Cancer Risk in Klippel-Trenaunay Syndrome.

Background: Klippel-Trenaunay syndrome (KTS) is an overgrowth syndrome defined by capillary/venous/lymphatic malformations (CVLM) with soft tissue and/or bone hypertrophy. Whether KTS predisposes to cancer is not clear. Methods and Results: We surveyed members of the K-T Support Group (KTSG) and reviewed PubMed for "Klippel Trenaunay Syndrome" or "CVLM" and "cancer." Individuals with cancer were reviewed for confirmation of KTS, tumor type, location, and age at presentation. Of 223 KTSG respondents, 24 (10.8%) reported 26 malignancies or benign brain tumors (diagnosed from 6 months to 68 years of age, median 41 years), including 3 who were younger than 18 years (2 with Wilms tumor). Nine of twenty-six cancers were basal cell carcinomas (4% of respondents). From 475 articles, we identified 11 cancers or brain tumors in 10 individuals with KTS. Four of these were in children (Wilms tumor n = 2; rhabdomyosarcoma n = 1; serous borderline tumor n = 1). Tumors in adults included basal cell carcinoma (n = 1), squamous cell carcinoma of skin (n = 2), and angiosarcoma, Hodgkin disease, glioblastoma, malignant hemangiopericytoma in one patient each. Ulceration or lymphedema associated with VLM or capillary malformations were associated with some basal cell or squamous cell carcinomas and angiosarcomas. Conclusions: The risk of embryonal cancer other than Wilms tumor in children with KTS does not appear to be higher than in the general population. Wilms tumor incidence is under 5%, and routine surveillance is not indicated. In adults, particular attention should be paid to skin in the area of malformations. These conclusions may not apply to all overgrowth syndromes with vascular malformations.