medwireNews: Routine use of magnetic resonance imaging (MRI) for girls with central precocious puberty (CPP) is the best way to identify occult central nervous system (CNS) lesions, say Turkish researchers.

In their analysis of 770 CPP patients who underwent cranial MRI between 2005 and 2017, imaging detected new lesions causally linked to CPP in an estimated one in every 14 girls aged less than 6 years and one in every 31 cases among older girls.

Girls who developed breasts before age 6 years or had a peak luteinising hormone to follicle stimulating hormone (LH/FSH) ratio above 0.6 were a significant 2.38 and 3.13 times more likely to have CNS lesions, respectively, than other CPP patients.

But age was only 28% sensitive and 87% specific for predicting the likelihood of clinically significant CNS abnormalities in girls with CPP, with corresponding values for peak LH/FSH ratio of 78% and 47%, prompting the study authors to say that “none of the predictors were robust enough to be used for decision-making regarding the necessity of MRI investigation.”

Overall, 13.5% of girls in the multicohort study had abnormal cranial MRI findings, of which 10.6% were new findings; 3.8% of these were causally linked to the CPP diagnosis, 3.1% were possibly related to CPP and 3.8% were incidental, report Abdullah Bereket (Marmara University, Istanbul) and co-authors in The Journal of Clinical Endocrinology & Metabolism.

Just 0.6% of the study participants required intervention for their MRI-detected abnormalities – four patients diagnosed with hamartoma underwent surgery for refractory epilepsy and a fifth patient underwent surgery for an enlarging Rathke cleft cyst compressing the pituitary gland.

If cranial MRI had been used only in CPP patients aged less than 6 years, the enlarging Rathke cleft cyst would not have been detected, the researchers say.

In addition, both neoplasms detected by cranial MRI were in girls aged over 6 years, albeit neither the meningioma nor the low-grade glial tumour required intervention during follow-up over 3.5 and 6.0 years, respectively.

“Hence, in the absence of reliable clinical or biochemical predictors, systematic cranial MRI seems to be the most efficient current approach to avoid missing the diagnosis of pathological CNS lesions in girls with CPP, independently of age of puberty onset and despite the low likelihood of finding a lesion requiring intervention”, Bereket et al write.

“The question remains about whether systematic imaging is cost-effective and should be done in girls >6 years given the above data”, conclude the researchers.

They suggest: “An alternative approach would be to notify the parents of the low likelihood of finding an intracranial tumor in those >6 years and discuss pros and cons of MRI scanning to assist them in making an informed decision.”

By Lynda Williams

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J Clin Endocrinol Metab 2021; doi:1 0.1210/clinem/dgab190

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