Erythema nodosum recurred in a woman during each of her four pregnancies and every time she was started on oral contraceptives. The lesions always disappeared in the fifth month of gestation or when contraceptives were withdrawn. Erythema nodosum is mediated by immune mechanisms, and both pregnancy and oral contraceptive use can interfere with the immune system. The concentrations of oestrogen and progesterone or the ratio between them may be critical to the development of erythema nodosum. The observation that the lesions spontaneously resolved in the fifth month of pregnancy supports this hypothesis.
PIP: The case of a woman with erythema nodosum occurring during each of 4 pregnancies and every time she was started on oral contraceptives (OCs) is reported. The onset of the disease was between the 2nd-5th months of pregnancy, disappearing after the 5th month. During a period in which she had been taking DL-norgesgrel .25 mg and ethinyl estradiol .05 mg the erythema nodosum was found to be resistant to cessation of OC therapy and to treatment. At examination she was found to have a sedimentation rate of 84 mm in 1 hour, raised seromucous levels, and considerably increased IgA. 8 days after all medication was stopped the erythrocyte sedimentation rate dropped.to 21 mm in 1 hour. Erythema nodosum is mediated by immune mechanisms. Both OCs and pregnancy can disrupt the immune system. The concentration of estrogen to progesterone may be criticalin the development of the symptoms as can be seen by the disappearance of the disorder in the 5th month of pregnancy.