A 7-year-old girl develops red macules that coalesce into large patches distributing over more than half of the body especially the face and trunk; the lesions evolve rapidly into bullae. Her lips are swollen and red with erosion of the oral mucosa. She has also bilateral conjunctival injections and erosions. She has a history of fever, malaise, and upper respiratory symptoms ten days before. Of the following, the MOST likely diagnosis is

Correct Answer: C

Rationale: Toxic epidermal necrolysis (TEN) is likely due to extensive skin involvement, bullae, and mucosal erosions, often triggered by drugs or infections.

Correct Answer: B

Rationale: Eccrine sweat glands are distributed across the body and secrete a watery sweat to regulate temperature, unlike sebaceous glands which produce sebum.

Correct Answer: C

Rationale: Folic acid synthesis is not a protective function of the skin; the other options (stratum lucidum, desmosomes, Merkel cells) contribute to structural integrity or sensation.

Correct Answer: C

Rationale: Excessive sun exposure is a major risk factor for skin cancers, and limiting it can reduce risk; they can spread beyond the epidermis if untreated.

Correct Answer: C

Rationale: Squamous cell carcinoma originates from keratinocytes in the stratum spinosum, which can metastasize if untreated.