Case Presentation: Our patient is a 30 year old man with no significant medical history who presented with 4-day history of a diffuse painful erythematous nodular rash that started on his right knee and then spread diffusely to both lower and upper extremities sparing palms, soles, and trunk. About twenty-four later patient developed a petechial rash in both knees and severe arthralgias that affected both ankles and metacarpophalangeal with limited ambulation (Figure 1). He relayed that two weeks prior to this rash starting he had “flu-like” symptoms, generalized body ache, 2 episodes of watery, non-bloody diarrhea, dark urine and a subjective fevers. The day prior to presentation he took acetaminophen and ibuprofen for the arthralgias with no improvement of his symptoms. Initial laboratory test showed white blood count 37.8 K/uL, neutrophils 83%, Erythrocyte sedimentation rate 82 mm/hr, C-reactive protein 432.16 mg/L, creatinine elevated to 1.22 mg/dL from a baseline of 0.7 mg/dL, immunofixation revealed polyclonal gammopathy pattern, with elevated Ig A and Ig G, ALT 257 U/L AST 187 U/L. ANCA and ANA were negative. Complement levels were normal. The urinalysis showed white cells 47, RBC 2 and proteins 30. Dysmorphic RBC, multiple cellular and hyaline casts were seen in the urine sediment (Figure 2). Skin biopsy showed atypical subcutaneous neutrophilic dermatosis consistent with Sweet syndrome. Patient was started on Prednisone 40mg/day with improvement of pain and rash.

Discussion: Sweet syndrome, acute febrile neutrophilic dermatosis, is an uncommon severe dermatologic disorder. It presents with an abrupt onset of tender skin plaques or nodules, fever and arthralgias and rarely involves other organs. There are four categories: Idiopathic (the most common), Para-inflammatory, Paraneoplastic, and Pregnancy-associated. Idiopathic Sweet syndrome has been associated with upper respiratory infections such as in our patient. Renal involvement in Sweet Syndrome is uncommon, with only 4 case reports in the literature. . Renal involvement features proteinuria and acute kidney injury (AKI) with one case also having hematuria. Kidney biopsies have shown mesangial glomerulonephritis and interstitial nephritis. One of the cases showed sterile nodular abscesses on CT scan. Steroid therapy induced complete resolution of proteinuria and restoration of normal kidney function in two patients; while the others were reported to require dialysis without recovery of renal function.

Conclusions: While we were unable to obtain a kidney biopsy to confirm our diagnosis of sweet syndrome within the renal parenchyma, his clinical response of resolution of his AKI on steroids with the features of active urinary sediment, dysmorphic RBCs and cellular cast is highly consistent with his having Sweets syndrome with renal involvement. Identification of extracutaneous manifestations of Sweet syndrome and early instauration of treatment is important to prevent irreversible organ damage.

IMAGE 1: Figure 1. Erythematous nodular rash

IMAGE 2: Figure 2. Urine sediment