It has been previously suggested that children with JIA are at an increased risk of malignancies when being treated with anti-TNF therapy. More recent data has not confirmed this association: it is thought that the disease itself is linked with a slightly higher background risk of malignancy. Ongoing data analysis on large patient populations continues in this area. Epidemiology
Juvenile Idiopathic Arthritis is the most common, chronic rheumatic disease of childhood. In high-income countries, yearly incidence has been estimated at 2–20 cases per 100,000 population; prevalence in these areas is estimated at 16–150 cases per 100,000 population. However, there is also a suggestion that these numbers underestimate disease prevalence: one community-based survey of school children in Western Australia reported a prevalence of 400 per 100,000. Overall prevalence is often summarised as one per thousand children.Incidence and prevalence data vary across different population and ethnic groups, with lower overall prevalence in Afro-Caribbean and Asian populations. There are also ethnic differences in the frequency of JIA subtypes: for example, oligoarthritis is the most common subtype in European populations, whilst polyarticular disease predominates in many other countries including Costa Rica, India, New Zealand, and South Africa.There are differences in age of onset, gender and disease outcomes based on JIA subtype: these are outlined in the table above. Terminology
The terminology used to describe JIA is evolving, and each term has some limitations. Previous terminology included Juvenile Rheumatoid Arthritis and Juvenile Chronic Arthritis.
They are also seen in patients with end-stage kidney disease on hemodialysis, Hodgkins disease, pellagra, and sickle cell anaemia.The lines remain visible as long as protein intake is inadequate or synthesis is impaired, and they should disappear upon return to normal function.In extreme conditions, Muehrckes lines may also arise from physical changes in peripheral circulation: one case study reported appearance of the lines in a healthy subject following ascent to 8,848 meters (29,029 ft) on Mount Everest. History
Muehrckes lines were described by American physician Robert C. Muehrcke (1921–2003) in 1956. In a study published in BMJ, he examined patients with known chronic hypoalbuminemia and healthy volunteers, finding that the appearance of multiple transverse white lines was a highly specific marker for low serum albumin (no subject with the sign had SA over 2.2 g/dL), was associated with severity of the underlying condition, and disappeared upon successful treatment (corticosteroids in nephrotic syndrome) or direct infusion of HSA. See also
Mees lines – a similar appearance, except the lines are in the nail and move as the nail grows
Half and half nails
Terrys nails
List of cutaneous conditions

References
Bibliography
Fawcett, Robert S.; Sean Linford; Daniel L. Stulberg (March 15, 2004). "Nail Abnormalities: Clues to Systemic Disease". American Family Physician. 69 (6): 1417–24. PMID 15053406. James, William; Berger, Timothy; Elston, Dirk (2005). Andrews Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0-7216-2921-0. Muehrcke Lines of the Fingernails at eMedicine
Muehrckes Lines of the Fingernails on WebMD