Departments of Nephrology and 1Pathology, Great Ormond Street Hospital for Children, London, UK
Correspondence to: D. Hothi. E-mail: dhothi{at}ich.ucl.ac.uk
SIR, A 13-yr-old Caucasian boy presented with an 8-month history of night sweats, intermittent fever, occasional cough, lethargy, myalgia and headaches. The initial examination was unremarkable, and investigations showed haemoglobin of 8.1 g/dl, white blood cell count of 13.9 x 109/l, platelet count of 899 x109/l, erythrocyte sedimentation rate (ESR) of 133 mm/h, C-reactive protein (CRP) of 3 mg/dl and creatine kinase of less than 20 units/l (reference range 0120 U/l). Over the next 3 months he developed abdominal pain, aphthous mouth ulcers and diarrhoea with a total weight loss of 4 kg.
Further investigations demonstrated a persistent anaemia, ESR of 150 mm/h, CRP of 14 mg/dl and mildly elevated transaminases. The autoantibody profile, serology for viral hepatitis, EpsteinBarr virus, cytomegalovirus, Borrelia burgdorferi and Brucella, and Mantoux test were all negative. A diagnosis of polyarteritis nodosa was made following a renal and coeliac axis angiography demonstrating small hepatic arterial aneurysms (Fig. 1A), and pruning of the peripheral arteries of the right kidney. Subsequent treatment comprised pulsed intravenous methyl prednisolone (600 mg/m2), followed by oral prednisolone (2 mg/kg daily) and oral cyclophosphamide (2 mg/kg daily).
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Subsequent excision of the mass revealed a friable tumour with an irregular surface and a cystic, haemorrhagic and papillary appearance. Microscopy (Fig. 1B) showed irregular nodules of pale, oval cells with minimal pleomorphism and few mitotic figures. The capsule was incomplete comprising dense fibrous tissue with a prominent mixed chronic inflammatory cell infiltrate. Scattered chronic inflammatory cells and blood-filled spaces were visible within the tumour. Desmin antibody staining was positive. The picture was that of an angiomatoid fibrous histiocytoma (AFH). Following surgery his symptoms and acute-phase reactants dramatically improved.
Four months later he developed a fever, myalgia and general malaise in association with anaemia and elevated ESR and CRP. Examination revealed a smooth cystic lesion palpable deep to the site of his previous surgery. Because of the close proximity of the mass to the sciatic nerve, medical management with daily prednisolone (60 mg/m2) was attempted, but his symptoms and acute-phase reactants failed to respond. Consequently the recurrent mass was excised and histology confirmed recurrent AFH. Within 2 weeks his symptoms resolved, with normalization of the acute-phase response. Six months following the tumour resection, his immunosuppressive therapy was stopped, with no recrudescence of the systemic symptoms at 18 months.
AFH is a soft tissue tumour of children and young adults characterized by sheets of bland rounded cells or spindle cells separated by areas of cystic haemorrhage and often surrounded by a fibrous pseudocapsule [12]. It can be associated with an abundant inflammatory component and systemic manifestations that seem out of proportion to the size and extent of the tumour [3]. In our patient the mass was not obvious at initial presentation, but it is almost certain that the findings, although compatible with the diagnostic criteria for polyarteritis nodosa [4], were secondary to the AFH. Systemic symptoms were reported in 10% of patients in a small series of AFH [5]. To the best of our knowledge this is the first case report of an AFH mimicking a systemic vasculitis.
AFH is classically associated with a striking lymphoplasmacytic inflammatory reaction. Perhaps through the production of pro-inflammatory cytokines such as tumour necrosis factor-, AFH-mediated endothelial activation, leucocyte adhesion and structural vascular damage culminate in the clinical picture of vasculitis and the documented arteriographic findings. Although this hypothesis remains speculative, AFH can simulate Castleman's disease [6], a disorder occasionally causing a reactive systemic vasculitis in children [7]. Whatever the mechanism, the improvement of symptoms and normalization of inflammatory markers immediately after surgical removal of the primary and recurrent AFH strongly suggest that the vasculitis and systemic upset was secondary to the tumour.
AFH is said to be a low-grade malignant tumour [8] but with a recurrence rate of 1223.2% and a metastasis rate of 4.68.7% [89]. We continue to monitor our patient by clinical symptoms and inflammatory markers, with 6-monthly MRI of the primary tumour site.
This case illustrates that AFH can masquerade as a spectrum of diseases with profound systemic upset before any mass lesion is clinically detectable. We would emphasize that tumours need to be considered in the differential diagnosis of children with vasculitis, especially with failure to respond to conventional treatment [10].
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