Hypocalcemia-related pustulosis: a case report

Abstract

Background

Hypocalcemia-related pustulosis is a rare dermatologic condition characterized by the development of sterile pustules on an erythematous base, associated with hypocalcemia. This condition is often misdiagnosed as generalized pustular psoriasis, presenting challenges in patient management. The novelty of this case lies in its emphasis on recognizing hypocalcemia as a potential cause of pustular eruptions, which can lead to significant clinical improvement once addressed.

Case presentation

A 34-year-old Moroccan woman with a history of total thyroidectomy and subsequent hypoparathyroidism presented with an acute, generalized pustular eruption. The lesions were diffuse, non-follicular, and symmetrically distributed across the trunk and limbs, accompanied by systemic symptoms such as muscle cramps and fatigue. Laboratory results confirmed severe hypocalcemia (serum calcium level: 52 mg/L; normal range: 85–105 mg/L) and low parathyroid hormone levels (6 pg/mL; normal range: 10–65 pg/mL), consistent with her prior hypoparathyroidism. A skin biopsy excluded psoriasis, steering the diagnosis toward hypocalcemia-induced pustulosis. The patient’s pustular eruption resolved dramatically within 24 hours after the initiation of calcium and vitamin D supplementation, with complete clearance over the following days.

Conclusions

This case highlights the critical role of investigating electrolyte imbalances, particularly hypocalcemia, in patients with unexplained pustular eruptions. Prompt calcium correction led to rapid and complete resolution of the skin lesions, demonstrating the direct link between hypocalcemia and pustulosis. This emphasizes the importance of early diagnosis and appropriate management to ensure full clinical recovery.

Introduction

Hypocalcemia-related pustulosis is a rare dermatologic condition characterized by the development of sterile pustules on an erythematous background, associated with hypocalcemia. Correction of this electrolyte imbalance typically leads to resolution of the cutaneous lesions. This pustulosis presents diagnostic challenges, particularly due to its similarity with generalized pustular psoriasis, making the management of patients’ cases more complex. This clinical case highlights the importance of recognizing hypocalcemia as a potential cause of pustular dermatosis.

Case presentation

We report the case of a 34-year-old Moroccan woman with a history of total thyroidectomy performed 10 years prior, which was complicated by permanent postoperative hypoparathyroidism and chronic hypocalcemia requiring lifelong supplementation. The patient had been prescribed calcium carbonat (1 g/day) and calcitriol (0.5 μg/day). However, the patient demonstrated poor adherence to her prescribed treatment due to financial contraints.

Upon clinical examination, the patient presented with acute generalized pustular eruption, characterized by diffuse pustules arranged on an erythematous base. These pustules were sterile and distributed predominantly across the trunk and limbs, with involvement of the upper and lower extremities, abdomen, and back. The borders of the pustules were well defined, and they were not localized to any specific skin folds or areas of friction (Fig. 1). The patient also reported accompanying systemic symptoms, including muscle cramps, fatigue, and paresthesia.

Fig. 1.

Clinical aspect at admission showing generalized pustular eruption with diffuse pustules on the erythematous base primarily affecting the trunk and extremities

Laboratory results confirmed severe hypocalcemia (serum calcium level: 52 mg/L; normal range: 85–105 mg/L) and low parathyroid hormone levels (6 pg/mL; normal range: 10–65 pg/mL), confirming hypoparathyroidism as the underlying cause of hypocalcemia. Other tests revealed normal albumin levels and renal function, ruling out renal insufficiency as a contributing factor to the calcium imbalance. To rule out Fahr syndrome, a cerebral computed tomography (CT) scan was also performed, and results were normal.

To further investigate the etiology of the eruption, a skin biopsy was performed. Histopathological examination did not reveal any signs indicative of psoriasis. This finding, along with the clinical presentation and the laboratory results, helped exclude psoriasis and steered the diagnosis toward hypocalcemia-induced pustulosis. Other potential inflammatory causes and drug-induced eruptions were also considered and excluded.

The correction of hypocalcemia was achieved through the administration of intravenous calcium. The patient received 200 mg of elemental calcium over a 15-minute infusion and then 1.5 mg/kg/hour over 6 hours with continuous ECG monitoring. Serum calcium levels were monitored every 6 hours to adjust the treatment accordingly. In addition to calcium supplementation, the patient was prescribed calcitriol (1,25(OH)₂D₃) at a dose of 1 µg per day orally. Once the patient’s calcium levels stabilized, oral maintenance therapy was introduced with calcium carbonate at a dose of 1 g/day. After initiating treatment, the patient experienced a remarkable clinical improvement within the first 24 hours (Fig. 2), with the pustular lesions beginning to resolve and associated systemic symptoms such as muscle cramps and paresthesia markedly decreasing. Over the following days, the pustular eruption cleared entirely (Fig. 3). After a 1-year follow-up, no recurrence of the pustular eruption was noted following long-term stabilization of the patient’s calcium levels.

Fig. 2.

Clinical aspect 24 hours after the start of supplementation showing a remarkable improvement with no more pustular lesions

Fig. 3.

Clinical aspect 3 days after the start of supplementation showing a complete disappearance of the lesions

Discussion

This case highlights an association between hypocalcemia and generalized pustulosis, which can occur in patients with or without a history of psoriasis [1].

The etiological assessment of hypocalcemia, in the absence of obvious clinical situations, relies on measuring circulating parathyroid hormone (PTH) levels, which allows differentiation between parathyroid and extra parathyroid causes. The presence of hypocalcemia with low and inappropriate PTH is generally a consequence of thyroid or parathyroid surgery. Other causes are much rarer, such as the infiltration of the parathyroids, activation of the calcium-sensing receptor, or isolated or syndromic congenital deficiency in PTH secretion [2]. The presence of hypocalcemia with elevated and appropriate PTH is typically secondary to vitamin D deficiency, chronic renal failure, or a sudden drop in plasma ionized calcium due to precipitation or transfer [3, 4].

The exact pathophysiological link between hypocalcemia and generalized pustulosis remains unclear. However, several hypotheses have been proposed: For example, calcium plays a crucial role in regulating keratinocyte proliferation and differentiation [5], and therefore, its deficiency could trigger an exaggerated inflammatory skin response [6]. In addition and the genetic mutations in the IL36RN gene, which is involved in skin inflammation regulation, have been reported in some patients with generalized pustulosis associated with hypocalcemia, suggesting a genetic predisposition [7].

Conclusion

This case underscores the importance of investigating electrolyte imbalances, particularly hypocalcemia, in patients presenting with unexplained pustular eruptions. The prompt resolution of lesions following calcium correction confirms the direct association between hypocalcemia and pustulosis. Early and appropriate management of hypocalcemia ensures complete clinical recovery.

Abbreviations

PTH

Parathyroid hormone

CT

Computed tomography

Author contributions

EA: corresponding author, patient follow-up, and writing the paper. EF: patient follow-up and correction of the paper. RH: Validation of the paper. HF: Validation of the paper. SC: Validation of the paper.

Funding

No funding was received for this study.

Data availability

All relevant data supporting the findings of this study are included within the manuscript.

Declarations

Ethics approval and consent to participate

Given the nature of this case presentation and in accordance with institutional policies, ethical approval was not required.

Consent for publication

Written informed consent was obtained from the patient for publication of this case presentation and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Competing interests

The authors declare that there are no conflict of interest.