A 61-year-old woman presented with asymptomatic, diffuse round patches on the trunk for 1 month. The color of lesions changed gradually from erythematous to brownish and size of the lesions increased. The patient did not have any history of systemic diseases and familial history. A skin biopsy showed findings including hyperkeratosis with loss of normal basket weave pattern, loss of the granular layer and increased pigmentation at the basal layer. We diagnosed the eruption as pityriasis rotunda (PR) because of the circular configuration and the ichthyosis-like histopathological findings. Patient was treated with topical steroids and the eruptions gradually faded during these treatments. PR is a rare acquired disease of keratinization. It presents as well-defined, scaly round plaques that can be hyper- or hypopigmented. PR mainly affects young adults and shows no gender preference. It has been associated with systemic diseases and malignant tumors but the etiology is unknown. Concerning the pathogenesis of PR, Makino et al. recently described a reduction or absence of expression of filaggrin 2 in the epidermis of PR lesions, similar to the findings in lesions of atopic dermatitis, ichthyosis vulgaris, and psoriasis vulgaris. Treatment is difficult in most cases. Topical corticosteroids, antifungal agents, salicylic acid, topical and oral retinoids, lactic acid lotions and vitamin D3 have been used.