Rosacea is a chronic, inflammatory facial dermatosis characterized by recurrent flushing attacks and late permanent erythema, telangiectasia, papule and pustule1. We received the patient's consent form about publishing all photographic materials.

A 68-year-old male patient was referred to our outpatient clinic with complaints of flushing and rash on one side of the face. The patient stated that he had the complaint for a week and it started two days after his abscessed tooth extraction. The patient had a history of chronic obstructive pulmonary disease and has suffered flushing and mild papular lesions on both sides of the face for 15 years, especially at times with alcohol intake. The patient quitted alcohol 20 years ago and his complaint has disappeared since then. However, he recalled that his face was sensitive and got flushing attacks rarely. His examination showed plaque lesions mildly erupted on the right side of the face from the lower half of the forehead to the corner of the mouth, on the second trigeminal nerve area, with a zosteriform distribution. There was no supraorbital involvement. There were intense nonfollicular papules, pustules and squamas in the centre adhered to the skin (Fig. 1). The patient had a rhinophyma appearance on the nose and examination for demodex parasite was positive with 10~15 demodex per centimetre square. The Tzanck test and bacterial culture were both negative. Topical metronidazole and permethrin treatment were begun. After 15 days, his complaints were still continuing and demodex examination showed that the number of demodex had not decreased. Rosacea was considered and oral isotretinoin 20 mg/day was started. After one month, itching complaint and findings at the lesion site had disappeared completely except for a mild erythema. Biopsy was not taken since the lesions had recovered completely. After two months, there was no residual lesion on the face (Fig. 2).

Although the aetiology of rosacea is not well known, it is a multifactorial disease. Vascular hyperactivity or impaired activity and demodex mites are considered in the pathogenesis of this disease. Demodex parasites can contribute to the development of rosacea lesions by obstructing the follicular orifice mechanically or functioning as a vector to microorganisms1.

In the literature, there are three different cases with unilateral rosacea and a few cases with unilateral or psodozoster demodex. Shelley et al.2 reported a case with Demodex folliculorum and Demodex brevis parasites on one side of the face and the case had unilateral rosacea like chronic dermatitis. The remaining two cases were presented as neurogenic rosacea34. Our case had an appearance papulopustular rosacea rather than papulovesicular with a grouping tendency localized on one side of the face without any pain. There was no comorbid neurological involvement and responded well to isotretinoin treatment. The patient had also rhinophyma and one-sided classical rosacea lesions. Taken together, we think that these findings point to rosacea. We also think that intense social stress the patient suffered at that time together with extraction of his abscessed tooth two days earlier before this event may have triggered this clinical entity.