A case report of Farber disease with extensive Mongolian spots

Background Extensive Mongolian spots are a common skin finding in healthy infants, and several lysosomal storage diseases have been reported to be associated with extensive Mongolian spots. To date, no association between Farber disease and extensive Mongolian spots has been reported. Case presentation The patient was a 4-year-old Chinese girl who showed Mongolian spots that had spread across her trunk and limbs beyond the waist since birth. At 18 months of age, she visited our hospital because of the absence of meaningful speech and inability to walk. She presented with a short stature and swelling of finger joints accompanied by subcutaneous nodules. Whole-genome sequencing identified compound heterozygous variants in ASAH1 . A biopsy of a subcutaneous nodule showed granuloma formation and foamy cells, leading to a definitive diagnosis of Farber disease. At 4 years of age, the extensive Mongolian spots persisted without regression. Discussion To the best of our knowledge, this is the first report of extensive Mongolian spots in a patient with Farber disease. Extensive Mongolian spots in this patient may not be incidental, and they may be one of the symptoms of Farber disease.