A vestibular schwannoma in a patient with Birt-Hogg-Dube syndrome.

Birt-Hogg Dubé syndrome is an autosomal dominant disease with variable clinical expression. It is characterized by cutaneous manifestations, renal tumors and lung cysts. Other tumors, such as adrenal tumors and tumors originating from the neural crest cells such as meningioma and neurothekeoma have also been described. This syndrome is caused by germline mutations in the folliculin (FLCN) gene located on chromosome 17p. We report, for the first time, a patient with BHDS and a history of a vestibular schwannoma in adolescence. The diagnosis of BHDS was confirmed, by identifying a nonsense mutation in exon 10 of the FLCN gene. A vestibular schwannoma also originates from neural crest cells, just as other neural tumors, previously encountered in patients with BHDS. The reported mutations cause a truncation of the protein, folliculin. The exact role of folliculin is still undetermined. Two different theories suggest the effect of tumorigenesis. One is that folliculin plays an important role in the AMPK-mTOR pathway which leads to proliferation of cells when activated. The other is that the folliculin acts as a possible tumor suppressor gene, since there is a high frequency of second hits in the FLCN-gene. In order to confirm a possible relation of BHDS and neural crest tumors, further research is necessary in the tumorigenesis of the folliculin gene.

Pseudo-Kaposi's sarcoma as a complication of Cimino-Brescia arteriovenous fistulas in hemodialysis patients.

Pseudo-Kaposi's sarcoma is a skin lesion that is associated with chronic venous insufficiency and/or congenital arteriovenous fistulas. Theoretically, this lesion could also be expected in connection with hemodialysis vascular accesses. Nevertheless, this disease has been reported only once in conjunction with a Cimino-Brescia arteriovenous fistula, and no attention has been paid to the potential complications of this disease. In the present paper 3 cases are reported. In 1 patient pseudo-Kaposi's sarcoma was complicated by an infected open wound as a consequence of a trauma. In the 2 other patients, a skin biopsy was followed by local infection and retarded healing of the wound. Evaluation by fistulagraphy and/or Doppler revealed venous outflow stenosis in only 1 case. After reconstruction or ligation of the fistula, correction of the lesions was observed. It is concluded that pseudo-Kaposi's sarcoma can occur as a complication of Cimino-Brescia arteriovenous fistulas, necessitating early correction of the fistula. The performance of a skin biopsy might be associated with infection and delayed wound healing, so that this diagnostic procedure should only be performed in cases where the clinical diagnosis is not obvious.