CASE REPORT

The patient was referred to us because a biopsy of the appendix removed at surgery had disclosed necrotising vasculitis (fig 1), and her serology had shown positive antinuclear antibodies (ANA), 1/320 homogeneous. She had received bronchodilators in the past, amoxicillin clavulanate, oral contraceptives, and fenfluramine for a short time. No recent vaccination had been administered. She denied systemic symptoms, arthralgias or arthritis, skin or mucosal lesions, abdominal pain or rectal bleeding, sicca symptoms, or Raynaud’s phenomenon. After surgery she had lost 45 kg and, as expected, she had been experiencing mild abdominal cramps and diarrhoea shortly after meals. Physical examination was normal.

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Figure 1

Small artery of the appendiceal wall, showing fibrinoid necrosis of the intima, and inflammatory infiltrate, consisting predominantly of lymphocytes in and around the vessel wall (haematoxylin and eosin ×400, original magnification).

Routine laboratory investigations, including haematology, biochemistry, and urine analysis, chest x ray examination, and a purified protein derivative skin test were normal. Besides the positive ANA, complete serology, including antineutrophil cytoplasmic antibodies perinuclear and cytoplasmic, anti-proteinase 3, and anti-myeloperoxidase antibodies, and tests for hepatitis B and C virus, was unrevealing. Abdominal and cardiac ultrasound, mammography, and PAP test were normal.

A biopsy of skin and muscle of the gastrocnemia did not show abnormalities. An abdominal multislice computed tomography-angiography was consistent with vasculitis of the polyarteritis nodosa (PAN) type, showing bead-like, concentric stenoses and dilatations of multiple branches of the superior mesenteric artery (fig 2).

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Figure 2

Multislice CT angiography of the abdomen. Obstruction of the superior mesenteric artery 6 cm after its origin and for 1.5 cm is noted, followed by reinfusion, supplemented by a large jejunal arterial branch, originating above the obstruction. Narrowing of the latter is seen at about its middle. Several jejunal branches of the superior mesenteric artery disclose stenoses at multiple sites, followed by mild dilatation (bead-like configuration). A small narrowing can be seen at the first portion of the right renal artery as well.

The diagnosis of a medium and small, muscular-type, necrotising arteritis was made, albeit silent, and the patient followed up closely. Today, 15 months after surgery, she has remained clinically asymptomatic, without laboratory abnormalities, enjoying a normal life and approaching the ideal body weight.

DISCUSSION

Vasculitis of the PAN type, localised to the appendix or the gall bladder, has been accidentally found, usually after surgery.¹ Its prognosis is almost always good, in contrast with vasculitis that is found when systemic PAN has already been diagnosed.¹ Several possibilities can be suggested for the aetiology of the diffuse intra-abdominal vasculitis of our patient. Firstly, a relationship with the operation can be easily excluded because the disease was already present in the appendix before the procedure.

A second possibility may implicate the morbid obesity of the patient. Intra-abdominal processes such as pancreatitis and malignancy, but other systemic diseases also, such as infectious endocarditis, atrial myxoma, and drug abuse, have been reported to mimic the visceral angiographic appearance of vasculitis.² No such problems were present, and furthermore, morbid obesity has never been reported to cause vasculitis.

The positive ANA may suggest systemic lupus erythematosus as a third possibility, but our patient had no other evidence to support this diagnosis.

Drug induced vasculitis may be a fourth possibility.^3–6 In the vast majority of cases it affects the skin, but it may extend to internal organs. The diagnosis is usually one of exclusion and a timely relationship to the offending drug should be documented. Almost any drug can be blamed. However, it is rather unlikely that one of the drugs the patient had taken would have induced abdominal vasculitis, without skin manifestations.

Finally, it is quite likely that our patient had asymptomatic PAN, which will either remain as such, or will become manifest in the future. In such cases, clinicians should be aware of the possibility that a systemic necrotising vasculitis may, for some time, remain asymptomatic. Furthermore, mesenteric angiography, when used to help diagnose PAN in cases of multisystem clinical presentations, is not expected to disclose vasculitis when hepatic enzymes are normal,² but even then the procedure may be of diagnostic help.