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Background Lymphedema is an abnormal accumulation of interstitial fluid within the tissues. Primary lymphedema is caused by aberrant lymphangiogenesis and it has been historically classified based on age at presentation. Although most cases are sporadic, primary lymphedema may be familial or present in association with chromosomal abnormalities and syndromic disorders. To the best of our knowledge, primary lymphedema has never been described in patients with 22q11.2 deletion syndrome. Methods and results We identified 4 patients with 22q11.2 deletion syndrome and primary lymphedema via our International 22q11.2 Deletion Syndrome Consortium. All patients underwent comprehensive clinical, laboratory and imaging assessments to rule out other causes of lymphedema. All patients had de novo typical deletions and family histories were negative for lymphedema. Conclusions We report the novel association of primary lymphedema with 22q11.2 deletion syndrome. Importantly, animal models demonstrated Tbx1 playing a critical role in lymphangiogenesis by reducing Vegfr3 expression in lymphatic endothelial cells. Moreover, the VEGFR3 pathway is essential for lymphangiogenesis with mutations identified in hereditary primary lymphedema. Accordingly, our findings provide a new insight into understanding cellular mechanisms of lymphangiogenesis disorders.

Purpose Optic pathway gliomas (pilocytic astrocytomas) in neurofibromatosis type 1 (NF-1) typically involve some combination of the optic nerves, chiasm, or optic tracts. Involvement of the optic radiations is rare. Design This paper describes seven patients with NF-1 with gliomas involving the pregeniculate optic pathway in addition to the optic radiations. Methods A retrospective database review was made of all patients with NF-1 and optic pathway gliomas seen by one of the authors (G.T.L.) at the Children's Hospital of Philadelphia from July 1993 to October 2001. Patients with involvement of pregeniculate optic pathway and the optic radiations were identified. From November 2001 to February 2003, patients were sought prospectively. Cases were also identified from the practice of another author (M.C.B.) at Arkansas Children's Hospital. Results Four patients from Children's Hospital of Philadelphia (three of 83 total NF-1/optic pathway gliomas from July 1993 to October 2001 and one prospectively) and three from Arkansas Children's Hospital were identified. Two had expanding mass lesions within the white matter of the temporal or parietal lobes, which were histopathologically demonstrated to be pilocytic astrocytomas. The other five had radiographic involvement of the optic radiations but did not undergo biopsy. In three of the cases the vision was 20/200 or worse in each eye. Conclusions Optic pathway gliomas in NF-1 may rarely involve the optic radiations. Optic radiation involvement may signal a more aggressive optic pathway glioma in patients with neurofibromatosis-1.