[Persistent dyschromic erythema].
INTRODUCTION: Erythema dyschromicum perstans (ashy dermatosis) is a very rare skin disease included in the group of acquired, idiopathic hypermelanosis, with development of blue-gray macules. This disease appears more frequently in dark coloured persons, especially women in the first and second life decade. CASE REPORT: A male patient, 42 years of age, was admitted to Clinic of Dermatovenereology in Novi Sad due to appearance of slightly pruriginous, brown-reddish macules on the trunk, upper and lower extremities, without affecting the skin of the face, scalp, palm soles and visible mucous membranes. Later, the color of the macules changed into blue-gray and new lesions appeared in axilla and flexor side of the big joints, with active, erythematous and thin raised borders. Laboratory findings showed no abnormalities; antinuclear antibodies were negative. Histopathological examination of the skin specimens (which were taken from two different places) showed vacuolar degeneration of the basal cell layer, numerous pigmentophages in papillary dermis and presence of lymphohistiocytic infiltrate in dermis. No history of drug intake or exposure to UV light was established. DISCUSSION: Ashy dermatosis is included in the group of hypermelanosis of unknown origin. As possible etiological factors we can mention ingestion of ammonium nitrate, environmental pollution, hypersensitivity to cobalt chloride and postinflammatory pigmentation. Clinical characteristics: occurrence of blue-gray and gray macules on the trunk, face, neck and extremities (absence on the palms, soles, visible mucous membranes, scalp and nails). In the active phase of the disease, these macules are surrounded by erythematous and thin, raised borders. The lesions are mostly permanent. Due to clinical, histopathological, immunofluorescent and electron microscopy established similarities with lichen planus, it is considered that ashy dermatosis is a variant of lichen planus. Absence of previous drug intake, exposure to UV light, absence of the antinuclear antibodies, clinical picture and histological findings confirm the diagnosis of erythema dyschromicum perstans. CONCLUSION: This case of ashy dermatosis shows that there is a need for differential diagnosis of acquired skin pigmentations, because this dermatosis must also be taken into consideration.