Exogenous factors have been implicated in the pathogenesis of ICP. There is a higher incidence of ICP during the winter. Low selenium levels have also been linked to ICP. This suggests that the environment and nutritional factors play a role.2
FIGURE 3
Excoriations down the legs
The differential Dx includes scabies
Itching has been reported to occur in 17% of pregnancies,2 so it is important to differentiate ICP from the conditions listed below.
- Pruritic urticarial papules and plaques of pregnancy—also known as polymorphic eruption of pregnancy—is a dermatosis of pregnancy. Unlike the excoriations of ICP, this condition involves papulovesicular or urticarial eruptions on the trunk and extremities. It is particularly pronounced around the abdominal striae, and is more common in nulliparous women.
- Pemphigoid gestationis, also known as herpes gestationis because of its appearance, is a bullous or blistering disease that is associated with pregnancy. It is often periumbilical and can also have target lesions, which are absent in ICP.
- Atopic eruption of pregnancy is a new term used to include previous non-specific diagnoses such as prurigo of pregnancy and pruritic folliculitis of pregnancy. Prurigo of pregnancy, which is also called Besnier’s prurigo gestationis, involves bite-like papules that resemble scabies. Pruritic folliculitis of pregnancy is characterized by red, follicle-based papules. These 2 conditions differ from ICP in that there is no cholestasis and liver studies are normal. (In ICP, there is an elevation in liver enzymes and serum bile acids.)
- Scabies infestation can occur during pregnancy. The mite burrows in the skin and produces severe itching between the fingers and in skin folds. Look for burrows and the typical distribution between the fingers, on the wrists, in the axilla, and around the waist. A positive scraping viewed under the microscope will show mites, eggs, and mite feces.