Boils? Or coils?

Abstract

In January, 1999, a 42-year-old Chinese housewife, from a mountainous region, developed pustules on both feet, and severe itching. Her illness became worse during her menstrual period, when pustules spread to her legs and buttocks, and she developed a fever as high as 40oC. She developed osteomyelitis of the fourth and fi fth toes of the left foot, which were amputated. She was otherwise healthy. She had no family history or clinical features of psoriasis. Topical antiseptics, systemic antibiotics, and nonsteroidal anti-infl ammatory drugs were all ineff ective. Remarkably, perhaps, oral steroids were never prescribed. 6 years after her illness began, the patient was referred to the orthopaedics department at our hospital, because of the diagnosis of osteomyelitis. Blood tests, including concentrations of oestrin and oestrogen, a full blood count, a metabolic screen, an ESR, and immunological testing (including concentrations of immunoglobulins) showed nothing abnormal. Culture of fl uid from previously intact pustules revealed no bacterial growth; acid-fast staining gave a negative result. Since the source of osteomyelitis had not been identifi ed, an orthopaedic surgeon requested MRI of the abdomen, pelvis, and legs; in preparation for this scan, the patient’s intrauterine contraceptive coil (intrauterine device; IUD) was removed. Within 1 month, the pustules and itching had gone. We noted that the IUD had been implanted around 2 years before the illness began. Although the patient had had no symptoms of abdominal or pelvic illness, we suspected that the patient was allergic to the coil. Since copper and nickel are the main components of an IUD, we did patch testing with copper sulphate (2·5% in petrolatum) and nickel sulphate (5% in petrolatum) simultaneously, according to the guidelines of the International Contact Dermatitis Research Group, with a Finn chamber. 30 h after the patches were applied, papules developed on the skin under the copper patch, which became itchy and very red. The patient then developed a fever of 39o C, and became very itchy all over her body. Intraepidermal pustules, like those seen during the patient’s illness, developed on her legs and feet (fi gure). The skin that had been under the nickel patch was unchanged. Concentrations of complement fractions C3 and C4, antinuclear antibody, and antibodies to double-stranded DNA and extractable nuclear antibody were normal, as were results of a full blood count and urine testing. We measured the serum copper concentration with atomic fl uorescence spectrometry, and found it to be high, at 2·06 mg/L (normal range 0·47–1·40 mg/L). We diagnosed plantopalmar pustolosis, and prescribed an oral corticosteroid and cetirizine. Within 1 month, the patient’s skin was normal again. When last seen, in February, 2008, the patient was well— and using a diff erent form of contraception. Allergic reactions to metals can cause classic contact dermatitis, which is localised, or systemic contact dermatitis, typically characterised by dyshidrosis, pustulosis, and urticaria. Palmoplantar pustulosis, a type of systemic allergic contact dermatitis, can, rarely, be caused by metal implants; IUDs containing copper have been reported to cause other types of systemic contact allergic dermatitis. Copper is ionised within the body. Women with some types of IUD have high concentrations of copper in cervical mucus. Animal studies, with radiolabelled copper, have shown that copper from IUDs is absorbed through the mucus membrane, and travels to the skin through blood or lymphatic vessels (it is also deposited elsewhere in the body). Copper reacts with proteins, to form a complex that can be detected by the immune system. We speculate that Langerhans cells, which are abundant in the uterus, acted as antigenpresenting cells. The pronounced response to patch testing may have been caused by the length of previous exposure.