Primary osteochondrorhabdomyosarcoma (malignant mesenchymoma) of the fibula: a rare tumour in an unusual site - Case report and review of the literature. Case report

Composite sarcoma of bone with focal rhabdomyosarcoma and lymph node metastasis in an adolescent

Composite sarcoma of bone is a very rare entity that primarily affects adolescent and young adult patients. It usually combines areas of liposarcoma and osteosarcoma, and up to 60% of cases have metastatic disease at diagnosis. It is a highly aggressive pathology with intrinsic resistance to bone sarcoma conventional treatments. The prognosis is poor, with long-term survival rates not exceeding 30%. We present the case of an adolescent female diagnosed with an aggressive composite sarcoma of bone with rhabdomyosarcoma foci and loco-regional lymph node involvement.

CNS Metastases from Bone and Soft Tissue Sarcomas in Children, Adolescents, and Young Adults: Are They Really So Rare?

Purpose. To check whether primary involvement of brain/spinal cord by bone/soft tissue sarcomas' metastases in children is as rare as described and to present various morphological forms of bone/soft tissue sarcomas' CNS metastases. Methods. Patients with first diagnosis in 1999–2014 treated at single center were included with whole course of disease evaluation. Brain/spinal canal magnetic resonance imaging (MRI)/computed tomography were performed in cases suspicious for CNS metastases. Extension from skull/vertebral column metastases was excluded. Results. 550 patients were included. MRI revealed CNS metastases in 19 patients (incidence 3.45%), 14 boys, aged 5–22 years. There were 12/250 osteosarcoma cases, 2/200 Ewing's sarcoma, 1/50 chondrosarcoma, 3/49 rhabdomyosarcoma (RMS), and 1/1 malignant mesenchymoma. There were 10 single metastases and 7 cases of multiple ones; in 2 RMS cases only leptomeningeal spread in brain and spinal cord was found. Calcified metastases were found in 3 patients and hemorrhagic in 4. In one RMS patient there were numerous solid, cystic, hemorrhagic lesions and leptomeningeal spread. Conclusions. CNS metastases are rare and late in children with bone/soft tissue sarcomas, although in our material more frequent (3.45%) than in other reports (0.7%). Hematogenous spread to brain and hemorrhagic and calcified lesions dominated in osteosarcoma. Ewing sarcoma tended to metastasize to skull bones. Soft tissue sarcomas presented various morphological forms.

Malignant mesenchymal tumor with leiomyosarcoma, rhabdomyosarcoma, chondrosarcoma, and osteosarcoma differentiation: case report and literature review

A case of malignant mesenchymoma of the bladder containing leiomyosarcoma, rhabdomyosarcoma, chondrosarcoma, osteosarcoma, and myxomatous components is described. The primary pedunculated tumor measuring 14 × 13 × 7 cm and weighing 343 g arose from the left trigone of the bladder and was treated by total cystectomy. The histogenesis of malignant mesenchymomas and their optimal management strategy and prognosis remain uncertain. Herein, we present the fifth case of malignant mesenchymoma of the urinary bladder to be reported in the literature, which presented five unrelated differentiated tissues more than did previously reported cases.

Primary osseous rhabdomyosarcoma with focal matrix formation mimicking osteosarcoma

We present an unusual case of primary osseous pleomorphic rhabdomyosarcoma with focal matrix formation mimicking osteosarcoma. The patient was a 21-year-old man who had suffered from pain and slight enlargement of his left calf for 2 months. A plain radiograph demonstrated a large, predominantly osteolytic mass in the region of the proximal fibula with features typical of malignant primary bone tumor. On open surgical biopsy, the tumor consisted of atypical cells, some of them presenting spindle morphology. Between them, there were bands of densely hyalinized matrix with osteoid appearance, but without definite lacunae or calcifications, and an osteosarcoma was diagnosed. Consequently, the tumor was removed. The postoperative tissue presented more pleomorphic cells with some definite rhabdomyoblasts. Desmin, actin, Myf4, and MyoD1 were positive in tumor cells, and a diagnosis of rhabdomyosarcoma was eventually made. Only few cases of primary pure bone rhabdomyosarcoma have been reported. Other bone tumors with rhabdomyosarcomatous differentiation have been described: dedifferentiated chondrosarcoma, fibrosarcoma, and osteosarcoma. Our case does not meet the criteria for sclerosing rhabdomyosarcoma, as matrix formation is focal and cells are spindle-shaped and pleomorphic. However, it is a further example of a diagnostic error in connection with primary osseous tumor.

Postirradiation osteosarcoma of the mandible with heterologous differentiation

Heterologous differentiation in osteosarcoma is rare, with only 17 cases previously described in the literature. We report a case of a mandibular osteoblastic osteosarcoma with rhabdomyosarcomatous differentiation in a 45-year-old man who had a history of Hodgkin lymphoma that was treated with chemotherapy and radiation. Radiographs showed a destructive osteoblastic tumor of the mandible that was proven by biopsy to be osteosarcoma. After the patient underwent neoadjuvant chemotherapy, the tumor was resected. It contained a high-grade osteosarcoma composed of osteoblastic and chondroblastic elements that had no definitive response to therapy. Within the center of the lesion was a discrete focus of pleomorphic cells with rhabdomyosarcomatous differentiation that was confirmed by immunohistochemical stains for desmin, myogenin, and myogenic differentiation antigen 1. The patient received additional chemotherapy and radiation therapy but developed lung, brain, and spinal metastases and died 7 months after surgery. To our knowledge, this is the first report of osteosarcoma of the mandible with heterologous differentiation.

Association of the t(12;22)(q13;q12) EWS/ATF1 rearrangement with polyphenotypic round cell sarcoma of bone: a case report

The t(12;22)(q13;q12) chromosomal rearrangement results in an EWS/ATF1 fusion transcript and is associated with clear cell sarcoma (CCS). CCS is an uncommon tumor arising in tendons and aponeuroses of the extremities and shows evidence of melanocytic differentiation at the light microscopic, immunohistochemical, and/or ultrastructural level. Only 5 cases have been reported to arise in bone, none of which had molecular confirmation of the diagnosis. The current report describes a 7-year-old girl with a primary round cell sarcoma of the left humerus showing polyphenotypic differentiation on immunohistochemical analysis. Antibodies directed at melanocytic antigens were negative, and there was no evidence of melanocytic differentiation by light microscopy or ultrastructural analysis. Cytogenetic analysis revealed rearrangement of the EWS locus within 22q12. RT-PCR and sequence analysis revealed the presence of a fusion transcript bringing together exon 7 of EWS with exon 5 of ATF1, consistent with a type 2 transcript reported in association with CCS. However, given the lack of morphologic features usually present in CCS, a diagnosis of polyphenotypic round cell sarcoma was made. This tumor thus expands the spectrum of neoplasms associated with the t(12;22)(q13;q12) rearrangement.