Hypopigmented mycosis fungoides mimicking leprosy successfully treated with oral and topical corticosteroids: a new great imitator? Khairuddin Djawad 1 ✉ 1 Department of Dematology and Venereology, Faculty of Medicine, Hasanuddin University, Makassar, South Sulawesi, Indonesia. 83 2021;30:83-85 doi: 10.15570/actaapa.2021.20 Introduction Mycosis fungoides (MF) is the most common type of cutaneous T- cell lymphoma (CTCL), which is characterized by malignant mon- oclonal T-cell infltration of the skin (1). The clinical course of MF can be divided into three stages: patch stage, plaque stage, and tumor stage (2). The patch stage typically presents with asympto- matic to extremely pruritic erythematous patches that may last for decades before progressing to the plaque stage, although some stages can simultaneously be found (3). Hypopigmented MF (HMF) is a rare variant of patch stage MF, which presents as hypopigmented instead of erythematous patches (4). Unlike classic MF, which commonly occurs in the 5th and 6th decades, HMF tends to afect a younger population and has been reported in children (2). Due to its atypical presentation, it is ofen overlooked and mistreated as other hypopigmentation disorders. This case presents a young adult male with HMF who pre- sented with multiple longstanding asymptomatic hypopigmented patches, mistreated for leprosy. Case report A 35-year-old male presented with a chief complaint of non-prurit- ic white patches on his chest that had persisted for 10 years. The condition initially appeared on the chest, and the patches gradu- ally increased in size and number. The patient could not conf- dently state whether the patches were numb. The patient had previously been treated for leprosy using rifampicin, ofoxacin, and minocycline for 1 year without any signifcant improvement. No household members experienced the same complaint. The pa- tient reported no history of leprosy or malignancy. Physical examination showed that the patient was in good gen- eral condition with normal vital signs. Dermatological examina- tion revealed well-defned multiple hypopigmented patches and macules on the chest, posterior trunk, and gluteus; some lesions exhibited anhidrosis and central erythema (Fig. 1). Neurological examination did not show nerve enlargement or motor defcit; however, sensation impairment was difcult to assess due to the inconsistent result reported by the patient. Abstract Hypopigmented mycosis fungoides (HMF) is a rare variant of patch stage MF, which is ofen misdiagnosed. A 35-year-old male presented with non-pruritic white patches on his chest that had been present for 10 years. The patient had previously been treated for leprosy without any improvement. Physical examination showed well-defned multiple hypopigmented patches and macules on the chest, posterior trunk, and gluteus, with some lesions exhibiting anhidrosis and central erythema. The result of sensibility examination was unclear. Slit-skin-smear examination for acid-fast bacilli and anti-phenolic-glycolipid-1 examination were nega- tive. Histopathological examination showed Pautrier microabscesses. The patient was diagnosed with HMF and was treated with 16 mg methylprednisolone b.i.d., topical application of desoximetasone, and 1% methoxsalen lotion followed by sun exposure. A signifcant improvement was observed during the following 6 months. This case shows that HMF needs to be considered in patients presenting with chronic unexplained hypopigmented patches to avoid unnecessary treatment and progression to more advanced stages. Keywords: hypopigmented mycosis fungoides, leprosy, mimicking Acta Dermatovenerologica Alpina, Pannonica et Adriatica Acta Dermatovenerol APA Received: 27 February 2021 | Returned for modifcation: 3 May 2021 | Accepted: 6 May 2021 ✉ Corresponding author: duddin@ymail.com Figure 1 | Pre-treatment.