Preclinical Evidence for the Use of Sunitinib Malate in the Treatment of Plexiform Neurofibromas.

Purpose: Plexiform neurofibromas (pNF) are pathognomonic nerve and soft tissue tumors of neurofibromatosis type I (NF1), which are highly resistant to conventional chemotherapy and associated with significant morbidity/mortality. Disruption of aberrant SCF/c-Kit signaling emanating from the pNF microenvironment induced the first ever objective therapeutic responses in a recent phase 2 trial. Sunitinib malate is a potent, highly selective RTK inhibitor with activity against c-Kit, PDGFR, and VEGFR, which have also been implicated in the pathogenesis of these lesions.

Nf1-dependent tumors require a microenvironment containing Nf1+/-- and c-kit-dependent bone marrow.

Interactions between tumorigenic cells and their surrounding microenvironment are critical for tumor progression yet remain incompletely understood. Germline mutations in the NF1 tumor suppressor gene cause neurofibromatosis type 1 (NF1), a common genetic disorder characterized by complex tumors called neurofibromas. Genetic studies indicate that biallelic loss of Nf1 is required in the tumorigenic cell of origin in the embryonic Schwann cell lineage.

Spindle cell lipoma of the oral cavity.

Spindle cell lipoma is typically seen in the neck/trunk region of middle-aged and older men. Rare cases of oral spindle cell lipoma have been reported. An entity described as myxoid lipoma of the oral cavity has rarely been reported but appears to be more properly classified as spindle cell lipoma.

Disseminated toxoplasmosis resulting in graft failure in a cord blood stem cell transplant recipient.

Toxoplasmosis is an infrequent infection with a high mortality rate in hematopoietic stem cell transplant recipients, and is usually caused by reactivation of prior, latent infection upon intensive immunosuppression. We report a case of fatal disseminated toxoplasmosis, diagnosed at autopsy, in a 7-year-old boy who received a cord blood graft for recurrent acute lymphoblastic leukemia. This case represents both the first reported case of toxoplasmosis in an engrafted cord blood recipient, and also of graft failure due to toxoplasmosis.