Statistics from Altmetric.com
Juvenile idiopathic arthritis (JIA) is a heterogeneous group of arthritis occurring in children under the age of 16. It is a complex multifactorial disease with genetic, immunological, and environmental factors strongly associated with causation.1 2 The incidence of JIA in the UK varies from 10 to 20/100 000/year, with a prevalence of 1/1000.3
Idiopathic atrophoderma, as described by Pasini and Pierini, is a distinctive form of dermal atrophy seen particularly in children and younger people.4 There are usually no clinical signs of inflammation or symptoms. We report on a 13 year old girl with JIA and atrophoderma. Although considered a variant of morphea, atrophoderma is thought to be a distinct nosological entity. We believe that this is the first time an association between the two has been described.
A 13 year old girl was referred by her general practitioner with a four month history of joint swelling and stiffness. The symptoms were mainly of the small joints of the hands and wrists. She also had early morning stiffness of the same joints and of the neck. On initial examination she was noted to have a diffuse purple, slightly atrophic patch on her lower back, which was symmetrical and pear shaped. The patch measured 22×15 cm and showed subtle features of dermal atrophy with more visible vascular marking than in the surrounding skin (fig 1). Her musculoskeletal examination showed swelling with synovial thickening of all the proximal interphalangeal and distal interphalangeal joints with some metacarpophalangeal joints affected also. The rest of the systemic examination was normal. Her baseline haematology, including an erythrocyte sedimentation rate of 8 mm/1st h (normal <10), and biochemistry, including C reactive protein <6 mg/l (normal <6), were within normal limits. Antinuclear antibody was positive at 1 in 100 dilution and extractable nuclear antigen was negative. She was also rheumatoid factor positive at a dilution of 1 in 256. The rest of her immunology, including complement assays, was normal.
A diagnosis of JIA was made and treatment was started with ibuprofen 30 mg/kg/day. Although she showed some response, the joint swelling and early morning stiffness persisted and hence treatment was started with methotrexate at 12.5 mg/week subcutaneously as she did not favour the oral route. She has responded well to the methotrexate and her joint symptoms are under good control. Six months after the onset of the arthritis she developed a new patch of atrophoderma on the left deltoid area measuring about 9×10 cm.
Atrophoderma of Pasini and Pierini (APP) can occur at any age, but usually develops in the teens or the 20s. Childhood presentation is not uncommon, and various reviews have shown that this subtype comprises between 10 and 15% of all childhood morphea.5 6 The cause remains uncertain although infective agents, particularly Borrelia burgdorferi, have been implicated in few reports.7APP has a female to male ratio of 2:1. The distinction of this condition from morphea was thought to be important to avoid the use of aggressive immunosuppressive treatment. There are no reports so far of an association between APP and JIA or the presence of antinuclear antibody and rheumatoid factor.
We feel our case illustrates a few important features about APP, especially that prolonged follow up is essential when a diagnosis is made in children as there is a possibility of them developing other rheumatological conditions. It is interesting to note that despite the fact that our patient was receiving methotrexate, the lesions did not regress and she developed a new lesion after starting methotrexate. Joint symptoms in a child with APP need to be evaluated and there may be an increased risk for developing JIA. It is also interesting to note that our patient developed a patch in her upper arm, which might be a “self involuting atrophoderma of the lateral upper arm”, a distinct entity which has been described recently.8 Although the cause of both is not clearly understood, immunological mechanisms to as yet unidentified antigens appear to underlie the pathogenesis. We speculate that the underlying trigger may be a common infective pathogen which activates the immune system.