Nail psoriasis masqueraded by secondary infection with Rhodotorula mucilaginosa

A 38-year-old man presented with whitish nail changes on all fingers as the sole symptom. The condition had developed within a few days and led to dystrophy of the proximal part of the nail plates. As microscopic examination of nail scrapings demonstrated budding hyphae and the patient working as a teacher reported frequent use of a wet sponge, antifungal therapy was initiated. Subsequent cultures and molecular typing identified Rhodotorula mucilaginosa (formerly R. rubra). This environmental yeast was repeatedly isolated despite of therapy with itraconazole. As no improvement was achieved and testing of the biological activity of the fungus revealed only marginal keratolytic activity, it was considered as a coloniser of a destructed nail matrix. Finally, a biopsy of the nail bed confirmed the diagnosis of nail psoriasis, which rapidly responded to treatment with acitretin and topical calcipotriol/betamethasone cream. Fungal growth in destructed nails masqueraded the underlying disease and may have triggered the psoriatic nail reaction.