Generalized pustular psoriasis with hypoparathyroidism

ARTICLE

Generalized pustular psoriasis is precipitated by various factors and, in some cases, is associated with hypocalcemia [1, 2]. We report a case of generalized pustular psoriasis with hypocalcemia due to hypoparathyroidism. In addition, the case presented here is characterized by acantholysis in the epidermis.

Case report

A 36-year-old Japanese woman with psoriasis vulgaris had been treated for 19 years. At 24 years of age, she had pustular eruptions with tetany and fever. She had been diagnosed with generalized pustular psoriasis with associated hypoparathyroidism, and had been treated with calcium supplements and calcitriol, etretinate, and topical and systemic steroids. She had used only topical steroids for the past two years. In November, 1997, at 36 years of age, she had generalized cutaneous eruptions, an elevated temperature, and general malaise, a week after she caught a cold. Physical examination on admission showed a febrile patient with erythroderma and generalized pustules that tended to coalesce (Figs. 1 and 2). Laboratory tests revealed a white blood cell count of 27,900, total serum calcium of 3.8 mg/dl and serum albumin of 2.1 g/dl. Serum calcium corrected by serum albumin was 5.32 mg/dl.

Light microscopic examination of a pustule showed the formation of intraepidermal pustules underneath the stratum corneum including spongiform pustules (Fig. 3). In the dermis there was a perivascular infiltrate of lymphocytes and neutrophils. The epidermis revealed acantholysis (Fig. 4).

Treatment consisted of parenteral rehydration, oral and parenteral calcium at 2 to 5 g per day, oral 1,25-dihidroxyvitamine D (calcitriol at 1.0 to 2.0 g per day), serum albumine and antibiotics. Gentamicin and steroid ointments were used topically. Twelve days later, we started to administer etretinate at 25 to 50 mg per day. Over the next few days calcium levels became normal, pustules disappeared and erythroderma resolved completely in the following week (Fig. 5). Eight months later, psoriatic plaques were present only on the elbows. We continue to treat her with oral calcitriol, oral calcium and etretinate.

Discussion

Hypocalcemia is often revealed in generalized pustular psoriasis and is regarded as a secondary phenomenon related to hypoalbuminemia. There have been reports on generalized pustular psoriasis associated with hypoparathyroidism as in the present case, which were cured by correction of hypocalcemia using calcium and vitamin D [1, 2]. The calcium level was low whenever our patient showed relapses of pustules. This low calcium level was not seen to be due to hypoalbuminemia, since it remained low even when corrected by serum albumin. When the calcium level became normal, the pustules improved, and erythroderma resolved completely. In hypoparathyroidism, only very low levels of, or no parathyroid hormone is secreted, which leads to low vitamine D activity and hypocalcemia. Vitamin D and its analogs affect cell differentiation, cell proliferation, and immunity [3-5]. It was suggested that hypocalcemia may damage cell adhesion molecules, such as cadherins which depend on calcium, in our patient. Pemphigus characterized by acantholysis is also considered to be an autoimmune disease associated with anticadherin [6]. Darier disease shows damage to the cadherins in the epidermis [7]. Sakuntabhai has recently found a mutation in ATP encoding a Ca²⁺pump, causing Darier disease [8]. Furukawa reported on cadherin expression when the calcium concentration was changed in mouse cell cultures [9]. When the concentration of extracellular calcium is changed, cell-cell contact and E-cadherin are reduced in human keratinocytes [10]. However acantholysis may appear frequently an as epiphenomena in numerous diseases without calcium disoders [11]. There should be more discussion on this point in the future.

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