Vasculitis Syndromes

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Chapter 161 Vasculitis Syndromes

Childhood vasculitis encompasses a broad spectrum of diseases that share a common denominator, inflammation of the blood vessels. The pathogenesis of the vasculitides is generally idiopathic; some forms of vasculitis are associated with infectious agents and medications, and others may occur in the setting of preexisting autoimmune disease. The pattern of vessel injury provides insight into the form of vasculitis and serves as a framework to delineate the different vasculitic syndromes. The distribution of vascular injury includes small vessels (capillaries, arterioles, and postcapillary venules), medium vessels (renal arteries, mesenteric vasculature, and coronary arteries), and large vessels (the aorta and its proximal branches). Additionally, some forms of small vessel vasculitis are characterized by the presence of antineutrophil cytoplasmic antibodies (ANCAs), whereas others are associated with immune complex deposition in affected tissues. A combination of clinical features, histologic appearance of involved vessels, and laboratory data is utilized to classify vasculitis (Tables 161-1 to 161-3).

Childhood vasculitis varies from a relatively benign and self-limited disease such as Henoch-Schönlein purpura to catastrophic disease with end-organ damage as seen in Wegener granulomatosis. Vasculitis generally manifests as a heterogeneous multisystem disease. Although some features, such as purpura, are easily identifiable, others, such as hypertension secondary to renal artery occlusion or glomerulonephritis, can be more subtle. Ultimately, the key to recognizing vasculitis relies heavily on pattern recognition. Demonstration of vessel injury and inflammation on biopsy or vascular imaging is required to confirm a diagnosis of vasculitis.

161.1 Henoch-Schönlein Purpura

Henoch-Schönlein purpura (HSP) is the most common vasculitis of childhood and is characterized by leukocytoclastic vasculitis and immunoglobulin (Ig) A deposition in the small vessels in the skin, joints, gastrointestinal tract, and kidney.

Clinical Manifestations

The hallmark of HSP is its rash: palpable purpura starting as pink macules or wheals and developing into petechiae, raised purpura, or larger ecchymoses. Occasionally, bullae and ulcerations develop. The skin lesions are usually symmetric and occur in gravity-dependent areas (lower extremities) or on pressure points (buttocks) (Figs. 161-1 and 161-2). The skin lesions often evolve in groups, typically lasting 3-10 days, and may recur up to 4 mo after initial presentation. Subcutaneous edema localized to the dorsa of hands and feet, periorbital area, lips, scrotum, or scalp is also common.

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Figure 161-2 Henoch-Schönlein purpura.

(From Korting GW: Hautkrankheiten bei Kindern und Jungendlichen, ed 3, Stuttgart, 1982, FK Schattaur Verlag.)

Musculoskeletal involvement, including arthritis and arthralgias, is common, occurring in up to 75% of children with HSP. The arthritis tends to be self-limited and oligoarticular, with a predilection for the lower extremities, and does not lead to deformities. The arthritis usually resolves within 2 wk but can recur.

Gastrointestinal manifestations of HSP occur in up to 80% of children with HSP. They include abdominal pain, vomiting, diarrhea, paralytic ileus, melena, intussusception, and mesenteric ischemia or perforation. Endoscopic evaluation is usually not needed but may identify purpura of the intestinal tract.

Renal involvement occurs in up to 50% of children with HSP, manifesting as hematuria, proteinuria, hypertension, frank nephritis, nephrotic syndrome, and acute or chronic renal failure. Progression to end-stage renal disease is uncommon in children (1-2%) (see Chapter 509 for more detailed discussion of HSP renal disease).

Neurologic manifestations of HSP, due to hypertension or central nervous system (CNS) vasculitis, may also occur. They include intracerebral hemorrhage, seizures, headaches, and behavior changes. Other less common potential manifestations of HSP are orchitis, carditis, inflammatory eye disease, testicular torsion, and pulmonary hemorrhage.

Diagnosis

The diagnosis of HSP is a clinical one and is often straightforward when the typical rash is present. However, in at least 25% of cases, the rash appears after other manifestations, making early diagnosis challenging. Classification criteria for HSP are summarized in Table 161-4. The differential diagnosis for HSP depends on specific organ involvement but usually includes other small vessel vasculitides, infections, coagulopathies, and other acute intra-abdominal processes.

Acute hemorrhagic edema (AHE), an isolated cutaneous leukocytoclastic vasculitis that affects infants <2 yr of age, resembles HSP clinically. AHE manifests as fever; tender edema of the face, scrotum, hands, and feet; and ecchymosis (usually larger than the purpura of HSP) on the face and extremities (Fig. 161-3). The trunk is spared, but petechiae may be seen in mucous membranes. The patient usually appears well except for the rash. The platelet count is normal or elevated, and the urinalysis results are normal. The younger age, the nature of the lesions, absence of other organ involvement, and a biopsy may help distinguish AHE from HSP.

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Figure 161-3 Typical lesions of acute hemorrhagic edema on the arm of an infant.

(From Eichenfield LF, Frieden IJ, Esterly NB: Textbook of neonatal dermatology, Philadelphia, 2001, WB Saunders.)