Small cell osteosarcoma of the soft tissue

Clarifying prognostic factors of small cell osteosarcoma: A pooled analysis of 20 cases and the literature

Introduction

Small cell osteosarcoma (SCOS) is a rare subtype of osteosarcoma, with limited studies mainly focusing on histological features. Our study aims to analyze our own patients and those reported in the literature to increase the recognition of this rare disease, to evaluate patient survival and to further determine potential prognostic factors.

Material and methods

Twenty patients with SCOS were treated in our hospital between 2010 and 2019. Their follow-up data were collected retrospectively. A total of 336 literature cases from 58 manuscripts were retrieved by means of a PubMed search with the key word “small cell osteosarcoma”. Data pertaining to treatment and follow-up were extracted. We performed a pooled analysis for the survival of patients and the risk factors for local recurrence (LR), as well as metastatic disease (MD), in a total of 160 patients using the Kaplan-Meier method and Cox regression method.

Results

We reported our experience in diagnosing and treating SCOS. In our cases, elevated alkaline phosphatase (P = 0.013) and lactate dehydrogenase (P = 0.001) significantly impaired overall survival. In the pooled analysis, SCOS was diagnosed at the median age of 17 years and affected both sexes almost equally. The median follow-up duration was 19.5 months. In the pooled analysis cases, the 5-year overall survival rate was 38.6%, and 36.4% of patients survived 10 years. However, an increasing trend was detected, indicating recent improvements in management. The surgical margin status (P = 0.024) and metastases (P = 0.008) significantly impaired overall survival, and the response to chemotherapy was related to disease-free survival (P = 0.012). LR and MD were significantly correlated (P = 0.002) and could be observed after 5 years of follow-up. LR was significantly dependent on response to chemotherapy (P = 0.020). The development of MD seemed to be affected by response to chemotherapy (P = 0.060). Correlations between imaging features and prognosis were not detected.

Conclusions

This study suggested that positive margins, poor response to chemotherapy and MD are negative prognostic factors for SCOS, implied the potential role of laboratory examinations in the survival prediction and supported the need for prolonged or more intensive surveillance in patients with MD or LR. More well-documented literatures are encouraged to allow further confirmations.

Contralateral referred pain in a patient with intramedullary spinal cord metastasis from extraskeletal small cell osteosarcoma

CONTEXT

Referred pain has been observed in some patients after cordotomy, wherein noxious stimulus applied to a region rendered analgesic by cordotomy produces pain at a spot different from the one where the noxious stimulus is applied. We report a patient who had intramedullary spinal cord metastasis of extraskeletal small cell osteosarcoma, a rare form of metastatic disease, and experienced contralateral referred pain.

FINDINGS

Initially, the patient had a mass in the left posterior neck region and later developed a large extradural mass at the C3-C7 level. The masses were excised, and the histological findings led to a diagnosis of small cell osteosarcoma. He underwent chemotherapy and radiation therapy. He experienced numbness in his left leg; subsequently, the numbness slowly spread up the thigh to the left side of the abdomen. When pinched in the numb area on the left side of the body, he felt as though he had been pinched in both that area and the corresponding area on the right side. A magnetic resonance imaging scan showed an enhancing lesion in the right side of the cord at the C6-C7 level.

CONCLUSION/CLINICAL RELEVANCE

An intramedullary spinal cord metastasis can arise from primary extraskeletal small cell osteosarcoma and cause contralateral referred pain, especially in a mirror-image location. Contralateral referred pain may be caused by a subsidiary pathway comprising ascending chains of short neurons that link the dorsal horn neurons longitudinally and latitudinally.

Small cell osteosarcoma of the mandible: Case report and review of its diagnostic aspects

Small cell osteosarcoma, a rare histological subtype, has very infrequently been reported in the mandible. We present a case of a 28-year-old female who had classic signs, symptoms, and radiographic features of the lesion. The histology showed sheets of small round cells and osteoid. The absence of the latter would have made it difficult to distinguish from other small round cell tumors of bone, especially Ewing's sarcoma. We have reviewed the clinical and radiographic features, cytologic and histologic characteristics, as well as the immunohistochemistry and molecular genetics of small cell osteosarcoma.

Small cell tumors of bone

Bone tumors are fortunately rare, but small cell tumors of bone are a relatively common subset of these lesions. They comprise of a diverse group of primary and metastatic neoplasms in both children and adults. The most common small cell tumors of bone include Ewing sarcoma/primitive neuroectodermal tumor, small cell osteosarcoma, multiple myeloma, lymphoma, leukemia, neuroblastoma, rhabdomyosarcoma, and Langerhans cell histiocytosis. Although each entity has its distinctive features, the differential diagnosis of this group of tumors is still challenging because they are all "small, blue, and round cell tumors", histologically. The correct diagnosis of small cell tumors of bone depends on an evaluation of clinical, radiologic, pathologic, and genetic features. Patients' age and sex are very important, as are the signs and symptoms at presentation. Radiologically, which bone is involved, the specific portion of the bone (epiphysis, metaphysis, or diaphysis; cortex vs. medulla) involved, and the radiographic manifestations (lytic, blastic, or mixed lytic and blastic) are also often critical parameters for the diagnosis. In recent years, with a better understanding of the molecular and cytogenetic background of several small cell tumors, more accurate diagnoses have been supported by the clinicopathologic criteria and by a panel of immunohistochemical studies. In this review we will provide an overview of the clinical, radiologic, pathologic, and genetic characteristics of these tumors.

Abdominal small round cell tumor with osteoid and EWS/FLI1

In this report, we described a case of multiple intraperitoneal tumors. Histologically, the tumors were composed of small round cells with malignant phenotype, necrotic areas, and islands of osteoid matrix in the stroma. In immunohistochemical and molecular analyses, the tumors expressed CD99 and EWS-Fli1 fusion gene. Production of osteoid by small round tumor cells was consistent with the histologic criteria of small-cell osteosarcoma, whereas expression of EWS-Fli1 was a characteristic genetic feature of Ewing's sarcoma family of tumor. Such tumors have been limited to a case in which histologically proven small-cell osteosarcoma of the scapula showed a chromosomal translocation, t(11;22)(q24;q12).

Extraskeletal osteosarcoma: an unusual presentation as tarsal tunnel syndrome

Tarsal tunnel syndrome is a compressive neuropathy caused by intrinsic or extrinsic pressure on the posterior tibial nerve or one of its terminal branches. A mass in association with tarsal tunnel syndrome is most likely a benign tumor or tumor-like condition, although a more malignant tumor must be in the differential diagnosis. We report an unusual case of an extraskeletal osteosarcoma causing tarsal tunnel syndrome.