On the Case
By Joseph Ryan, MD, and Alex Merkulov, MD  
Radiology Today
Vol. 24 No. 8 P. 34

A 60-year-old man with a personal history of right-sided renal cell carcinoma, status post partial nephrectomy approximately six months prior, presented to the emergency department (ED) with a two-week history of a rash (diffuse palpable purpura) that started on his lower extremities and subsequently moved up to his torso and arms. The patient also reported a two-day history of new-onset abdominal pain, which was progressively worsening. He had no nausea, vomiting, or fever. He was recently evaluated by dermatology, underwent a skin biopsy, and was told that he had immunoglobulin A (IgA) vasculitis. He was completing his prescribed prednisone taper when his abdominal symptoms began. He reported that his skin findings were improving. A contrast-enhanced CT of the abdomen and pelvis was obtained to investigate the etiology of the patient’s new-onset abdominal pain.

CT revealed characteristic signs of small bowel inflammation, most prominently within the midabdomen. Representative axial (Figure 1), coronal, and sagittal (Figures 2 and 3) CT images are shown. Specifically, there was evidence of small bowel wall thickening and hyperemia (Figures 1 to 3), as well as inflammatory changes of the bowel mesentery and vascular engorgement (Figures 1 and 3). Also seen was smallvolume right paracolic gutter free fluid (Figure 1) and an incidentally noted small right kidney lower pole low-attenuation masslike focus superimposed on postsurgical change, status post right renal mass resection approximately six months prior.

Left lower extremity skin biopsy results demonstrated a predominance of perivascular IgA over C3 deposition within the spectrum of an IgA-mediated small-vessel vasculitis (including Henoch-Schonlein purpura). Periodic acid-Schiff and Gram stains were negative for fungal elements or bacteria. Direct immunofluorescence studies revealed superficial perivascular IgA (2-3+, granular) and C3 (trace-1+, granular) with interstitial fibrinogen (3+) deposition; they were negative for definitive IgG or IgM deposition.

Prior autoimmune workup demonstrated normal C3, C4, negative antinuclear antibody, negative extractable nuclear antigen, negative double stranded- DNA, negative rheumatoid factor, negative cryo, negative myeloperoxidase/ proteinase-3/antineutrophil cytoplasmic antibodies, negative antiphospholipid antibodies, normal IgG4, normal IgA level, normal serum protein electrophoresis. Hepatitis B surface antigen, hepatitis B core antibody IgM, and hepatitis C antibody were also negative.

Upon admission, the patient was treated with a three-day pulse of IV solumedrol for IgA vasculitis with improvement in abdominal pain. In addition to clinical improvement, his inflammatory markers also gradually responded favorably. He was discharged on 40 mg of daily prednisone.

Enteritis due to IgA vasculitis

Although, in this case, the diagnosis of IgA vasculitis as the underlying etiology preceded his imaging workup, this is unfortunately not always the case. Accordingly, the differential diagnosis for a patient presenting with the above symptoms and imaging findings is worthy of further discussion, given how common this nonspecific presentation can be encountered.

Relatively young age and only mild atherosclerosis of the patient’s major arteries suggested that ischemic enteritis was not a serious consideration as an etiology. A diffuse infectious process was also deemed unlikely due to the relatively short segment of small bowel involved. Infectious enteritis can present with focal bowel involvement and was, therefore, a differential consideration here. However, the patient’s leukocytosis on presentation was likely secondary to the high-dose steroids with which he was being treated for his vasculitis.

IgA vasculitis is one of many different types of vasculitides that can be encountered in clinical practice. Formerly known as Henoch-Schönlein purpura, IgA vasculitis is a small-vessel vasculitis characterized by the deposition of IgA-immune complexes within vessel walls.1,2 Despite identification of different triggers, such as viruses, drugs, and vaccines, that can lead to development of IgA vasculitis, no precise underlying cause has ever been demonstrated.3 

IgA vasculitis most frequently involves children, and it is, in fact, the most common type of vasculitis affecting children, with peak incidence at around 5 years of age.4

IgA vasculitis affects multiple organs and organ systems, with typical involvement of the skin, joints, gastrointestinal tract, and kidneys.5,6 The typical clinical presentation reflects this constellation of multiorgan involvement, with the characteristic purpura rash occurring in virtually all pediatric cases and is the initial presenting symptom in nearly three out of four pediatric cases.7,8

Additional symptoms that are common include fever, arthralgia, hematuria, abdominal pain, and related gastrointestinal symptoms such as diarrhea. The diagnosis of IgA vasculitis can typically be made on the clinical constellation of signs and symptoms, as well as histopathological evidence of leukocytoclastic vasculitis associated with IgA deposition within small vessel walls.1,9 Laboratory findings supportive of, though not specific for, a diagnosis of IgA vasculitis include leukocytosis, elevated inflammatory markers such as C-reactive protein, serum transaminases, lactate dehydrogenase, and creatine kinase.1,10 Elevated levels of interleukin-2 and decreased activity of serum factor XIII may also be indicative of IgA vasculitis.10 Gold standard for diagnosis is skin biopsy, as was performed in this patient’s case prior to presentation to the ED. Early skin biopsy should be done as soon as IgA vasculitis is suspected due to diagnostic yield being highest when performed within 48 hours after onset.

Treatment typically involves steroids, which are usually effective in providing symptomatic relief. Often, patients are also treated with antibiotics for presumed infectious gastroenteritis at initial presentation, concurrently or prior to definitive diagnosis of vasculitis and initiation of glucocorticoid therapy.

In fact, gastrointestinal symptoms can precede cutaneous manifestations in 15% to 35% of IgA vasculitis adult patients. Compared with pediatric patients affected by IgA vasculitis, adult patients are more likely to experience more severe renal involvement, as well as higher incidence of GI symptoms, though typically lesser incidence of arthralgia. Even in cases where adult patients initially develop purpura, the rash must be accurately recognized, documented appropriately, and linked to the corresponding systemic symptoms. Indeed, prompt recognition and skin biopsy as early as possible, ideally within 48 hours of rash onset, is recommended to optimize diagnostic accuracy.

Accurate and prompt diagnosis of IgA vasculitis in adults is important to avoid some of the more serious complications of untreated vasculitis when severe, most notably those related to gastrointestinal symptoms, including small bowel enteritis. These complications can include intestinal obstruction, intussusception, ischemia, perforation, and gastrointestinal hemorrhage. When these complications occur, emergency laparotomy is often required, and there are significantly increased rates of morbidity and mortality.

Imaging findings tend to be nonspecific, and accurate diagnosis of IgA vasculitis based on imaging is often predicated on prior laboratory data suggestive of IgA vasculitis and preexisting clinical suspicion for this condition. As discussed previously, this was the situation in the case presented here. Regardless, a differential diagnosis based on abdominal CT imaging findings, including small bowel wall thickening, hyperemia, and mesenteric inflammation indicative of small bowel enteritis of uncertain etiology, should include the possibility of IgA vasculitis enteritis in the proper clinical setting.11

While isolated imaging findings characteristic of enteritis are statistically most likely to represent infectious or nonspecific/ nonvascular inflammatory causes, vasculitis, as well as ischemic etiologies, should be considered depending on the underlying clinical context. Lack of significant improvement following treatment with antibiotics for a presumed diagnosis of infectious enteritis should also elicit one to consider alternative etiologies, including IgA vasculitis.

Despite the risk of major complications that can occur in severe IgA vasculitis, treatment of IgA vasculitis-related gastrointestinal conditions such as enteritis generally involves conservative management, with most patients experiencing a self-limited course and gradual improvement in symptoms. Although treatment with steroids can provide symptomatic relief, glucocorticoid therapy does not appear to impact long-term outcomes. Regardless, it is important for practicing radiologists and clinicians to recognize this relatively uncommon disease entity when it occurs. 

— Joseph Ryan, MD, is a radiology resident at UConn Health at the University of Connecticut in Farmington.

— Alex Merkulov, MD, is an associate professor of radiology at UConn Health at the University of Connecticut.