A case of sweet syndrome with spleen and lymph node involvement preceded by parvovirus B19 infection, and a review of the literature on extracutaneous sweet syndrome.

A 45-year-old white woman presented with fever, arthalgias, and widespread erythematous papules after a recent Parvovirus B19 infection. Biopsy findings were consistent with classic Sweet syndrome. A splenectomy, which was performed due to radiographic evidence of multiple splenic lesions, revealed a diffuse neutrophil-predominant infiltrate with formation of numerous "abcesses." Her skin lesions recurred several times over the next 6 years, with repeat biopsies showing evidence of recurrent Sweet neutrophilic dermatosis. The initial and recurrent skin eruptions were responsive to systemic steroids. A paratracheal lymph node biopsy was later performed to evaluate widespread lymphadenopathy, which showed complete effacement of nodal architecture by a mixed inflammatory and fibrotic process including neutrophils, with features reminiscent of cat-scratch disease. Special stains, tissue culture studies, and serologies were negative for an infectious etiology, and an extensive evaluation for hematologic or other malignancy was negative. This clinical-pathologic presentation was consistent with Sweet syndrome involving both cutaneous and lymphoreticular (spleen and lymph nodes) sites. This case illustrates the importance of recognizing extracutaneous involvement in Sweet syndrome and differentiating this from infectious, malignant, and other processes. The literature on extracutaneous involvement of Sweet syndrome is reviewed.