Polymorphic eruption of pregnancy

A 29‐year‐old woman developed a pruritic papular eruption that appeared symmetrically on the lateral part of her arms and elbows and on the media part of her thighs and knees in the 35th week of gestation (Fig. 1). The papules were erythematous, firm, flat, with a slightly elevated border, and measured 2–5 mm in diameter. A few papules quickly coalesced to form urticarial plaques. There were no lesions on the abdomen. In the 40th week of gestation, she delivered a healthy girl and a week later the eruption cleared up spontaneously. Two years later, in the 37th week of gestation of her second pregnancy, the same patient developed an itchy papular eruption, clinically comparable with that of the previous pregnancy, which spontaneously disappeared a few days after delivery of a healthy boy. During both pregnancies routine laboratory investigations, hormonal tests, and tests to detect cholestasis and viral hepatitis (A,B,C) were performed. A biopsy of lesional and perilesional skin was taken for histologic and direct immunofluorescence (DIF) examination. Serum was tested by indirect Immunofluorescence (IIF) staining for IgG, IgM, and IgA, and by a complement fixation test. For histologic examination, biopsy specimens were fixed in 10% buffered formalin, embedded in paraffin, sectioned at 5 μm, and stained with hematoxylin and eosin. Direct immunofluorescence was performed on cryostat sections from biopsy specimens, washed in phosphate‐buffered saline (PBS) and incubated with fluorescein isothiocyanate (FITC) labeled antibodies (anti‐IgG, IgA, IgM, C3, fibrinogen) (DAKO, Glostrup, Denmark). The slides were mounted in buffered glycerol and examined by fluorescent microscopy. An immunohistochemical study was also performed on cryostat sections using the alkaline phosphatase antialkaline phosphatase (APAAP) technique with monoclonal antibodies (anti‐CD45RO, CD3, CD4, CD8, CD25, CD22, CD1a, HLA‐DR, CD54). The results of routine laboratory and hormonal tests and tests for cholestasis and viral hepatitis (A,B,C) were normal or negative. The histopathologic examination of a papule showed mild spongiosis in the epidermis, slight oedema, and a moderate perivascular infiltrate of lymphocytes and monocytes in the superficial dermis (Fig. 2). Examination by DIF on lesional skin showed a dense granular‐linear deposit of IgM and C3 along the basement membrane zone (BMZ) of the epidermis and hair follicles (Fig. 3). After healing of the dermatosis, repeated DIF near the previously examined location was negative. An IIF study revealed no circulating anti‐BMZ IgG, IgM, or IgA autoantibodies. The complement fixation test was also negative. The immunohistochemical study showed a perivascular infiltrate in the dermis consisting mainly of T lymphocytes (CD4+, DRH+, CD25+).