Case Presentation: A 21-year-old woman presented with pain and swelling of her right leg for the past 2 days. She noted that three weeks earlier, she fell off a jet ski in Miami and had some bruising to the area but no open wounds. On physical exam, her right anterior shin had a 3 cm area of erythema with edema but no bullae or pustule formation. Her labs were notable for a leukocytosis to 21.6 cells/uL with a left shift and CRP was normal at 0.4. Her serum beta-hcg was positive and she was estimated to be at 5 weeks gestation. She was placed on IV vancomycin for treatment of cellulitis. The patient’s pain, swelling, and erythema continued to worsen and she developed new fevers to 101 F with leukocytosis increased to 50 cells/uL and CRP to 24. Antibiotics were broadened to cover possible aquatic organisms. A CT of the lower extremity was obtained which showed concern for a developing collection. Incision and drainage was performed with copious amounts of pus which was sent for culture but was without growth. Her clinical course did not improve after this intervention. After I&D, the skin lesion progressed to resemble pyoderma gangrenosum. A punch biopsy was performed and showed near complete replacement of the dermis by neutrophilic inflammation, consistent with pyoderma gangrenosum. She also met clinical criteria of acute febrile neutrophilic dermatosis (sweet syndrome) and was felt to have an overlap of both. After discussion with maternal-fetal medicine, dermatology, and infectious disease, she was started on IV solumedrol 1 mg/kg twice daily with drastic improvement in fever curve, pain, and leukocytosis.
Discussion: Cellulitis is a common diagnosis encountered by hospitalists and in most cases improves with antibiotics. However, it is estimated that more than 10% of patients diagnosed with cellulitis have another process which makes knowledge of common differentials important (1). If there is concern for an atypical process or lack of improvement with antibiotics, a Dermatology consult and consideration of biopsy is recommended to evaluate for noninfectious alternative diagnoses (1). Sweet syndrome is a rare entity that consists of fever, leukocytosis, and erythematous nodules or plaques (2). It is usually associated with malignancy, medications, infections, or early pregnancy (2). The patient had a pyoderma gangrenosum/Sweet syndrome overlap given her clinical course was consistent with Sweet syndrome but her lesions were more consistent with pyoderma gangrenosum. Her presentation was attributed to her early pregnancy. Although these two conditions are very uncommon mimics of cellulitis, they should be considered when the clinical course worsens despite antibiotics.
Conclusions: Hospitalists should be vigilant about common mimics of cellulitis to prevent misdiagnosis which could lead to a prolonged hospital stay, readmissions, or significant morbidity. A dermatology consultation and discussion of biopsy should be considered if the clinical course worsens despite broad antibiotic coverage.