Acta Dermato-Venereologica 99-2CompleteContent | Page 26

230 SHORT COMMUNICATION A Case of Perforating Folliculitis Induced by Vemurafenib Ken SHIRAISHI, Tae MASUNAGA, Mikiko TOHYAMA and Koji SAYAMA Department of Dermatology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan. E-mail: [email protected] Accepted Oct 3, 2018; E-published Oct 3, 2018 Vemurafenib, an oral BRAF kinase inhibitor, has been approved for the treatment of late-stage metastatic malignant melanoma. Although vemurafenib prolongs progression-free and overall survival, numerous cuta- neous side-effects have been reported (1, 2). We present here a case of perforating folliculitis (PF) associated with vemurafenib. To the best of our knowledge, this is the first report of vemurafenib-associated PF. CASE REPORT A 62-year-old man was treated with vemurafenib (960 mg twice daily) for metastatic malignant melanoma. Two months after ini- tiating therapy, numerous disseminated keratotic follicular papules developed on his scalp, face, trunk and legs (Fig. 1A, 3A). Each papule contained a central, cone-shaped, keratotic plug (Fig. 1B). Differential diagnoses included a perforating disorder, suppurative folliculitis, hyperkeratotic folliculitis, and keratosis pilaris. Histo- pathological examination showed a dilated follicular infundibulum filled with a mixture of keratotic material, basophilic debris and inflammatory cells (Fig. 2A). The follicular epithelium showed a perforation through which degenerated collagen fibres entered into the follicular cavity (Fig. 2B). The follicles were surrounded by inflammatory infiltrate, mainly comprising lymphocytes. Elastic Masson and Azan staining revealed invasion or penetration of collagen fibres into the follicular epithelium (Fig. 2C, 2D). A diagnosis of PF was established. Because of the clinical efficacy against metastatic melanoma, vemurafenib was maintained at the same dosage. Combined treatment with topical corticosteroid ointments and antibiotic ointments (nadifloxacin) did not improve the folliculitis. We initiated minocy- cline at 100 mg/day, but the skin lesions did not disappear (Fig. 3B). After vemurafenib was discontinued and changed to nivolumab due to tumour recurrence, follicular papules rapidly began to improve. One month after stopping vemurafenib, the skin lesions disappeared with residual pigmentation (Fig. 3C). We concluded that PF was a cutaneous adverse drug reaction due to vemurafenib. Fig. 1. (A) Numerous disseminated keratotic follicular papules on the trunk. (B) Each papule contained a central, cone-shaped, keratotic plug. mas, palmar-plantar keratoses, and keratosis pilaris-like eruptions, have been reported (1, 2). Acquired perforating dermatosis is an uncommon cutaneous perforating disorder characterized by trans- epidermal elimination of dermal tissue materials, such as keratin, collagen and elastic fibres. PF is an acquired perforating dermatosis together with Kyrle disease, DISCUSSION Vemurafenib is a small molecule that belongs to the group of protein kinase inhibitors. The drug has been appro- ved for the treatment of metastatic melanoma harbouring the BRAF muta- tion. Although vemurafenib prolongs progression-free and overall survival, numerous cutaneous side-effects, inclu- ding photosensitivity, alopecia, xerosis, squamous cell carcinoma, keratoacantho- doi: 10.2340/00015555-3059 Acta Derm Venereol 2019; 99: 230–231 Fig. 2. (A) Dilated follicular infundibulum filled with a mixture of keratotic material, basophilic debris and inflammatory cells. Haematoxylin and eosin staining; original magnification ×40. (B) Degenerated collagen fibres enter the follicular cavity through the follicular epithelium. Haematoxylin and eosin staining; original magnification ×100. (C) Elastic Masson staining reveals invasion or penetration of collagen fibres (green); original magnification ×200. (D) Azan staining detects collagen fibres (blue) invading into the follicular cavity; original magnification ×200. This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica.