| BACKG ROU N D
Klippel-Trenaunay syndrome (KTS) is a rare congenital disorder defined by the classic triad of capillary malformations, venous malformations with or without lymphatic malformations and limb overgrowth. [1] [2] [3] Although the diagnosis of KTS is mostly based upon the evidence of the key clinical features, laboratory and imaging studies may be crucial for further characterization of the extent of disease and the presence of complications. 3 The management of individuals with KTS should be individualized and involve a multidisciplinary medical and surgical approach.
| BACKG ROU N D
Acanthocytes are hyperchromic red blood cells (RBC) that exhibit 2-20 irregularly spaced thorn-like spicules of variable length, thickness and shape, frequently with drumstick ends. [4] [5] [6] Since the integrity of RBC membrane, which consists of a lipid bilayer, a set of transmembrane proteins and a cytoskeleton, depends on proteinprotein and protein-lipid molecular interactions, 7 the mechanism of acanthocyte formation is probably linked to abnormalities in the protein or lipid composition of this structure. [4] [5] [6] Acanthocytes are rarely seen in otherwise normal peripheral blood films but, in those circumstances, they correspond to older senescent RBC. [4] [5] [6] The aim of this short report is to describe the case of a Portuguese young man with KTS and marked (3+) acanthocytosis with no other aetiological cause.
| C A S E REP ORT
A 21-year-old Portuguese young man was diagnosed with KTS in the first month of life and he has been followed in our tertiary In spite of the presence of mild peripheral blood cytopenias, the bone marrow cells morphology did not show dysplastic changes or increased apoptosis, so the hypothesis of myelodysplastic syndrome was also excluded.
| D ISCUSS I ON
In the early twentieth century, Klippel and Trenaunay described a rare congenital mesodermal disorder 1 which, over the years, has as- to our best knowledge, there is only one case report in the medical literature on KTS presenting with acanthocytosis. 8 Throughout the follow-up period, although the wide range of diagnostic tests failed to identify an aetiological cause for the abnormal RBC morphology, our patient kept a marked (3+) acanthocytosis, which makes it plausible to consider that this condition can be primarily related to his underlying disease; however, despite KTS may play an important role in the pathogenesis of acanthocytosis, the exact mechanism of this relationship is still uncertain.
| CON CLUS ION
The recognition of the association between KTS and acanthocytosis may avoid unnecessary investigations in such patients and, thus, reduce the economic burden associated with additional diagnostic tests. In the light of current medical knowledge, it is still impossible to state whether this association will alter the management and/or the prognosis of this syndrome, so it is essential to establish the accurate incidence and prevalence of acanthocytosis in individuals with KTS and to recognize the underlying mechanism of this correlation.
D I S CLOS U R E A N D CO M PE TI N G I NTE R E S T S S TATEM ENTS
All authors disclose neither personal financial interests nor specific funding from organizations that might benefit through publication of the manuscript. 
AUTH O R CO NTR I B UTI O N

PU B LI C ATI O N E TH I C S
Patients' written consent was obtained and it is available from the corresponding author on request. 
DATA S H A R I N G A N D ACCE SS I B I LIT Y


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