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An 81 year old man presented in October 2002 with a three week history of fatigue, generalised myalgia, increasing difficulty in getting up from the sitting position, and “pins and needles” sensation in both hands and feet. His past medical history included late onset asthma at the age of 66, which had gradually become worse over the past year, nasal polyps, and carcinoma of the bladder in 1991, which was removed by cystoscopy. His only medication was inhaled salbutomol as required.
He was unable to stand or walk without support at the time of admission and had generalised muscle wasting. He had grade 3 (Medical Research Council grading) proximal muscle weakness in both lower limbs and grade 4 proximal weakness in both upper limbs. His left handgrip was also weak. His blood pressure was 160/80 mmHg and urine showed a trace of protein and blood, but there were no casts. The rest of the examination was unremarkable.
Investigations revealed haemoglobin of 111 g/litre that was normocytic and normochromic, white blood cell count of 27.8 × 109/litre with eosinophilia of 15.4 × 109/litre, platelet count of 611 × 109/litre, erythrocyte sedimentation rate of 68 mm at one hour by the Westergreen method, C reactive protein of 91 mg/litre, urea of 8.8 mmol/litre, creatinine of 198 μmol/litre, alanine aminotransferase of 52 units/litre, alkaline phosphatase of 135 units/litre, and creatinine kinase (CK) of 272 units/litre. His eosinophil count gradually rose to 24.8 × 109/litre and his CK to 538 units/litre over the next few days. Chest radiograph was within normal limits. Renal ultrasound showed evidence of long standing right sided hydronephrosis. Creatinine clearance was reduced at 27 ml/min. Serum antineutrophil cytoplasmic antibodies (ANCA) against myeloperoxidase were positive at 42.1 au/ml, whereas serum ANCA against proteinase 3 were within normal limits. Electromyography (EMG) was normal and nerve conduction studies showed that the left median motor and sensory amplitude was smaller than on the right.
Renal biopsy was not performed because he had a solitary functioning kidney and there were no active sediments in his urine. We proceeded to open muscle biopsy, despite the normal EMG, in view of his muscle weakness, raised CK, and the need to establish a tissue diagnosis. Frozen sections stained with haematoxylin and eosin showed numerous atrophic fibres scattered throughout the biopsied fascicles, but with no convincing perifascicular distribution. However, the most striking pathological change was that of a florid inflammatory infiltrate in relation to an epimysial medium sized artery (fig 1). The infiltrate was composed of polymorphs predominantly, with smaller numbers of macrophages and lymphocytes. Occasional polymorphs had the granular eosinophilic cytoplasm suggestive of eosinophils. The infiltrate extended through the full thickness of the vessel wall and there was necrosis of the vessel wall with a fibrinoid exudate (fig 2). There was no diffuse eosinophilic infiltration of the tissues and granulomas were not seen. Paraffin wax embedded sections and electron microscopic examination provided no further diagnostic information. The appearances were consistent with an active vasculitis. When considered in conjunction with the clinical picture and investigations, the appearances suggested a diagnosis of Churg-Strauss vasculitis.
The frequency of muscle involvement in systemic vasculitis is poorly defined. Studies looking at the rate of positive muscle biopsies in systemic vasculitis showed that only 13% of biopsies were positive in patients in whom there was a clinical suspicion, whereas 35–37% were positive in patients with confirmed systemic vasculitis.1,2 As far as we are aware, there are no published reports of biopsy confirmed Churg-Strauss syndrome associated medium sized vessel vasculitis involving skeletal muscle. Classically, Churg-Strauss syndrome is associated with a medium sized vessel vasculitis, diffuse eosinophilic tissue infiltrates, and necrotising granulomas. However, it is rare to find all three histological features in a single biopsy because the lesions tend not to coexist either anatomically or temporally.3
Remission was induced in our patient with a combination of prednisolone, mycophenolate mofetil, and intravenous immunoglobulin.