Dermatoses of pregnancy




19: Dermatoses of pregnancy


Jeff Shornick


Abstract:



Although many dermatologic conditions are affected by pregnancy, there are four predominant dermatoses that are unique to pregnancy. These are pemphigoid gestationis, polymorphic eruption of pregnancy, atopic eruption of pregnancy, and intrahepatic cholestasis of pregnancy. This chapter will review those dermatoses and their relevant mimickers.

Key terms:


pemphigoid gestationis


polymorphic eruption of pregnancy


atopic eruption of pregnancy


intrahepatic cholestasis of pregnancy


dermatoses of pregnancy


pregnancy



Introduction


There are four accepted entities included in the dermatoses of pregnancy. They are pemphigoid gestationis (PG; also known as “herpes gestationis” or “gestational pemphigoid”); polymorphic eruption of pregnancy (PEP; also known as “pruritic urticarial papules and plaques of pregnancy” or “PUPPP”); atopic eruption of pregnancy (AEP); and intrahepatic cholestasis of pregnancy (ICP; also known as “obstetric cholestasis” or “jaundice of pregnancy”).


Nomenclature in this group is somewhat confusing because names and nomenclature have changed as understanding has evolved. Disagreement persists as to whether additional entities should be added (e.g., pustular psoriasis associated with pregnancy) or whether a given entity should be carved out as distinctive (e.g., whether or not pruritic folliculitis of pregnancy should be lumped into AEP). The best way to think about dermatoses of pregnancy is that PG, PEP, and cholestasis are all sufficiently defined to be clearly recognizable (although PEP awaits a defining biomarker), and AEP stands for everything else.


Such a classification admittedly leaves room for improvement, but that will not happen until we have a clearer understanding of mechanisms.


It is more likely that an itchy pregnant woman has something unrelated to pregnancy, such as scabies, than a specific dermatosis of pregnancy. Therefore the first differential step is always to decide whether the pregnancy is causative or coincidental.


Nearly all articles on the specific dermatoses of pregnancy include ICP, which is not really a dermatosis. ICP presents with pruritus and excoriations, but it is not really a specific dermatosis. ICP is included in the dermatoses of pregnancy because patients present with pruritus and a rash, but to the dermatologist’s eye, the rash is entirely secondary.


Some skin diseases may be worse during pregnancy (such as psoriasis and eczema herpeticum), but these are not considered among the dermatoses of pregnancy. Preexisting diseases that can be made better or worse by pregnancy are also not considered to be dermatoses of pregnancy.


Pemphigoid gestationis


Clinical features


PG is the most clinically distinct and histopathologically defined of the dermatoses of pregnancy. For patients with rash, PG is the diagnosis to exclude.




Work-up


Referral to a dermatologist should be considered for work-up and treatment. A skin biopsy should be done for routine pathology and DIF.



Indirect immunofluorescence (IIF) is less reliable; however, ELISA for NC16A (BP180) is detectable in over 90% of cases, offering a reliable alternative to biopsy. Antibody titers do not correlate with the degree of skin involvement.


Antithyroid antibodies are increased, although their clinical relevance is unclear. Most patients are clinically euthyroid. On the other hand, the risk for subsequent autoimmune thyroid disease, especially Graves disease, is clearly increased in those with a history of PG, affecting about 10% of patients.


Differential diagnosis


The primary differential in PG is between PEP and a wide variety of diseases unrelated to pregnancy. Immunofluorescence or ELISA is the key to differentiating PG. Most typically, the relentless progression of unbearable itch associated with urticarial lesions, rapidly progressing to clustered, tense blisters, is characteristic of PG.


Initial steps in management


PG is rare; treatment guidelines are driven by expert opinion.


Because PG is not associated with significant maternal or fetal risk and because it tends to remit spontaneously postpartum, it is imperative not to create disproportionate risk from therapy.


Jul 22, 2021 | Posted by in Dermatology | Comments Off on Dermatoses of pregnancy
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