<prompt> A 23-year-old male complains of recurrent scaly lesions on glans penis. It always occurred at the same site and healed with slight hyperpigmentation. What is the most likely diagnosis?Fixed drug eruptionHerpesCandida balanoposthitisBehcets disease  <response>: Ans. a. Fixed drug eruption Ref: Roxburghs 17e p95; Fitzpatrick 7e p359-60; Bahl 9e p270The most likely diagnosis in a 23-year-old male complaining of recurrent scaly lesions on glans penis, occurring at the same site and healed with slight hyperpigmentation is fixed drug eruption.Fixed Drug EruptionAdverse cutaneous drug reaction appearing soon after ingestionQ from 30 min to 8 hours of offending agent in previously sensitized individuals.Drugs Implicated in Fixed Drug Eruption PhenolpthaleinQ present in some laxatives BarbituratesQ MetronidazoleQ FluoroquinolonesQ SulphonamidesQ Cotrimoxazole, dapsone TertracyclineQ Salicylates and phenacetinQCharacteristic Features:Mucocutaneous junction lip, glans is most frequently involved, genital skin glans is the most commonly involved siteQ.Most commonly lesions are solitaryQ but they may be multiple.Lesions evolve from macules to papules to vesicles and bullae then erodeQ.Lesions heal by hyperpigmentationQUsually asymptomaticQ but may be pruritic, painful, or burning when erodedLesions persist if the drug is continued and resolve days to weeks after drag is continuedFDE occurs repeatedly at the same i.e. fixed site within hours, every time drug is taken and heals by residual grayish or slate colored hyperpigmentationQDiagnosis:Diagnosis is confirmed by provocation.Rechallenging the patient to the suspected offending drug is the only known test to possibly discern the causative agent.Treatment:The main goal of treatment is to identify the causative agent and avoid it.Symptomatic treatment: Systemic antihistamines and topical corticosteroids may be all that are required. 