Divisions of Rheumatology, 1Pathology,
2 Vascular Surgery and
3 Traumatology, Hospital Xeral-Calde, Lugo, Spain
SIR, Classical polyarteritis nodosa (PAN) is a systemic illness in which the pathological lesion defining this vasculitis is a focal segmental necrotizing inflammation of medium-sized and small arteries, less commonly arterioles, and only rarely venules [1]. In some cases, the pathological lesion appears to be limited to one organ without detectable systemic disease [26]. We describe a patient with necrotizing arteritis of small and medium-sized arteries located in the calf muscles and mimicking deep venous thrombosis (VT).
A 71-yr-old man was sent to the rheumatology out-patient clinic because of a painful indurate area on the right calf with distal oedema. Two months earlier he had been studied at the vascular surgery department of the hospital because of pain associated with a hard knot along the venous course in his calf. A suspicion of superficial venous thrombosis was made. Bed rest with elevation of the extremity and non-steroidal anti-inflammatory drugs were prescribed. However, no improvement of the process was observed. As superficial VT occurs frequently in association with deep VT [7], a Doppler sonographic examination and a careful phlebographic study were performed. Doppler scanning disclosed a low-attenuation signal lesion. Phlebography showed total obstruction of the popliteal vein (Fig. 1). A diagnosis of external compression at the popliteal vein was made. Also, at that time a computed tomography scan disclosed a low-density mass. On admission to the Rheumatology Division, there was a firm, tender, non-pulsatile swelling in his right calf and pitting oedema in the right foot and calf was detected. Magnetic resonance imaging showed diffuse muscle enlargement. Open biopsy showed necrotizing arteritis of small and medium-sized arteries with fibrinoid necrosis and neutrophils as well as lymphomononuclear cells in the artery wall. Laboratory findings showed an erythrocyte sedimentation rate of 40 mm/1st h and a C-reactive protein concentration of 12 mg/l (normally <5 mg/l). Other laboratory parameters, including creatinine, glucose, hepatic function tests, rheumatoid factor, antinuclear antibodies, anti-DNA, complement C3 and C4, anticardiolipin antibodies, cryoglobulins, anti-neutrophil cytoplasmic antibody and the urine biochemistry profile, were negative or normal. The chest radiograph and abdominal ultrasonography were also normal. A diagnosis of localized vasculitis, which fulfilled pathological definitions of PAN, was made and the patient was started on prednisone 1 mg/kg/day orally and methotrexate 15 mg/week in a single oral dose. Progressive improvement was observed and the venous obstruction gradually resolved.
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Notes
Correspondence to: M. A. Gonzalez-Gay, Division of Rheumatology, Hospital Xeral-Calde, c/Dr Ochoa s/n, 27004 Lugo, Spain.
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