Although rare, MPNST is one of the most aggressive tumors in the head and neck area. Complete tumor removal is the mainstay of treatment and most important prognostic factor of MPNST. Adjuvant radiotherapy should be used to assist surgical excision in local control. The role of adjuvant chemotherapy remains controversial.

Concerning response to treatment and overall prognosis, all patients experienced a complete response to induction therapy with rapid decrease in leukocytosis and resolution of extramedullary involvement under corticosteroid therapy. MRD, when applicable, was found negative at the end of induction, underlying high sensitivity to chemotherapy. This high chemosensitivity contrasted with the high incidence of relapse (occurring in three of our cases) and poor overall prognosis. This finding underlines the importance of quick identification of this rearrangement to propose treatment adaptation to high-risk groups, including allogeneic marrow transplantation consideration before facing potentially chemoresistant relapse.In summary, we describe here five cases of mature 'sIg þ ' B-ALL with non FAB-L3 morphology displaying 11q23-MLL rearrangement, and especially t(9;11), occurring in young children with a poor prognosis and requiring treatment intensification.

The AC method is the method of choice for accurate LN staging in locally advanced rectal cancer, especially after preoperative RCT, and is well suited for routine gastrointestinal pathology workup.

Extraosseous osteosarcomas are very rare malignant neoplasms that have been published in 300 cases so far. Manifestation within the thyroid gland was described in 6 cases only. We report a 69 year old female who suffered from enlarged recurrent struma after primary resection and radiotherapy 5 years ago. Histology revealed a high grade extraosseous osteosarcoma. Presenting the patient's clinical, radiological and histological findings the therapeutical options of this rare tumor entity are discussed.

Leser-Trélat-syndrome is characterized as the eruptive appearance of multiple seborrheic keratoses in association with underlying malignant disease. A 73 year old female patient with a metastatic adenocarcinoma of the colon presented with this paraneoplastic change. The rapid appearance of solitary seborrheic keratoses with associated inflammation, seen clinically and histologically, may be an early sign of Leser-Trélat-syndrome. The recognition of this inflammatory component as an early sign may contribute to the prompt diagnosis of this paraneoplasia, even before the eruption of numerous seborrheic keratoses.