Pruritic folliculitis of pregnancy

Did You Know?

• Pruritic folliculitis of pregnancy is classified under atopic eruption of pregnancy (AEP), which also includes eczema and prurigo of pregnancy.
• The condition is diagnosed by biopsy showing sterile pustules with inflammatory cells and no bacteria or microorganisms.
• Symptoms are typically mildly pruritic or asymptomatic and last from one week to several months, resolving within one month after birth.

History

The condition was first observed in six pregnant individuals in 1981, with papules appearing at various times during the second to third trimester. Biopsies taken over a 15-month period, stained with hematoxylin and eosin, revealed inflammatory cells including neutrophils, monocytes, lymphocytes, and eosinophils. Immunofluorescence microscopy in four samples showed no immunoglobulins (IgG, IgM, IgA) or C3. Few case reports followed, indicating its rarity. A prospective study in 1994 by Roger et al. found one case among 3,192 pregnant women, a rate of 0.03%.

Pathophysiology

Folliculitis generally involves inflammation of hair follicles due to infection or damage from bacteria, fungi, viruses, or ingrown hairs. Pruritic folliculitis of pregnancy differs by occurring only in pregnant women during the second or third trimester, with no clear mechanism established. Proposed causes include hormonal imbalance or immunological changes, such as a reduction in T helper 1 cells and an increase in T helper 2 cells during pregnancy, but evidence is insufficient. Suspected risk factors include dry skin, genetics affecting hormone production, poor personal hygiene, family history of pruritus in pregnancy, family history of eczema, hay fever, or asthma, and pruritus while taking contraceptive pills before pregnancy. The condition resolves after pregnancy and has no significant link to harm for mother or baby.

Management and treatment

No official treatment guidelines exist due to the unknown etiology, so management focuses on symptom relief without harming mother or fetus. Non-pharmacological interventions are recommended first, including loose-fitting clothes, emollients, warm baths, avoiding harsh soaps, and maintaining good hygiene. If itching persists, low to mid potency topical corticosteroids, first-generation antihistamines (e.g., diphenhydramine or chlorpheniramine), 10% topical benzoyl peroxide, 1% topical hydrocortisone, or a short course of systemic corticosteroids such as prednisone may be used. Narrowband ultraviolet B phototherapy has been explored as a novel option in one case study, but further investigation into its efficacy and safety is needed. A literature review from 1990–2005 found no associated morbidity for mother or fetus, and the condition resolves after pregnancy.

Clinical studies and case reports

A case report described a 30-year-old woman in her tenth week of a second pregnancy with widespread papulopustular follicular eruption mainly on her limbs. After initial treatment for bacterial folliculitis provided partial relief, histopathology confirmed sterile folliculitis with immune cells. She began narrowband UVB phototherapy at 70% of the minimal erythemal dose with 20% increments three times weekly at 11 weeks; her skin greatly improved after 10 treatments and completely resolved after 20, with no recurrence. A 26-year-old woman at 31 weeks with pustules over her upper torso, especially around the linea nigra, was treated with 5% topical benzoyl peroxide gel; the folliculitis cleared one week after delivery.