Topical TRPM8 agonist (icilin) relieved vulva pruritus originating from lichen sclerosus et atrophicus.

Pruritus vulvae is caused by a variety of skin diseases, as well as by neuropathic/neurological, psychosomatic and psychiatric diseases. It is difficult to determine the pathogenesis of itching symptoms over the vulval area, but ongoing inflammatory reactions, may be responsible for lowering the perception threshold of itching (1, 2). A variety of topical treatments has been used to reduce genital pruritus, including menthol, camphor, tannin preparations, local anaesthetics, antiseptics, urea preparations , glucocorticosteroids, immunomodulators and N-palmitoyl-ethanolamine-containing cream (3). General advice for relief of pruritic symptoms include avoiding sweating and occlusion of the skin, and reducing potential irritative cleansing habits. Empirical observation supports the use of cold compression over the pruritic skin lesion to relieve unpleasant nociception, such as itch and sensation of heat. Thus, local cooling sense evoked by TRPM8 activation can give a wisdom of controlling pruritus as shown in this case. A 54-year-old woman was referred from the department of gynaecology due to uncontrolled itching over the vulval area, which had persisted for one year. She had a history of total hysterectomy for stage T1aN0Mx endometrial carcinoma 3 months previously, but the ongoing itching sensation had not changed after surgery. Physical examination revealed a genital lesion with excoriated lichenification on whitish atrophic linear patches along the labia major (Fig. 1). The patient had been screened for psychiatric disorders such as depression, anxiety, delusion and obsessive compulsive disorder, but no reliable association was revealed. We asked her to report the itch intensity in several occasions using a visual analogue scale (VAS) (range: 0 = none to 10 = extreme). Her response was always 9. Laboratory test results, including white blood cell counts, and kidney and liver functions, iron and glucose levels, were all within normal limits. Mycological examination and Papanicolaou test results were negative or non-contributory. Skin biopsy was performed and histopathology revealed a thin epidermis with a wide band of hyalinization in the upper dermis mixed with lymphohistiocytic infiltrates suggesting a typical pattern of lichen sclerosis et atrophicus (Fig. 2). Various topical agents, such as glucocorticoids, antifungal, oestrogen cream, including intralesional triamcinolone injection were all ineffective. The patient reported paroxysmal itching symptoms , sometimes related to sleep disturbance, thus we looked for a new agent that could directly affect the itching afferent sensory perception. Menthol is a well-known TRPM8 receptor agonist, which has been used as an additive in topical formulations to evoke a fresh cooling sensation. However, …