Eighty years have elapsed since fixed drug eruption was described (Brocq, 1894) but the mechanism of production is still unknown. Both immunological and toxic mechanisms have been implicated to explain the abnormal response of the skin to the administered drug, but there is no supporting evidence in either direction. Patch testing was used in the past to explain this phenomenon but the results were conflicting (Loveman, 1934;Baker, 1962). Other investigators have performed exchange full-thickness skin grafts with skin from the sites of the fixed drug eruption. The affected skin lost its hypersensitivity when transplanted to a site of normal skin while, the normal skin became hypersensitive when transplanted to an area of previous reaction (Knowless et al., 1936;Baker, 1962). Conflicting results were also obtained by intradermal injection of the responsible drug into the hyperpigmented areas (Stritzler and Kopf, 1960;Tan, 1974). Wyatt et al. (1972) reported the presence of a humoral agent in the serum of a patient with fixed drug eruption at the acute phase of the disease; while Gimenez-Camarasa et al. (1975) in a study of 21 patients showed that in the lymphocyte transformation test, when autologous serum taken at the acute phase of the eruption was added, blast transformation of the lymphocytes was produced. Recently Theodoridis et al. (1977) reported the presence of elevated IgG and IgA in the serum of 47 patients with fixed drug eruption at the acute phase of the disease while after remission, levels returned to normal.
Deposition of immunoglobulins, C3 and fibrin in the lesions of fixed drug eruption is not mentioned in the available literature on the subject. For that reason this study was undertaken to investigate the possibility of deposition of immunoglobuline, C3 and fibrin in the epidermis of 5 patients with fixed drug eruption.
Skin samples from the affected areas were obtained with a punch biopsy from all patients with fixed drug eruption. The duration of the eruption, the responsible drug and the presentation of the eruption (first or more times) are listed in Table 1.