C reason: Acne vulgaris results from obstruction and inflammation of pilosebaceous units. This process begins with increased sebum production, follicular hyperkeratinization, and colonization by Cutibacterium acnes, leading to comedones and inflammatory lesions such as papules, pustules, and nodules.

Choice D reason: Keratinocyte proliferation and differentiation abnormalities are more characteristic of conditions like psoriasis. While keratinization plays a role in acne, this description does not fully capture the multifactorial pathogenesis involving sebum, bacteria, and inflammation.

Choice A reason: Polysomnography is a comprehensive overnight sleep study used to diagnose sleep disorders such as obstructive sleep apnea, parasomnias, and periodic limb movement disorder. While it provides objective data on sleep architecture and disturbances, it does not specifically distinguish between subjective feelings of fatigue and actual dozing behavior during the day.

Choice B reason: The Multiple Sleep Latency Test (MSLT) is an objective test that measures how quickly a person falls asleep in a quiet environment during the day. It is used to assess excessive daytime sleepiness and diagnose conditions like narcolepsy. However, it does not capture subjective experiences or differentiate between fatigue and sleepiness based on self-report.

Choice C reason: The Epworth Sleepiness Scale is a validated self-administered questionnaire that evaluates the likelihood of dozing off in various daily situations. It is specifically designed to distinguish between general fatigue and actual sleepiness by assessing the propensity to fall asleep, making it the most appropriate tool in this scenario.

Choice D reason: CSF hypocretin measurement is used in the diagnosis of narcolepsy type 1, where hypocretin levels are typically low. While it is a biomarker for a specific sleep disorder, it does not help differentiate between fatigue and sleepiness in broader clinical contexts and is not a practical screening tool for general sleep complaints.