Monday, October 18, 2010

Classic papers: vasculitis

Every once in a while a paper comes out that’s so important it deserves a permanent place in the clinician’s library where it can be referred to and read in the original again and again. I’ve recently found two such classic papers in the field of rheumatology, published in Rheumatic Disease Clinics of North America. The two papers, published six years apart, have the same title, one being an update of the other: Vasculitis: a set of pearls and myths.

Here are a few from the two papers.

Pearl: Classic Polyarteritis Nodosa Spares the Lungs.

Pearl: Classic polyarteritis nodosa (PAN) is often a curable illness.

Myth: PAN is sometimes associated with ANCA.

Pearl: The Development of Mononeuritis Multiplex in the Absence of Diabetes Mellitus or Multiple Compression Injuries Strongly Suggests the Presence of Vasculitis.

Myth: Temporal Artery Biopsies Are Not Necessary in Some Cases, Because They Do Not Change Treatment. Starting corticosteroids without making every effort to confirm the diagnosis by biopsy is a sin that often comes home to roost only months later when the patient suffers side effects of corticosteroids and the next physician to evaluate him or her is left to wonder whether or not he or she ever really had GCA at all.

What does one do if the biopsy is negative but GCA still seems likely? In such cases, we recommend reviewing the biopsy with the pathologist to confirm the adequacy of the specimen and the negative reading. It is also important to ensure that a Congo red stain of the tissues was performed to exclude amyloid deposition, because amyloidosis may mimic GCA closely. One may also consider having a temporal artery biopsy performed on the contralateral side if both sides were not biopsied initially. Finally, if the biopsies are unequivocally not diagnostic of GCA but there is still a strong case for the disease on clinical grounds, treat the patient for GCA, fully assured that everything possible to confirm the diagnosis has been done.

Pearl: Aspirin is an important adjunct to glucocorticoids in the therapy of GCA. Two retrospective cohort studies demonstrated that a baby aspirin along with prednisone is more effective at preventing visual loss and cerebral ischemic events than is prednisone alone.

Pearl: Immunosuppressive Therapy Is Not Required for Most Cases of Henoch-Schonlein Purpura. Treatment with corticosteroids is recommended in the setting of critical organ involvement that does not seem to be self-limited.

Pearl: Henoch-Schonlein Purpura in the Adult May Present in the Same Fashion As Microscopic Polyangiitis. Although HSP is less common in adults than in children, it should always be considered in the differential diagnosis of vasculitis. HSP in adults may be initially misdiagnosed as MPA.

Pearl: The Churg-Strauss Syndrome Tends to Unfold in Three Stages. A prodromal phase characterized by allergic disease (typically asthma or allergic rhinitis), which may last from months to many years; an eosinophilia/tissue infiltration phase in which remarkably high peripheral eosinophilia may occur and tissue infiltration by eosinophils is observed in the lung, gastrointestinal tract, and other tissues; a vasculitic phase in which systemic vasculitis afflicts a wide range of organs, ranging from the heart and lungs to the peripheral nerves and skin.

Pearl: Churg-Strauss Syndrome Has a Striking Predilection for the Peripheral Nerves and Myocardium.

Myth: CSS is an ANCA-associated vasculitis. A substantial percentage of patients who have CSS—more than 50% in some studies—are ANCA-negative.

Myth: CSS is caused by the use of leukotriene inhibitors. This myth, approximately as old as leukotriene inhibitors themselves, is a classic case of confounding... The tapering of prednisone permitted by a leukotriene inhibitor eventually unmasks the underlying CSS.

Pearl: Scurvy can mimic ANCA-associated vasculitis, particularly MPA. Scurvy can cause perifollicular petechiae that mimic purpura, extensive gum inflammation, and alveolar hemorrhage, all of which could be confused with MPA. Think of scurvy when a severely malnourished patient is suspected of having an ANCA-associated vasculitis.

Pearl: Takayasu's Arteritis Is Included in the Differential Diagnosis of a Young Woman Presenting with Cardiomyopathy. The myocardium may also be involved in TA with histologic features of an inflammatory myocarditis.

Pearl: Headaches in Takayasu arteritis are bad news. Takayasu arteritis tends to cause bilateral subclavian artery stenoses and stenosis of the infrarenal aorta or narrowing of the large vessels to both lower extremities. Unfortunately, it can also cause renal artery stenosis , leading to renin-mediated hypertension.. .blood pressure measurements in the arms and even the legs do not provide accurate reflections of the central aortic pressure, which may become dangerously elevated. The patient who has Takayasu arteritis and intractable headaches requires a serum renin measurement, a thorough investigation of the circulation to all extremities, precise imaging of the renal arteries, and an accurate determination of the central aortic pressure.

Myth: Buerger's Disease Is a Disorder of Men. Although the classic Buerger's disease patient is a young male smoker in the fourth or fifth decade of life, … Women now comprise between 11% and 23% of all Buerger's disease cases.

Myth: Buerger disease is a systemic vasculitis. Buerger disease is characterized pathologically by a highly cellular thrombus with relative sparing of the blood vessel walls. Multinucleated giant cells can even be observed within the clot in Buerger disease. The architecture of the vascular wall is preserved, and there is no fibrinoid necrosis. The histopathologic findings in this disease provide significant insights into why systemic immunosuppressive therapy is relatively useless in Buerger disease.

Pearl: Buerger disease does not occur in only one limb. If called to see a patient who has intense ischemia in only one limb and no angiographic evidence of disease in other extremities, Buerger disease is not the diagnosis.

Myth: Buerger disease may present with Raynaud phenomenon. Buerger disease causes digital ischemia equaled by few other disorders, but it is not because of Raynaud phenomenon.

The two articles combined comprise about 100 pages of text. They are worth reading in their entirety. Study them and know vasculitis. Access the papers via MD Consult or ask your hospital librarian to get copies.

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