Department of Rheumatology, Alder Hey Children's Hospital, Eaton Road, Liverpool 12, UK
SIR, Sjögren's syndrome has not been well studied in childhood but is uncommon. It may occur as a primary disorder but is more commonly secondary, occurring in association with some other autoimmune disease. Juvenile dermatomyositis is an inflammatory muscle disorder usually affecting children aged 515 yr. There are approximately 3 cases per million population per year, with a 2:1 female:male ratio. The causation is unknown but is likely to be multifactorial [1]. An association with Sjögren's syndrome has not been reported previously.
We describe here a 14-yr-old male who presented with a left pre-auricular swelling that had been present for the previous 34 weeks. There was no evidence of facial nerve weakness. He had no other significant medical history and no family history of autoimmune disease. The initial impression was of a viral sialadenitis but, following review in the maxillofacial out-patients department, a magnetic resonance imaging (MRI) scan of his parotid glands and a sialogram was arranged.
Prior to these investigations, he returned with further complaints of general malaise, weight loss and joint pains affecting his hands, feet and wrists. A photosensitive scaly rash had developed over the preceding week, affecting his hands and neck. This hadn't cleared despite treatment with topical hydrocortisone. On referral to the rheumatology service, he was found to have scaly erythematous plaques on his knuckles, elbows and knees (Fig. 1). A violaceous rash had developed around his eyes. There was no discernible muscle weakness and he denied any muscle pain. He had a left parotid swelling. The clinical impression was of a connective tissue disorder, most probably juvenile dermatomyositis. The significance of the parotid swelling was uncertain but the possibility of associated Sjögren's syndrome was considered.
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Parotid swelling is common in childhood and may be due to a variety of causes, including mumps, acute bacterial infection and salivary stones. Rarer causes include tumours, HIV, tuberculosis and dental conditions [2]. Parotitis is suggested to be the most common presenting symptom in Sjögren's syndrome in children compared with adults [3], and this was the case with our patient.
Sjögren's syndrome is a rare diagnosis in both childhood and adolescence [4]. The incidence in adults is suggested at 0.2% but the incidence in childhood is unknown. The clinical features are due to lymphocytic infiltration of the lachrymal and parotid glands. Secondary Sjögren's syndrome is found in association with other autoimmune disorders, including systemic lupus erythematosus and rheumatoid arthritis.
The criteria required for the diagnosis of Sjögren's syndrome remain controversial. In adults, the San Diego criteria include objective keratoconjunctivitis, xerostomia and either a minor salivary gland biopsy or characteristic antibodies. In contrast, the European criteria can be satisfied by a history of sicca symptoms and abnormal salivary gland scintigraphy [5, 6]. The situation in the paediatric population is even less clear. One recent study included clinical symptoms of keratoconjunctivitis sicca as well as sialography, scintigraphy and lip histology in its classification [7].
In our patient, the diagnosis of Sjögren's syndrome, which was suggested initially by the painless parotid swelling, was confirmed by the positive radiological findings on parotid imaging and the objective evidence of dry eyes. In our experience, ultrasound gives superior information compared with MRI and sialography and is the investigation of choice in children. Lip biopsy is unacceptable to most children.
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