Are You Confident of the Diagnosis?
Prurigo of pregnancy (PP) is the most contested classification of the pregnancy dermatoses. The features of this disorder have historically been ill-defined. Its current classification includes papular dermatitis and pruritic folliculitis, which are considered by some to be separate disease processes.
It is postulated that prurigo of pregnancy is actually the result of pruritus gravidarum occurring in atopic women, and it has also been speculated that most of these patients simply have atopic dermatitis. Nevertheless, unless a clear alternative etiology can be elucidated, patients with typical clinical features are generally given the diagnosis of prurigo of pregnancy.
What you should be alert for in the history
Patients with PP typically report an earlier appearance of symptoms than those with other pregnancy dermatoses, with onset usually occurring around 25-30 weeks of gestation.
Characteristic features on physical examination
PP is characterized by discrete, extremely pruritic erythematous or skin-colored papules that occur predominately on the extensor surfaces and result in excoriated lesions (Figure 1, Figure 2). Lesions are small and may be follicular or pustular. In addition to the extensor surfaces of the extremities, lesions may also occur on the trunk. PP usually resolves after parturition but may persist for months postpartum. It may recur in subsequent pregnancies, although this is reportedly rare.
The differential diagnosis includes scabies.
Who is at Risk for Developing this Disease?
Preexisting atopic dermatitis may increase the likelihood of occurring, but any gravid female may develop PP.
What is the Cause of the Disease?
The pathogenesis of this disorder is unknown. Some consider PP to be the manifestation of pruritus gravidarum in atopic women.
It is theorized that change in maternal immunologic milieu is the initiating factor in PP. To accommodate antigenically different tissues in the gravid state and prevent fetal rejection, a shift occurs favoring the T-helper 2 (Th2) humoral response as opposed to the cell-mediated immune function of T-helper 1 (Th1). Th2 cytokine profile of pregnancy favors the exacerbation and appearance of atopic dermatitis and pruritus, a Th2 dominant disease.
Systemic Implications and Complications
Most patients will benefit from topical corticosteroids and oral antihistamines. Conditioning the skin with moisturizers is also helpful.
Optimal Therapeutic Approach for this Disease
If the patient presentation is classic, then manage the patient symptomatically, as there is no increased risk to the mother or fetus. Mid-potent topical corticosteroids should relieve pruritus. Insomnia secondary to pruritus is common and, therefore, oral antihistamines in conjunction with topical therapy is recommended. Specific recommendations include diphendyramine 25-50mg nightly as needed and Triamcinolone 0.1% cream twice daily up to 4 weeks.
If primary lesions are not detected on the skin or are in question, then drawing total serum or urine bile acids is recommended. Bile acids may range from 3-100 times normal levels if patients have underlying intrahepatic cholestasis of pregnancy. Addionally, for recalcitrant and intense pruritus, light therapy with narrowband ultraviolet light B two to three times per week can be offered.
Unusual Clinical Scenarios to Consider in Patient Management
The presence of primary lesions such as papules and/or pustules rules out intrahepatic cholestasis of pregnancy. As scabies is in the differential diagnosis, inquire about involvement of the dermatosis in close contacts, examine the web spaces of the hands and intertriginous areas for papules and burrows.
What is the Evidence?
Holmes, RC, Black, MM. “The specific dermatoses of pregnancy”. J Am Acad Dermatol. vol. 8. 1983. pp. 405-12. (This article that defines the various catergories of skin lesions occurring in pregnancy.)
Al-Fares, SI, Vaughan Jones, SA, Black, MM. “The specific dermatoses of pregnancy: a re-appraisal”. JEADY. vol. 15. 2001. pp. 197-206. (This article clarifies specific guidelines for diagnosing the dermatoses of pregnancy.)
Ambros-Rudolph, CM, Mullegger, RR, Vaughan Jones, SA, Kerl, H, Black, MM. “The specific dermatoses of pregnancy revisited and reclassified: Results of a retrospective two-center study on 505 pregnant patients”. J Am Acad Dermatol. vol. 54. 2006. pp. 395-404. (This article clarifies specific guidelines for diagnosing the dermatoses of pregnancy.)
Hayashi, R. “Bullous dermatoses and prurigo of pregnancy”. Clin Obstet Gynecol. vol. 33. 1990. pp. 746-53. (This article defines and describes the bullous versus the other pruritic dermatoses of pregnancy.)
Bremmer, M, Driscoll, MS, Colgan, R. “Six skin disorders of pregnancy: a management guide”. OBG Management. vol. 22. 2010. pp. 24-33. (This article is a brief summary for the nondermatologist of the main dermatoses of pregnancy with a user-friendly table that aids in sorting the diagostic clues and treatment pearls.)
Vaughan Jones, SA, Hern, S, Nelson-Piercy, C, Seed, PT, Black, MM. “A prospective study of 200 women with dermatoses of pregnancy correlating clinical findings with hormonal and immunopathological profiles”. Br J Dermatol. vol. 141. 1999. pp. 71-81. (This article clarifies specific lab and pathology diagnostic clues for diagnosing the dermatoses of pregnancy.)
Copyright © 2017, 2013 Decision Support in Medicine, LLC. All rights reserved.
No sponsor or advertiser has participated in, approved or paid for the content provided by Decision Support in Medicine LLC. The Licensed Content is the property of and copyrighted by DSM.