02527nas a2200205   4500000000100000008004100001260001900042653003400061653002600095653003300121100001200154700001000166700001100176245009700187856026000284300001000544490000700554520174600561022001402307       2026                            d  c09/2026bLepra10aLepromatous leprosy diagnosis10adiagnostic challenges10aStill's Disease, Adult-Onset1 aZhang L1 aGuo Q1 aQiao L00aLepromatous leprosy presenting as adult-onset Still's disease: a 5-year diagnostic challenge  uhttps://www.researchgate.net/publication/413067992_Lepromatous_leprosy_presenting_as_adult-onset_Still's_disease_a_5-year_diagnostic_challenge/fulltext/6aae18b66b2ede2d2aab7d22/Lepromatous-leprosy-presenting-as-adult-onset-Stills-disease-a-5-year-diagnost  a1 - 80 v973 a<p>Leprosy, known as the “great imitator”, can present with systemic inflammatory manifestations that closely resemble autoimmune diseases, particularly during type 2 leprosy reactions (erythema nodosum leprosum, ENL). We report a 23-year-old Chinese male with a 5-year history of recurrent fever, arthralgia, papular and nodular skin lesions, and generalised lymphadenopathy. He met Yamaguchi criteria for adult-onset Still’s disease (AOSD) and received prolonged immunosuppressive therapy with glucocorticoids, methotrexate, hydroxychloroquine, and adalimumab but experienced recurrent flares upon steroid tapering. Skin biopsy from a right costal margin lesion revealed a dense dermal infiltrate predominantly composed of foamy histiocytes, with collagen degeneration and periadnexal lymphohistiocytic inflammation. Well-formed granulomas were absent. Acid-fast staining (Ziehl-Neelsen) demonstrated abundant acid-fast bacilli within the foamy histiocytes forming characteristic globi, and Wade-Fite stain confirmed Mycobacterium leprae with a high bacterial index. The diagnosis was revised to lepromatous leprosy with type 2 reaction (ENL). After referral for multidrug therapy (MDT) and gradual prednisolone tapering, the patient achieved complete clinical remission with normalisation of inflammatory markers. This case underscores a critical diagnostic pitfall for dermatopathologists and clinicians: in non-endemic regions where clinical suspicion for leprosy is low, the histopathologic finding of a foamy histiocytic infiltrate without granuloma formation should prompt acid-fast staining to exclude lepromatous leprosy, particularly in patients with unexplained systemic inflammation and epidemiologic risk factors.</p>
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