Background A giant congenital melanocytic nevus (GCMN) is found in 0.1% of live-born infants. If present, the lesion has a chance of about 6% to develop into malignant melanoma. Both children and adults can be affected by malignant melanoma arising in a giant congenital nevus. Up to 95% of GCMNs harbor NRAS mutations, and mutations in the BRAF , MC1R , TP53 , and GNAQ genes have also been described. The individualization of therapy is required, but diagnostic and prognostic criteria remain controversial. Case presentations We report two cases: 1) melanoma arising in a giant congenital nevus during the first month of life complicated with neurocutaneous melanosis (NCM), and 2) melanoma arising in a giant congenital nevus during the first 6 months of life. Pathology, immunohistochemistry, and genetic analyses of tumor tissue were performed. The first case revealed only a non-pathogenic P72R polymorphism of the TP53 gene in the homozygote condition. For the second case, a Q61K mutation was detected in the NRAS gene. Conclusion Malignant melanoma associated with GCMN is rare and therefore poorly understood. Outcomes have been linked to the stage at diagnosis, but no additional pathological prognostic factors have been identified. The most frequent genetic event in giant CMNs is NRAS mutations, which was discovered in one of our cases. To accumulate evidence to improve disease prognosis and outcomes, children with congenital melanocytic nevus should be included in a systemic follow-up study from birth.

Data from 44 patients (23 males, 21 females) with a median age of 39 (range 13-80) years who underwent total hip arthroplasty for proximal femoral tumours (1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) were analysed. The histological diagnoses included 14 metastases, six osteosarcomas, six chondrosarcomas, four Ewing's sarcomas, four giant cell tumours, three malignant fibrous histiocytomas, two parosteal and two periosteal osteosarcomas, and one each primary neuroectodermal tumour, myeloid disease, and aneurysmal bone cyst. Twenty-one patients (48%) had pathological fractures. The cause of the pathological fracture was metastasis in 12 patients (57%). Twenty-eight patients (64%) had soft tissue invasion. Complications observed in 17 patients (37%) were local recurrence in two, postoperative haematoma in two, dislocation of prosthesis in five, deep infection in six, and one patient died of myocardial infarction in the early postoperative period. During our midterm survival analysis, functional results were excellent in 25% of patients, good in 57%, fair in 12%, and poor in 6%.Résumé Entre 1994 et 2004, nous avons récolté les données de 44 patients (23 hommes et 21 femmes), dont l'âge moyen était de 39 ans (de 13 à 80), qui ont bénéficié d'une prothèse totale de hanche pour une tumeur de l'extrémité proximale du fémur 4. Le diagnostic étiologi-que a inclus, chez ces patients, 14 métastases, 6 ostéosarcomes, 6 chondrosarcomes, 4 sarcomes d'Ewing, 4 tumeurs à cellules géantes, 4 histiocytomes malins, 2 sarcomes paraosteal, 2 sarcomes périosters et une tumeur neuroectodermique, un myélome un kyste anévrismal. 21 patients (48%) présentaient une fracture pathologique. La fracture pathologique était une métastase chez 12 patients (soit 57%). Pour 28 patients (64%) avaient un envahissement des parties molles. Des complications ont été observées chez 17 patients (37%) avec 2 récidives locales de la tumeur, 2 hématomes post-opératoires, 5 luxations de prothèse, 6 infections profondes et un patient décédé d'infarctus du myocarde en post opératoire précoce. Le résultat fonctionnel a été noté excellent à moyen terme chez 25 patients, bon chez 57%, moyen pour 12% et mauvais pour 6% des patients.

Association study of 6 candidate single-nucleotide polymorphisms (rs7921, rs7956547, rs3761243, rs11737764, rs6599400, rs1690916) was carried out in a group of patients with bone tumors of different histological structure (n=68) and control group of normal subjects (n=96). Significant associations of rs6599400 and rs1690916 polymorphisms with disease risk were detected (odds ratio 2.15 [1.06-4.24] and 0.39 [0.19-0.78], respectively). These polymorphisms were located in untranslated genome regions: polymorphism rs6599400 in the 5' region of fibroblast growth factor-3 receptor gene (FGFR3), rs1690916 in the 3' region of mouse MDM2 p53-binding protein homolog (MDM2). These data indicated a possible role of hereditary genetic factors in the formation of predisposition to bone sarcomas and confirmed previous findings according to which these genes should be regarded among the most probable factors involved in tumor development, including tumors of the bone and cartilage tissues.

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