Case report Meralgia paresthetica successfully treated with topical 0.1% tacrolimus: a case report Carina M. Gr€ onhagen, MD, PHD, and Hong Liang Tey, MBBS, FRCP, FAMS National Skin Center, Singapore City, Singapore Correspondence Hong Liang Tey, MBBS, FRCP, FAMS National Skin Center 1 Mandalay Road 308 205 Singapore E-mail: teyhongliang111@yahoo.com Conflicts of interest: None. Meralgia paresthetica (MP) is a rare localized neuropathic itch secondary to nerve entrapment of the lateral femoral cutaneous nerve, typically presenting with pruritus (some- times with pain and dysesthesia) localized to the unilat- eral anterolateral thigh. 1 No effective and lasting topical treatment has been reported. Case report A 56-year-old Indian woman with hyperlipidemia, hyperten- sion, and obesity underwent bariatric surgery. Thirteen days post surgery, she felt itching and pain over her right lower thigh. For the next 3 months, she experienced intermittent itching in the morning (of intensity 7/10 on a combined visual analogue and numerical scale) and intense intermit- tent pain at night (of intensity 7/10). Examination revealed a localized area of excoriations over her right lower lateral thigh without the presence of a primary dermatosis. The area of itch/pain and excoriations correlated with the distribution of the lateral cutaneous branch of the femoral nerve. She was treated with topical 0.1% tacrolimus twice daily over the affected area. After 1 week, both her itching and pain had resolved. She did not experience any side effects. She reduced the application to once daily at 2 months and stopped applying at 4 months. There was no recurrence of symptoms up to the current follow-up at 10 months. Discussion Our patient presented with the typical clinical features of MP and a supportive history of recent bariatric surgery. The use of topical tacrolimus has not been previously reported in MP, but it has been reported in another neuro- pathic itch, notalgia paresthetica, 2 and its antipruritic effect has been reported in atopic dermatitis, 3 as well as in a few chronic pruritic conditions. 4,5 The exact mechanism of action of topical tacrolimus in MP is not known, but it is believed to have a capsaicin-like effect and may mediate its antipruritic effect through activation of the transient receptor potential vanilloid 1 (TRPV1) located on periph- eral nerve fibers. 6,7 After activation of this ion channel, nerve fibers are depolarized, resulting in the transmission of pain signals. Transmission of pain inhibits itch signal- ing and along with continuous stimulation of the TRPV1, the nerve fibers may be finally desensitized, resulting in discontinued transmission of nociceptive signals. These findings may provide a possible explanation for the pro- gressive and efficacious reduction of itch and pain after application of topical tacrolimus in our patient. MP is often difficult to treat, and treatment often involves systemic drugs with potential adverse effects and drug interactions. Topical tacrolimus is therefore an appealing treatment alternative. This is the first report on the effective treatment of MP using topical tacrolimus, and further studies are needed. References 1 Bolognia JL, Jorizzo JL, Schaffer JV. Dermatology, 3rd edn. USA: Elsevier Saunders, 2012: 120–123. 2 Ochi H, Tan LX, Tey HL. Notalgia paresthetica: treatment with topical tacrolimus. J Eur Acad Dermatol Venereol 2014; doi:10.1111/jdv.12830. [Epub ahead of print]. International Journal of Dermatology 2016, 55, e32–e33 ª 2015 The International Society of Dermatology e32