5 | DISCUSSION
An acquired immune-mediated disorder, NLE is an extraordinary occurrence, caused by maternal IgG antibodies against Ro/SSA, La/SSB, or U-RNP in the newborn. It occurs in approximately 1 per 20,000 newborns,1and 2% in offspring of mothers with Sjögren’s syndrome with an 18 to 20 percent recurrence rate in subsequent pregnancies.3
Clinical signs of NLE may include annular skin rash, cytopenia, hepatitis, and congenital heart block. It is essential to keep track of these patients over time, as they are more prone to autoimmune disorders in later childhood or adulthood.4
Confirmation of the diagnosis of NLE can be achieved by considering the patient’s medical history, conducting a physical examination, and detecting the presence of specific antibodies in both the fetus and the mother. While a skin biopsy is helpful, it is not necessary in order to establish the diagnosis. Other conditions that may need to be considered when making a differential diagnosis include congenital syphilis, tinea corporis, sarcoidosis, granuloma annulare, Langerhans histiocytosis, Sweet syndrome, and urticaria.
While cases of NLE among siblings have been reported,5they typically present with the same or similar manifestations, making it a rare occurrence due to the increased risk of pregnancy in affected women. In our cases, it is very interesting that cutaneous NLE occurs in two siblings with significantly different cutaneous manifestations. The various clinical expressions may be attributed to a different specificity of Anti-Ro autoantibodies among siblings.6 Additionally, other foeto-maternal factors including environmental, intrauterine, or genetic influences may affect the pathogenesis and expression of NLE.7
It is believed that pregnant women who test positive for autoantibodies to Sjögren’s syndrome autoantigens types A or B are considered to have a high-risk pregnancy, particularly those with a prior history of NLE,8 due to the increased danger of NLE in offspring of future pregnancies.3
It was deemed highly hazardous for the mother and her unborn child not to keep track of the fetal PR interval through echocardiogram during gestation, thus necessitating the implementation of counseling advice, fetal screening, maternal screening, and prevention or management of heart disease.8 Current recommendations are to conduct an echocardiogram weekly between 16-26 weeks’ gestation and biweekly between 26-32 weeks.
The mainstay of management for infants with cutaneous manifestations is to actively prevent sun exposure by utilizing methods such as sunscreen and protective clothing,9 just like in our cases, both children only presented with rashes, the key of the management is photoprotection.
The sister followed up for 7 years and the younger brother followed up for 1 year. So far, neither of the siblings has experienced any recurrence of skin lesions, and developed any autoimmune diseases. At present, both siblings are still following up at the outpatient clinic to monitor biochemical tests、echocardiogram and ECG.
As global fertility declines, many countries are implementing policies to stimulate fertility growth. The Chinese government, for instance, liberalized the two-child policy in 2016,10 and further liberalized the ”three-child” policy in 2021. This has not caused a baby boom, but rather a moderate rise in fertility,11 resulting in more families having a second child.2Therefore, it is estimated that the incidence rate of NLE in siblings will increase too, so we should raise the awareness of NLE in siblings, which is very important for the monitoring, evaluation, diagnosis and management of NLE.