A 39-year-old, previously healthy man presented to rheumatology clinic with 6 days of a progressively severe rash on his lower legs and pain in his knees and ankles. He denied recent upper respiratory or other infection. He took no medications. He was afebrile, and vital signs were normal. Physical examination revealed a rash on the feet and lower legs characterized by palpable purpura with several large areas of confluence (Figure 77-1). His knees were tender, and the ankles were tender and swollen; the remainder of the joint examination was unremarkable. The cardiopulmonary, abdominal, and neurologic examinations were normal. Laboratory values were remarkable for creatinine of 1.4 and a spot urine protein or creatinine ratio of 1.9. Chemistries, including liver functions, and a complete blood count (CBC) were normal. Antineutrophil cytoplasmic antibody (ANCA) studies were negative. A renal biopsy was performed and confirmed a diagnosis of Henoch-Schönlein purpura (HSP) (Figures 77-2 and 77-3).
A 39-year-old patient with Henoch-Schönlein purpura (HSP).
Renal biopsy in Henoch-Schönlein purpura (HSP). Light microscopy reveals a glomerular tuft with mesangial expansion and hypercellularity. Note the area of adhesion to Bowman capsule.
Renal biopsy in Henoch-Schönlein purpura (HSP). Immunofluorescence staining positive for immunoglobulin A (IgA) deposits in the mesangium.
The ANCA-negative small vessel vasculitis (SVV) have in common the pathogenic mechanism of immune-complex (IC) formation and deposition in and around small blood vessels, often with fixation of complement followed by varying degrees of inflammation. They also have in common almost universal cutaneous involvement that most frequently manifests clinically as palpable purpura and histologically as leukocytoclastic vasculitis. The clinical syndromes are distinguished by the nature of the immune complexes, epidemiology, and pattern of organ involvement (Table 77-1).
TABLE 77-1.Frequency of Organ Involvement During the Course of SVV (%) ||Download (.pdf) TABLE 77-1. Frequency of Organ Involvement During the Course of SVV (%)
|Disease ||Skin ||Musculoskeletal ||Renal ||GI ||Pulm ||Neuro ||Other |
|HSP ||100 ||Up to 84 ||20 to 50 ||50 ||Rare ||Very rare CNS involvement ||Scrotal pain and edema |
|Cryoglobulinemic vasculitis ||100 ||>70 ||35 to 60 in type II; less frequent in types I and III ||Liver function test (LFT) abnormalities common but related to HCV infection ||10 to 50 (may be subclinical) ||80 (almost exclusively PNS involvement) ||Raynaud and sicca symptoms |
|Hypersensitivity vasculitis ||100 ||Frequent ||Visceral involvement may occur but is rare and should prompt workup for other causes ||Fever |