Fixed Drug Eruption

A 32-year-old woman presents with a solitary, well-demarcated, dusky-red plaque on the dorsum of her right hand that appeared 3 days after she started trimethoprim-sulfamethoxazole for a urinary tract infection. She reports mild burning sensation at the site. On examination, the lesion is round, 2 cm in diameter, with a violaceous hue and central erosion. She has no systemic symptoms. She stopped the antibiotic 2 days ago. What is the most likely diagnosis?

A 28-year-old man with recurrent genital herpes simplex virus infection presents with a dusky-red, round macule on the glans penis that appeared 4 days after he restarted acyclovir for an HSV flare. He reports that an identical lesion appeared at the same site 6 months ago when he took acyclovir for a previous episode. The lesion is asymptomatic and does not blanch with pressure. Histopathology shows basal cell necrosis with melanin incontinence and a sparse lymphocytic infiltrate. What is the most likely diagnosis?

A 32-year-old woman presents with a single, well-demarcated, dusky red macule on the dorsum of her right hand that appeared 48 hours after she took trimethoprim-sulfamethoxazole for a urinary tract infection. She reports that the lesion is mildly itchy and tender. On examination, the lesion measures 2 cm × 1.5 cm and has a slightly raised, edematous border. She recalls a similar lesion at the exact same site 6 months ago after taking the same antibiotic, which resolved spontaneously within 2 weeks. What is the most likely diagnosis?

A 28-year-old man from Delhi presents with a painful, dusky-red nodule on the glans penis that has persisted for 3 weeks. He reports that he took oral ampicillin for a throat infection 3 weeks ago and the lesion appeared within 2 days of starting the antibiotic. He stopped the ampicillin 2 weeks ago, but the lesion has not resolved. On examination, the nodule is 1.5 cm in diameter, non-blanching, and tender to palpation. There is no vesiculation, crusting, or purulent drainage. He denies any systemic symptoms, fever, or lymphadenopathy. What is the most appropriate next step in management?