Diagnosis: Sweet's Syndrome
Description: Tender red nodules on the knee
Clinical Features: Nodule
Pathology/Site Features: Knee
Sex: F
Age: 54
Submitted By: Ian McColl
Differential DiagnosisHistory:
This lady has clinically florid Sweet's Syndrome on her legs, arms and in an old pneumothorax scar on her right chest wall.
This has only come up in the last few days. She clinically had painful legs and fever and features of a viral infection for a couple of days before the rash actually appeared. You have done a variety of blood tests looking for various viruses and I note that it showed she has had pre-existing glandular fever and herpes simplex but nothing else of note. Her blood count does not show any evidence of underlying leukaemias although she does have a mild neutrophilia.
Sweet's Syndrome or acute neutrophilic dermatosis was first described by an English dermatologist some years ago. It is a reaction pattern in the skin to a variety of causes including drugs, infections and particularly underlying leukaemias or myeloid disorders including myeloma.
I have organised some other screening blood tests today, copies of which will come to you, to try and exclude some of these diseases. She has had a bit of diarrhoea recently but nothing to suggest Crohn's Disease or ulcerative colitis.
I have put her on some oral steroids 50 mg daily for 5 days, cutting in half to 25 for 5 days, then 12.5 mgs for 5 days then we cease. This should get rid of the pain and swelling very quickly and make her more comfortable for Christmas. I would like to see her once I come back from the Christmas break and see if we can nail down a cause for this. Occasionally Sweet's Syndrome will pre-date the myeloid disorder, although this type usually presents as a bullous eruption on the back of the hands or elsewhere.
Interestingly it showed features of vasculitis.This used to be a feature against a diagnosis of Sweets syndrome but see the following reference.
Vascular inflammation (vasculitis) in Sweet syndrome: a clinicopathologic study of 28 biopsy specimens from 21 patients.
Malone JC, Slone SP, Wills-Frank LA, Fearneyhough PK, Lear SC, Goldsmith LJ, Hood AF, Callen JP.