THE JOURNAL OF PEDIATRICS VOLUME 136, NUMBER I

LETTERS

Sherry.1 Health care providers should be aware of this increased risk of evo- lution to polyarticular arthritis in the group of children with small joint dis- ease at onset.

Sanjiv H. Naidu, AID, PhD Assistant Professor

Department of Orthopedics and Rehabilitation

Barbara E. Ostrov, AJD Associate Professor

Pediatric and Adult Rbeamatology Departments of Pediatrics and Medicine

Vincent D. Pel@rin£ AID Professor and Chair

Department of Orthopedics and Rehabilitation

PennState Geisinger Health System Hershey, PA 17057

9/35/103006

REFERENCES

l. Sharma S, Sherry DD. Joint distri- bution at presentation in children with pauciarticular arthritis. J Pediatr 1999;134:642-3.

2. Naidu SH, Ostrov BE, Pellegrini VD. Isolated digital swelling as the initial presentation of juvenile rheumatoid arthritis. J Hand Surg 1997;22A:653-7.

Reply To the Editor:

Naidu et al raise an important point, because both family and physician want to know what will happen to the children presenting with pauciarticu- lar arthritis over the ensuing years. We are presently an@zing the 3-year fol- low-up data on our 215 patients. A major problem arises with the defini- tion of progression to polyartieular dis- ease because there exists, to our knowledge, no empiric evidence that 5 joints with arthritis are biologically dif- ferent from 4 such joints or that the final outcome is any different. The def- inition of polyarticular disease, in our minds, might be better defined as over 10 joints with arthritis, although this is an arbitrary bias of ours.

Only one of the 215 children with paueiarticular arthritis in our study progressed to have widespread arthri- tis, that is, 31 joints involved with

arthritis. This child only had bilateral knee arthritis at 6 months into her ill- ness. Another child later developed arthritis in 14 joints. Additionally, 24 children developed arthritis in up to 9 joints over the ensuing 3 years. Of these 26 children, 14 had small hand joint involvement (P < .0001, Fischer exact test, 2-sided). The increased fre- quency of the development of arthritis in more than 5 joints in children with small hand joint disease may be related to the fact that there are many more small joints of the hands than there are larger joints. There may also be an in- trinsic difference between those with and without small joint hand arthritis, although in our study the prevalence of uveitis was not different between those with small versus large joint arthritis.

Therefore, the biologic and prognostic significance of initial small joint arthritis is probably minimal but warrants fur- ther study. We agree that the delay in di- agnosis is a problem, but it can be reme- died by physician awareness.

Seems Sharma, A~RCP (UK) David D. Sherw, AID Rbeumatology CH- 73

Children's Hospital & Regiona/ ~/ledica/ Center

4800 Sand Point Way, NE Seattle, WA 98105

9/35/103005

Diagnostic dilemma caused by overlapping features of Prader-Willi syndrome and trisomy 18 during infancy To the Editor:

The report by Miller et all effective- ly illustrates the difficulty in early di- agnosis of Prader-Willi syndrome (PWS). They describe 6 newborns with hypotonia who were not diag- nosed with PWS until an average age of 17 months. We would like to draw attention to 3 additional infants with dysmorphie hypotonia, demonstrating similarities between PWS and other congenital disorders (eg, trisomy 18).

Our first subject was a 20-month-old girl referred because of developmental delay and growth retardation. Prenatal histo W was significant for a ehoroid plexus cyst, identified by routine

F~ure. Frontal view of 20-month-old female subject with trisomy 18 mosaicism.

sonography, and decreased fetal move- ment. She was born at term, weighing 2.8 kg (10th centile), and was 49.5 cm (30th centile) long. She had hypotonia, respiratory distress, and significant feeding difficulties requiring tube feed- ings. Ear tubes were placed in early in- fancy because of chronic infections. Strabismus was present by 1 year of age. She sat at 1 year, crawled at 15 months, and spoke a few words at 20 months, at which time her height was 78.8 cm (10th centile), weight 9.27 kg (5th eentile), head circumference 46.1 cm (25th centile), and hand length 9 cm (3rd centile). She also had a nar- row bifrontal diameter, dolichocephaly with mild ridging of the sagittal and metopic sutures, almond-shaped eyes, a small mouth with down-turned cor- ners and a thin upper lip, a short nose, narrow appearing hands, a systolic murmur (small ventricular septal de- fect), and hypotonia (Figure). PWS was considered because of these find- ings and chromosome testing per- formed with fluorescent in situ hy- bridization analysis. Trisomy 18 mosaicism (47,XX,+18 [23 cells]/46,XX [27 cells]) was found with no evidence of a 15@1-@3 deletion. Results of DNA methylation analysis were nor- real. Trisomy 18 is a classical malfor- mation syndrome with features com- mon to PWS including decreased fetal activity, weak cry and suck, narrow bifrontal diameter, small mouth, cwp-

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