A Clinician's Pearls and Myths in Rheumatology by John H. Stone

Author:John H. Stone
Language: eng
Format: epub
Publisher: Springer London, London

Autoinflammatory diseases

Behçet's syndrome

Age group affected

Pediatric

Adult

Areas of highest prevalence

Mostly Europe and North America

Silk Route

Monogenic heritability

Yes

No

Relapsing fever

Very common

Very rare

Disease course

Relentless unless treated

Abates in time

Particular links have been drawn between Behçet's syndrome and the hyper IgD syndrome (Sakane et al. 1999). In fact, IgD levels are not elevated in Behçet's syndrome (Brezniak et al. 1998).

Myth: All clinical manifestations of Behçet's syndrome are caused by vasculitis.

Reality: Many Behçet's syndrome lesions are associated with perivascular inflammation in the absence of true vascular wall destruction. Examples of such manifestations are the oral ulcers, genital lesions, and brain findings (Hirohata 2008). Acne lesions and their associated pustules have also been considered to represent cutaneous vasculitis, but it is now known that they are indistinguishable histo-pathologically from acne vulgaris (Ergun et al. 1998).

Tissue biopsies in Behçet's syndrome generally yield no pathological findings that are pathognomonic of that condition. Clinicians must bear in mind that unless there are compelling reasons for biopsy to exclude other disorders, the diagnosis of Behçet's syndrome usually rests upon its clinical features alone.

Myth: The pustules of Behçet's syndrome are sterile.

Reality: Bacteria are present in the cultures of pustules in Behçet's syndrome patients, just as they are in acne vulgaris (Hatemi et al. 2004). However, the bacteriology of Behçet's syndrome differs from that of acne vulgaris. Staphylococcus aureus, common in the lesions of Behçet's syndrome, is unusual in acne vulgaris.

Knowledge of the bacteriology of non-pustular lesions in Behçet's syndrome remains poorly described. Impairments of innate immunity may explain some of the findings within the acne pustules associated with Behçet's syndrome, including Staphylococcus aureus growth. One piece of evidence supporting defects in innate immunity is the fact that decreased mannose binding lectin levels (MBL) correlate with more severe Behçet's syndrome (Inanc et al. 2005). MBL plays an important role in complement activation and the opsonization of pathogens. Deficiency in this molecule heightens a person's susceptibility to infection.

Myth: The diagnosis of Behçet's syndrome is untenable without a history of oral ulcers.

Reality: Oral ulcers are often viewed as a sine qua non of Behçet's syndrome. Although oral ulcers occur in the overwhelming majority of Behçet's patients, there is a small subset that has classic disease features in every other way but do not manifest oral ulcers.

During the development of the International Study Group's 1990 classification criteria (International Study Group 1990), 28 such patients were identified among the 914 patients included in the study. Thus, 3% of patients diagnosed by Behçet's syndrome experts as having that disorder did not have oral ulcers. At times, some of those patients developed the classic oral lesions, but others remained ulcer-free even as other manifestations of Behçet's syndrome persisted or recurred.

Myth: Tender red lesions that occur on the lower extremities in Behçet's syndrome are inevitably erythema nodosum.

Reality: Erythema nodosum (EN), a septal panniculitis, does occur in Behçet's syndrome and presents as it does in other conditions with tender, nodular lesions. However, the EN of Behçet's syndrome bears some important differences to that observed, for example, in sarcoidosis and inflammatory bowel disease. The following

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