LEOPARD syndrome: clinical dilemmas in differential diagnosis of RASopathies.
BACKGROUND
Diagnosis within RASopathies still represents a challenge. Nevertheless, many efforts have been made by clinicians to identify specific clinical features which might help in differentiating one disorder from another. Here, we describe a child initially diagnosed with Neurofibromatosis-Noonan syndrome. The follow-up of the proband, the clinical evaluation of his father together with a gene-by-gene testing approach led us to the proper diagnosis.


METHODS
We report a 8-year-old male with multiple café-au-lait macules, several lentigines and dysmorphic features that suggest Noonan syndrome initially diagnosed with Neurofibromatosis-Noonan syndrome. However, after a few years of clinical and ophthalmological follow-up, the absence of typical features of Neurofibromatosis type 1 and the lack of NF1 mutation led us to reconsider the original diagnosis. A new examination of the patient and his similarly affected father, who was initially referred as healthy, led us to suspect LEOPARD syndrome, The diagnosis was then confirmed by the occurrence in both patients of a heterozygous mutation c.1403 C > T, p.(Thr468Met), of PTPN11. Subsequently, the proband was also found to have type-1 Arnold-Chiari malformation in association with syringomyelia.


CONCLUSIONS
Our experience suggests that differential clinical diagnosis among RASopathies remains ambiguous and raises doubts on the current diagnostic clinical criteria. In some cases, genetic tests represent the only conclusive proof for a correct diagnosis and, consequently, for establishing individual prognosis and providing adequate follow-up. Thus, molecular testing represents an essential tool in differential diagnosis of RASophaties. This view is further strengthened by the increasing accessibility of new sequencing techniques.Finally, to our knowledge, the described case represents the third report of the occurrence of Arnold Chiari malformation and the second description of syringomyelia with LEOPARD syndrome.
Claudia
C
Santoro
Giuseppe
G
Pacileo
Giuseppe
G
Limongelli
Saverio
S
Scianguetta
Teresa
T
Giugliano
Giulio
G
Piluso
Fulvio Della
FD
Ragione
Mario
M
Cirillo
Giuseppe
G
Mirone
Dipartimento della Donna, del Bambino e di Chirurgia Generale e Specialistica, Second University of Naples, Via Luigi De Crecchio, 4, Naples 80138, Italy. silverio.perrotta@unina2.it.
Silverio
S
Perrotta
D002648:Child; D003937:Diagnosis, Differential; D004452:Echocardiography; D019066:Facies; D006579:Heterozygote; D006801:Humans; D044542:LEOPARD Syndrome / Q000175:diagnosis* / Q000235:genetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009154:Mutation; D017253:Neurofibromatoses / Q000175:diagnosis; D009634:Noonan Syndrome / Q000175:diagnosis; D010641:Phenotype; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000235:genetics
C516724:PTPN11 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11