Osteosarcoma is the most common malignant bone neoplasia affecting individuals in the second decade of life. The survival rate has not been improved during the last 25 years, in part because of the lack of specific markers. The microRNAs have been identified as important regulators of gene expression, experimental evidence suggests these molecules as key players in cancer development and progression. To identify miRNAs differentially expressed in serum from patients with osteosarcoma compared to healthy donors in Mexican population. Fifteen osteosarcoma patients and fifteen age and sex matched healthy individuals were recruited. Two pools of total RNA extracted from serum per study group were prepared and the miRNA expression profiles were analyzed through TaqMan Low Density Arrays. Validation was carried out through RT-qPCR using individual TaqMan assays for those miRNAs differentially expressed. Fifteen miRNAs were differentially expressed in osteosarcoma patients compared to healthy controls. Overexpression of miR-215-5p and miR-642a-5p was confirmed by validation through RT-qPCR. The expression analysis of miRNAs from serum in osteosarcoma patients revealed differential expression of miR-215-5p and miR-642a-5p. Both microRNAs are potential markers for osteosarcoma diagnosis.

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Myositis ossificans is a reactive, ossifying process within soft tissues, which by its clinical and histological features is considered a pseudosarcomatous lesion. There are few reports that describe the cytologic findings in myositis ossificans, and each of these mentions different cellular composition. We describe the cytology of a case of myositis ossificans in a 14-year-old boy with clinical diagnosis of soft tissue sarcoma, and analyze the most common cytologic findings reported previously of this entity. We conclude that the different cellular composition reported, reflects the different histologic components of this lesion according to the area (zonation phenomenon), and that clinico-radiologic correlation is essential for the cytological diagnosis. Diagn. Cytopathol. 2008;36:50-53. ' 2007 Wiley-Liss, Inc.Key Words: myositis ossificans; scrape cytology; cytological diagnosis Myositis ossificans is a reactive, self-limiting condition characterized by prominent heterotopic ossification. It predominantly occurs deep in soft tissues, and in 50% of the cases there is relationship to injury. This lesion passes through several histologic phases. In its early phases a pseudosarcomatous lesion can be mistaken with fibrosarcoma. The intermediate phase characterized by osteoid deposition and the emergence of the zonation phenomenon can be confused with osteosarcoma of soft tissues. The late phase is characterized by the maturation of the lesion with establishment of lamellar bone and marrow fat. 1 We found only seven previous reports 2-8 with emphasis on the cytological findings of this lesion.Our work describes a case of myositis ossificans and analyzes the cytologic findings of previous reports. We make several considerations about the diagnosis by cytology in myositis ossificans. Case ReportA 14-year-old boy was admitted to the National Orthopaedic Institute with a history of progressive pain associated with difficulty in mobilization of the hip and limitation of the march. He started 2 wk earlier, and the initial diagnosis was of a muscular injury. The pain persisted and he was treated with analgesics. There was no history of trauma.Physical examination revealed a 7-cm firm mass located in the right inguinal region associated with pain in this same region. There was a limited range of motion in the right lower extremity. On admission, the X-ray revealed only a slight increase in soft tissues, and the gammagraphy with MIBI showed a high uptake in the lesion.The clinical diagnosis was of a malignant soft tissue tumor. After 19 days an excisional biopsy was made. Macroscopic FindingsThe surgical specimen measured 5.5 3 4 3 3 cm 3 . The lesion was well circumscribed, and it was surrounded by muscle. The margins were sharply defined and were of hard consistency. The cut surface exhibited a gray-white tissue in the central portion that was soft in consistency with focal areas of hemorrhage (Fig. 1A).An X-ray of the surgical specimen revealed a lesion calcified at the periphery (Fig. 1B).

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Background: Primary bone neoplasms are rare, contributing only 0.2% of the global burden of all human malignancies. Osteosarcoma (OS) and chondrosarcoma (CS) are the most common malignancies of bone. The giant cell tumor of bone (GCTb) is a benign tumor with behavior characterized by osteolytic bone destruction. The OS, CS and GCTb affect both sexes, all races and generally have incidence peaks regarding the age of the patient which vary according to the tumor type. We analyzed the incidences of OS, CS and GCTb and their relations with gender and age in patients treated in the National Rehabilitation Institute (INR, for its acronym in Spanish) over a period of nine years. Materials and Methods: In the study period, clinic pathological data for 384 patients were obtained with clinical, radiological and histopathological diagnosis for OS, GCTb and CS. Data analysis was performed using the chi-square and Fisher's exact tests. Results: From 2006 to 2014 were recorded 384 cases of bone malignancies in the database of INR. The GCTb had the highest incidence (53.1%), followed by OS (31.3%) and finally the CS (15.6%). The overall average age was 33.6±15.8 years and the overall frequency of gender had a ratio of 1/1.03 male/female. The states with the highest incidence were Distrito Federal and Estado de Mexico with 29.2% and 25.3% respectively. Malignant neoplasms of bone assessed in the course of nine years show three significant increases in 2008, 2011 and 2014 (p=0.14). We found association between sex and tumor type (p=0.03), GCTb and CS predominated in females (54.9% and 56.6% respectively), while for the OS males were most affected (59.1%). Age was different in relation with tumor type (p=0.0001), average age was 24.3±11.2 years for OS, 34.5±13 years for GCTb and 49.2±18.5 years for CS. Furthermore, associations of tumor type with topographic location of the primary tumor (P=0.0001) were found. Conclusions: In this study we can see that incidence of musculoskeletal tumor in our population is continuously increasing and in nine years an approximately 200% increase of musculoskeletal tumor cases was observed.