A Case of Pustular Psoriasis of Pregnancy With Positive Maternal-Fetal Outcomes

Comment

In our patient, the diagnosis of PPP was supported by the presence of erythematous, coalescent plaques with small pustules at the margins and central erosions as well as the histologic findings of subcorneal pustules with mild acanthosis of the epidermis with spongiosis and a sparse neutrophilic infiltrate into the dermis. Laboratory studies showing leukocytosis and an elevated ESR, which are often seen in PPP, also were noted.

The typical presentation of PPP is characterized by lesions that initially develop in skin folds with centrifugal spread.³ The lesions usually begin as erythematous plaques with a pustular ring with a central erosion. The face, palms, and soles of the feet typically are spared with occasional involvement of oral and esophageal mucosae. Biopsy findings typically include spongiform pustules with neutrophil invasion into the epidermis. Typical laboratory findings include electrolyte derangements with elevated ESR and leukocytosis.¹

Diagnosis of PPP is critical given the potential for associated fetal morbidity and mortality.⁴ Anticipatory guidance for the patient also is necessary, as PPP can recur with subsequent pregnancies or even use of oral contraceptive pills (OCPs). Notably, a patient with recurrences of PPP with each of 9 pregnancies also experienced a recurrence when taking a combination estrogen/progesterone OCP, but not with an estrogen-only diethylstilbestrol OCP.⁵ Although the pathophysiology is not entirely understood, the development of PPP is thought to be related to the hormonal changes that occur in the third trimester, most notably due to elevated progesterone levels.² The presence of progesterone in OCPs and recurrences associated with their use supports this altered hormonal state, contributing to the underlying pathophysiology of PPP.

Pustular psoriasis of pregnancy can occur in women without any personal or family history of psoriasis, and as such, it is unclear whether PPP is a separate entity or a hormonally induced variation of generalized pustular psoriasis. Recent evidence included reports of women with PPP who had a mutation in the IL-36 receptor antagonist, leading to a relative abundance of IL-36 inflammatory cytokines.⁶As the cytokine profile during pregnancy is physiologically altered to favor a T helper 2–cell state, the altered expression of cytokines is believed to trigger an inflammatory response conducive to the development of PPP.² This mutation in the IL-36 receptor antagonist also is found in individuals with generalized pustular psoriasis, suggesting an overlap of disease etiology related to these cytokine interactions.^2,7,8

The mainstay of treatment for PPP is oral corticosteroids. Cases of PPP that are unresponsive to systemic steroids have been documented, requiring treatment with cyclosporine.⁹ Antitumor necrosis factors also have been used safely during pregnancy.¹⁰ Narrowband UVB phototherapy also has been proposed as a treatment alternative for patients who do not respond to oral corticosteroids.¹¹

Conclusion

Pustular psoriasis of pregnancy is a rare dermatosis of pregnancy that, unlike most other common dermatoses of pregnancy, is associated with adverse fetal outcomes. Diagnosis and management of PPP are critical to ensure the best care and outcomes for the patient and fetus and for a successful delivery of a healthy neonate. Our patient with PPP presented with involvement of the body, palms, and oral mucosa in the absence of systemic symptoms. Close follow-up and comanagement with the patient’s obstetrician ensured safe outcomes for the patient and the neonate.