CASE #2: Neutrophilic dermatosis

Punch biopsy results showed a dense, diffuse neutrophilic infiltrate of the reticular dermis and pronounced papillary edema. The clinical picture and biopsy results were consistent with acute neutrophilic dermatosis, also known as Sweet’s syndrome, an unusual though by no means rare condition.

First described by Robert Sweet in 1964 and thought to be a reactive process triggered by any number of factors, this syndrome occurs most frequently in young women following a mild respiratory illness. Patients often feel ill and are febrile days to weeks prior to the appearance of the classically tender, round papules and nodules that coalesce to form plaques. Red to purple in color, these lesions usually appear on the patient’s face, neck, and upper extremities and are accompanied by peripheral and focal microscopic neutrophilia.5 Women with this type of Sweet’s syndrome outnumber men by a ratio of 15 to 1.6 Unless seen initially in dermatology, virtually all diagnoses of Sweet’s syndrome are delayed.

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More severe forms of Sweet’s syndrome—which are often atypical—can be triggered by cancer (especially hematopoietic malignancies) in about 15% to 20% of cases. Other triggers have been noted, including vaccinations and infections (primarily streptococcal, but also Yersinia and Salmonella).7 Crohn’s disease and ulcerative colitis can also trigger Sweet’s syndrome,8 as can such drugs as minocycline and sulfas. This condition has also been reported to be triggered by such diseases as lupus, rheumatoid arthritis, and Sjogren’s syndrome.5

Granulocyte colony stimulating factor has been shown to be a factor in the development of Sweet’s syndrome, as has an imbalance of type 1 T-helper cells.9

Clinically, major criteria for the diagnosis of this disease include the abrupt onset of painful lesions demonstrating a predominantly neutrophilic infiltrate. Biopsy results revealing the presence of leukocytoclastic vasculitis should throw a diagnosis of Sweet’s syndrome into doubt. Minor diagnostic criteria include precedent tumor, malignancy, infection, or vaccination; fever and/or malaise; and bloodwork showing erythrocyte sedimentation rate >20, positive C-reactive protein, bands on peripheral WBC >70% (Sweet’s syndrome can present with a normal peripheral WBC as well), and overall WBC >8,000/μL. The final classic minor criterion is a positive response to steroids or potassium iodide.

Even though at least half of Sweet’s syndrome cases are idiopathic,10 a diagnosis of this disease should prompt a search for an underlying condition or malignancy. This should include a complete blood count with peripheral smear to detect hematologic abnormalities; possible bone marrow aspiration; cultures of the lesions to detect fungal, viral, or bacterial agents; skin biopsy; and other related workup (e.g., colonoscopy) as indicated.

Skin biopsy helps distinguish Sweet’s syndrome from other such diagnostic considerations as granuloma annulare, erythema multiforme, erythema nodosum, herpes simplex, pyoderma gangrenosum, and drug eruptions.

Atypical Sweet’s syndrome bears enough resemblance to pyoderma gangrenosum that some have postulated that these two conditions may be the same disease. According to the prevailing argument, since both conditions frequently have the same appearance, a similar histologic picture, several triggers in common, and similar presenting symptoms, and since they respond to the same treatments, they may be identical diseases.

Standard treatment for Sweet’s syndrome is prednisone 1 mg/kg/day for four to six weeks. Treatment can be thwarted by the underlying condition that triggered the lesions. Other treatment choices in severe or nonresponsive cases included dapsone, cyclosporine, or one of the biologics. This patient was treated successfully with a three-month tapering dose of prednisone, starting at 80 mg/day.

Mr. Monroe is a physician assistant specializing in dermatology at Springer Clinic in Tulsa, Okla. He has no relationships to disclose relating to the contents of this article.


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All electronic documents accessed August 15, 2010.