INTRODUCTION

Pustular psoriasis of pregnancy, or impetigo herpetiformis (IH), is a rare gravidic dermatosis that occurs mainly during the third trimester of pregnancy and usually disappears after delivery; however, there is a possibility of recurrence in subsequent pregnancies. Generally, the recurrence of IH is characterized by a more severe natural evolution and an earlier onset in subsequent pregnancies, recurrences may occur more exceptionally in the postpartum period.

Herein, we report the case of our patient who presented two episodes of pustulosis, one in each pregnancy, with a total remission after the first delivery, a partial remission after the second delivery, then reappearance of the condition five months later in postpartum.

CASE REPORT

This was a forty-year-old patient with a history of a similar episode during the fourth month of her first pregnancy, with complete remission after parturition. She had a further episode during her second pregnancy at the end of the second trimester, when a skin biopsy was performed in favor of impetigo herpetiformis without any abnormal biological findings. She was placed on oral corticosteroid therapy, prednisolone 60 mg tapered to 5 mg and a topical corticosteroid preparation, with partial remission after parturition. Note that the patient had Fitzpatrick skin type III and had no personal history of psoriasis, no notion of taking oral contraceptives, and no history of prior medications or known endocrinopathies.

The patient was admitted five months post-partum with a similar clinical presentation, with the appearance of new lesions. Erythematous-squamous plaques with an annular arrangement bordered by white, milky, non-follicular pustules at the periphery were observed. These lesions evolved in a centrifugal pattern and predominated on the folds, abdomen, back, thighs, arms, forearms, and legs, while sparing the face, scalp and palmoplantar region, with the presence of satellite lesions consisting of non-follicular pustules on an erythematous background (Figs. 1a and 1b).

Figures 1: (a and b) Clinical presentation of pustular psoriasis of pregnancy.

An examination of the fingernails revealed a thimble-like pattern. The mucous membranes were examined without any particularities.

In addition, she showed no bullae or post-bullous erosions and reported no arthralgia or digestive or respiratory signs. The clinical features occurred in the context of apyrexia and preservation of general condition.

Dermoscopy revealed confluent milky-white pustules on an erythematous base (Fig. 2).

Figure 2: Dermoscopy revealing confluent, milky-white pustules on an erythematous base.

Our approach was to perform a laboratory examination. The results showed a normal complete blood count, normal calcium levels, and CRP elevated to 67 mg/dL. The thyroid panel, liver, lipid, renal, and glycemic panel, and protein levels were normal.

A skin biopsy was performed and showed an epithelial lining bordered by an epidermis of variable thickness. It showed the foci of psoriasiform hyperplasia surmounted by a thin layer of orthokeratosis with focal foci of parakeratosis. The granular layer was severely reduced. There was an exocytosis of neutrophilic granulocytes with intracorneal pustules and moderate spongiosis. The superficial reticular dermis was highly edematous. Vessels were present, surrounded by a discrete, predominantly mononuclear inflammatory infiltrate. Skin annexes were regular (Fig. 3).

Figure 3: Histological aspect revealed in a skin biopsy punch 4 mm (H&E; 20x).

The results from the immunohistochemistry tests for anti-IgA, anti-IgG, anti-IgM, and anti-C3 antibodies were all negative. The bacteriological sampling of pustules was sterile. Based on these findings, the diagnosis of pustular psoriasis of pregnancy that persisted in the postpartum period was accepted. The patient was then started on a regimen of acitretin 25 mg daily, associated with phototherapy consisting of narrow-band UVB sessions delivered three times a week, with a total of 20 sessions, and skincare with superfatted gel and repair creams.

The patient’s condition improved significantly, with a complete resolution of the lesions observed after two months of treatment. No new lesions emerged after three months of therapy (Figs. 4a and 4b).

Figures 4: (a and b) Clinical images after three months of treatment.

DISCUSSION

Pustular psoriasis of pregnancy, or impetigo herpetiformis (IH), first described by Hebra in 1872, is a rare gestational dermatosis, occurring mainly during the third trimester of pregnancy and generally disappearing after delivery. However, there is a possibility of recurrence in subsequent pregnancies. Generally, the recurrence of pustular psoriasis of pregnancy is characterized by a more severe natural course and an earlier onset in subsequent pregnancies [1].

Recurrences may also occur in the postpartum period, as indicated by this case report of herpetiform impetigo occurring in the postpartum period and triggered by secondary hypoparathyroidism [2]. In our case, she developed two episodes of pustulosis, one in each pregnancy. The second episode was more severe than the first, with a complete remission after the first delivery, yet a partial remission after the second delivery and then a reappearance of symptoms five months later in the postpartum period.

Considering the clinical, histological, and pathogenic concordance with psoriasis, several authors consider that this condition is a variant of pustular psoriasis precipitated by an unusual metabolic state such as hormonal variations (pregnancy and oral contraception), infections, hypocalcemia, menstruation, or even stress [3,4].

However, for other authors, the absence of a personal or family history of psoriasis, healing after childbirth, and reappearance in the event of a new pregnancy means that impetigo herpetiformis is a separate entity [5].

The pathogenesis of pustular psoriasis of pregnancy remains poorly elucidated. However, hypocalcemia, thyroid disorder [6], hypoalbuminemia [7], low levels of vitamin D [8], infection, oral contraceptives, and menstruation [9] have been incriminated in the onset of the disease.

Several medications could also induce it. In one report, the pustular psoriasis of pregnancy was triggered by N-Butylscopolamine bromide [10], which developed during the 34^th week of gestation after five days’ ingestion of the drug.

Our patient was not taking oral contraceptives or other medications that could induce HI, and the menstrual period did not trigger episodes of pustulosis. The examination conducted on admission revealed normal levels of calcium and thyroid hormones in the blood.

Pustular psoriasis of pregnancy manifests mainly as a pustular eruption that begins symmetrically in the flexural and fold areas and then spreads centrifugally.

The lesions are annular erythematous plaques bordered by sterile pustules. They form plaques and pustules that erode and then crust over. Generalized eruption and even exfoliation of the entire body may occur, as occurred in our patient. Mucous membranes are rarely affected.

This condition is generally associated with systemic symptoms such as fever, sweating, tachycardia, nausea, diarrhea, vomiting, lymphadenopathy, splenomegaly, and tetany. In severe cases, renal or cardiac failure may occur [11].

In addition, pustular psoriasis of pregnancy is associated with an increased incidence of gestational hypertension, congenital anomalies and placental insufficiency leading to an increased risk of premature membrane rupture, intrauterine growth retardation, prematurity, hypotrophy, hydrocephalus and intracranial hypertension, intrauterine fetal demise, and neonatal death [12].

The histological pathology is similar to that of generalized pustular psoriasis. The spongy pustules contain neutrophils that have migrated from the papillary dermis to the epidermis. As the pustule enlarges, the epidermal cells undergo cytolysis. In the papillary dermis, infiltrates of lymphocytes and neutrophils are observed, and direct immunofluorescence is negative.

Although numerous treatment options have been proposed for pustular psoriasis of pregnancy, there are no specific guidelines, and the evidence of efficacy is weak.

Therapeutic management is poorly standardized, and the cases reported in the literature call for oral corticosteroid therapy, Cyclosporine at a dose of 2 to 7.5 mg/kg/day, retinoids, methotrexate, phototherapy, biotherapy, antibiotics, and symptomatic treatments [11,13–15]. Symptomatic treatment calls for calcium and vitamin D supplementation if hypocalcemia is present, as well as fluid and electrolyte rebalancing, protein supplementation, and nursing care.

CONCLUSION

Pustular psoriasis of pregnancy is a rare dermatosis of pregnant women. The pathogenesis of this condition remains poorly elucidated. It constitutes a diagnostic and therapeutic emergency, and there is yet no codified treatment for this condition. However, several therapeutic strategies have demonstrated their efficacy, notably phototherapy and acitretin, which may be used postpartum. However, there are several disadvantages to this approach, including the contraindication with breastfeeding and the need for effective contraception.