Rare tumors in pediatric age group: Single center experience from Saudi Arabia.

Rare pediatric tumors are heterogeneous group containing a variety of histopathological diseases, they represent approximately 10% of all childhood cancers. These rare tumors had a diversity of histology and clinical behaviors that pose different challenges to the investigators. Exploring different pediatric rare tumors. The data were reviewed, retrospectively, through the medical records of seven rare pediatric diseases between 2012 and 2019. Giant cell fibroblastoma (GCF) presented as painless swelling in the trunk, positive for CD34 with PTEN gene mutation. Neuroglial heterotopic tissue presented in 7 days old girl with facial asymmetry and bulging in the oral cavity, maximal de-bulking was done, histopathology was positive for GFAP and S100p. Left side neck mass, surgically excised revealed non-metastatic salivary grand mucoepidermoid carcinoma. Follow up without any chemotherapy or radiotherapy for 5 years with complete remission. Mesenchymal chondrosarcoma (MCS) presented in maxillofacial bones by persistent nasal bleeding, HEY1-NCOA2 fusion gene confirmed the diagnosis. Extra-osseous Ewing sarcoma (EES) presented as rubbery painless swelling in the scalp with fusion transcript involving EWSR1-FL11. Juvenile xanthogranuloma (JXG) presented by butter fly like skin patch in the face with foamy histiocytes in upper dermis with few Touton giant cells, extensive systemic involvement of lung and bone marrow. Metastatic ovarian choriocarcinoma with choriocarcinoma syndrome received induction two different lines of chemotherapy and consolidated with autologous stem cell transplant. Seven pediatric rare tumors, with different aspects of challenges in diagnosis and management, despite the absence of formal protocols and rarity of other center experiences.