Melanoma in Noonan Syndrome With Multiple Lentigines (Leopard Syndrome): A New Case

Melanoma and LEOPARD Syndrome: Understanding the Role of PTPN11 Mutations in Melanomagenesis

Abstract is missing (Short communication)

Dermatological manifestations, management, and care in RASopathies

RASopathies are rare genetic disorders caused by germline pathogenic variants in genes belonging to the RAS/MAPK pathway, which signals cell proliferation, differentiation, survival and death. The dysfunction of such signaling pathway causes syndromes with overlapping clinical manifestations. Skin and adnexal lesions are the cardinal clinical signs of RASopathies, such as cardiofaciocutaneous syndrome, Noonan syndrome with multiple lentigines, formerly known as LEOPARD syndrome, Costello syndrome, neurofibromatosis (NF1), Legius syndrome, Noonan-like syndrome with loose anagen hair (NSLH) and Noonan syndrome. As NF1, one of the most common RASopathies, described in 1882, has its clinical features well delineated, we will focus on the dermatological diagnosis, management and care of non-NF1 RASopathies, which are less known and more recently described. Dermatological manifestations are important clinical diagnostic elements that can aid differential diagnosis among RASopathies. They can affect dermis and epidermis, causing pigmented lesions (melanocytic nevi, café-au-lait spots, and lentigines), hyperkeratosis (keratosis pilaris, ulerythema ophryogenes, and palmoplantar keratosis) or hyperplasia. To date there are rare known links to malignancy, but oftentimes skin lesions require close attention because they can highly affect quality of life.

Leopard syndrome: the potential cardiac defect underlying skin phenotypes

LEOPARD syndrome (OMIM #151,100) caused by a germline PTPN11 mutation are characterized as multisystemic anomalies and variable marked phenotypes such as multiple lentigines and cafe´-au-lait spots, electrocardiographic conduction abnormalities, ocular hypertelorism/obstructive cardiomyopathy, pulmonary stenosis, abnormal genitalia, retardation of growth, and deafness. Phenotype overlap complicates clinical discrimination within RASopathies, making the diagnosis of LEOPARD more confusing and challenging. Besides, LEOPARD patients do not usually present with all these typical clinical features, increasing the possibility of underdiagnosis or misdiagnosis.

Herein, we report a case of LEOPARD syndrome in a patient who only presented with pigmented skin spots and was initially diagnosed with multiple acquired melanocytic nevi. Subsequent pathological examination confirmed the diagnosis of multiple lentigines rather than melanocytic nevi. A genetic study showed a germline PTPN11 (Tyr279Cys) mutation and raised the suspicion of LEOPARD syndrome. A subsequent ECG examination detected potential cardiac defects and confirmed the diagnosis of LEOPARD. We considered that the potential damage of other systems underlying the skin multiple lentigines should not be ignored. The diagnosis of LEOPARD syndrome in an early stage before cardiac damage has reached a serious and irreversible stage can be meaningful for patients to fully understand the potential risks, complications and prognosis of the disease and to take appropriate precautions to prevent the potential risk of cardiac damage.