Sweet syndrome in the second trimester of pregnancy: a case report

Abstract Background First reported by Robert Douglas Sweet, acute febrile neutrophilic dermatosis, or Sweet syndrome, is a rare inflammatory skin disease [1] . Its typical manifestations consist of tender erythematous skin plaques, fever and elevated neutrophil counts in peripheral blood. Gestational Sweet syndrome (PASS) is an infrequent obstetric‑dermatological condition, and clinical onsets limited to the second trimester remain extremely rare [4,5]. Pregnant patients admitted for fever and cutaneous eruptions are usually suspected to suffer from infectious processes. This diagnostic bias frequently results in misclassification of PASS as cellulitis or sepsis, which brings about diagnostic delays and unnecessary antibiotic exposure for gravidas [6] . This paper describes a classic PASS episode emerging at 15 weeks of gestation in a patient without underlying chronic illnesses, highlighting diagnostic obstacles and positive clinical outcomes delivered through interdisciplinary collaboration between obstetric and dermatology teams. Case presentation A 40‑year‑old Han Chinese multiparous woman (G2P1) at 14⁺⁶ weeks of gestation presented with abrupt fever reaching up to 39.4 °C, together with chills, dizziness, general malaise and mild vomiting‑predominant gastrointestinal complaints. Cutaneous assessment detected extensive tender erythematous plaques covered with tiny pustules over the face, trunk and extremities. No mucosal damages were observed in either oral or ocular sites. Intravenous cefuroxime given as initial empirical therapy failed to suppress febrile episodes. Blood tests showed white blood cell counts of 14.99 × 10⁹/L with neutrophil proportion of 89.2 %, alongside significantly elevated high‑sensitivity C‑reactive protein(129.06 mg/L).Skin punch biopsy demonstrated epidermal hyperkeratosis, acanthosis, intra‑epidermal neutrophil infiltration and microabscess formation. Dermal layers presented mixed inflammatory cell infiltration including lymphocytes, neutrophils and histiocytes. Immunohistochemical assays returned positive CD15 and MPO staining, while CD34 and CD117 tests came out negative. After formal dermatological consultation, Sweet syndrome was confirmed. Daily intravenous methylprednisolone 60 mg was initiated. The patient’s fever subsided rapidly, and skin lesions gradually resolved within days. Treatment was then switched to oral methylprednisolone 28 mg daily following a pre‑planned tapering protocol. Both maternal physical status and fetal condition stayed stable throughout hospital admission and subsequent follow‑up. No recurrent fever or skin flare‑ups were noted. Conclusions When pregnant women develop fever, painful erythematous plaques and peripheral neutrophilia that show no response to anti‑infective treatment, clinicians ought to raise vigilance for Sweet syndrome. Early skin biopsy constitutes a vital tool to achieve definitive diagnosis and avoid prolonged unnecessary empirical antibiotic administration. Under joint monitoring by obstetricians and dermatologists, systemic glucocorticoids with appropriate starting doses and gradual dose reduction strategies can generate favourable maternal‑fetal clinical outcomes.