Bernard-Soulier syndrome is a very rare autosomal recessive disorder of impaired clotting. Depending on the phenotype, patients present with bleeding episodes of variable severity. Epistaxis, cutaneous hemorrhage, pronounced post-traumatic bleeding, and severe menorrhagia are typically encountered. Certain cases could manifest with post-procedural bleeding. Thrombocytopenia, very large platelets, and a prolonged skin bleeding time are some of the main findings, but genetic studies and the use of techniques that examine the platelet expression of surface glycoproteins are necessary to confirm the diagnosis.
Bernard-Soulier syndrome is a rare inherited disorder of coagulation, with only about 100 cases reported and prevalence rates of less than 1 in 1,000,000 individuals    . The pathogenesis stems from autosomal recessive mutations that cause a deficiency of receptors located on the surfaces of platelets    . Specifically, the deficiency of the glycoprotein (GP) Ib-IX-V complex impairs the binding of von Willebrand factor (VWF), ultimately resulting in an insufficient coagulatory response     . The clinical presentation of Bernard-Soulier syndrome strongly depends on the extent of mutations, ranging from asymptomatic and mild (typical for heterozygotes) to severe and life-threatening (characteristic for homozygous individuals )     . Symptoms appear as early as in infancy and childhood, with main findings being epistaxis, gingival bleeding, purpura, trauma-associated hemorrhage, and pronounced cutaneous bruising   . Post-procedural bleeding (for example after tonsillectomies, dental procedures, appendectomies, splenectomies, etc.) is an important manifestation in patients with more severe phenotypes, whereas hematuria and gastrointestinal bleeding are less common presentations   . In women, excessive menorrhagia is a common manifestation   .
The diagnosis of Bernard-Soulier syndrome might be difficult to attain, primarily because of the very rare occurrence of this disorder. For this reason, the physician must conduct a detailed patient history that determines the onset and progression of symptoms, followed by a physical examination. As soon as suspicion of a coagulation disorder is raised, laboratory studies need to be employed. A complete blood count (CBC) with a peripheral blood smear can provide vital clues toward a more specific diagnosis   . Thrombocytopenia, although being variable from patient to patient, is virtually always present, and is accompanied by the appearance of very large platelets that may sometimes resemble lymphocytes  . In fact, some authors recommend manual counting of these large platelets, as they are often mistaken as lymphocytes by automatic counters . In addition to these findings, prolonged skin bleeding time is also a constitutive feature of Bernard-Soulier syndrome  . However, more advanced studies that assess the surface glycoproteins on platelets, such as flow cytometry, immunoblotting, and surface-labeling of washed platelets, but also VWF assessment, are sometimes necessary to solidify the diagnosis   . Molecular genetic testing serves as a definitive diagnostic method  .