Images of the month 2: A leopard never changes its spots

Approximately 200 cases of multiple lentigines syndrome have been documented with approximately 90% exhibiting a PTPN11 mutation.1 In its inherited form, it is an autosomal dominant condition where cutaneous features commonly manifest in childhood.1 Although the acronym of clinical signs are commonly seen, it is extremely heterogeneous in both spectrum of disease and severity. There are several other associations in the spectrum of this disease that fall outside of the confines of the acronym including syndactly, which our patient also demonstrated.2 PTPN11 is found at chromosomal position 12q24.13, of which to date 11 mutations have been identified as a cause of multiple lentigines syndrome.3 Most of these mutations result in a change in a single amino acid for the SHP-2 protein, disrupting its function.4 A decrease in SHP-2 function impairs the activation of the ras/mitogen-activated protein kinase signalling pathway, which controls cell functions such as growth and division but also melanin synthesis in melanocytes.3 This dysregulation can result in these various features of LEOPARD syndrome and is thus a rasopathy.3 Although PTPN11 is an oncogene, a reduction in the protein's function does not seem to increase skin cancer risk although there is concern over its link to leukaemia and, more recently, solitary granular cell tumours.4,5 This case demonstrates how taking a broad view of one's examination can ultimately reveal plentiful positive clinical signs. Furthermore, a keen eye and consideration of prompt genetic screening can result in unexpected diagnoses of rare genodermatosis and appropriate multidisciplinary management. -