Extraskeletal Osteosarcoma of the Pleura:Report of a Case

Malignant pleural mesothelioma with heterologous elements

AIMS

Malignant pleural mesothelioma with heterologous elements (such as osseous, cartilaginous or rhabdomyoblastic differentiation) is very rare. We tried to differentiate such mesothelioma cases from extraskeletal pleural osteosarcoma, which is very challenging.

METHODS

We compared 10 malignant pleural mesotheliomas (three biphasic and seven sarcomatoid types) with two pleural osteosarcomas using clinicopathological and immunohistochemical methods, and also fluorescence in situ hybridisation (FISH) to examine for homozygous deletion of p16.

RESULTS

The median age was 72 years for mesotheliomas, and 69 years for osteosarcoma. For mesothelioma, eight cases were male and two were female. Growth was diffuse in all mesothelioma cases except case 10, where it was localised, as it was for the two osteosarcomas. Among mesothelioma cases, 80% displayed osteosarcomatous and 60% chondromatous elements, while 10% exhibited rhabdomyoblastic ones. Immunohistochemical labelling for calretinin and AE1/AE3 was present in 8/10 and 7/10 mesotheliomas, respectively, but in only one osteosarcoma. Loss of methylthioadenosine phosphorylase was seen in 5/7 mesotheliomas. FISH analysis revealed homozygous deletion of p16 in 5/8 mesothelioma and 2/2 osteosarcoma. Median survival was 6.5 months after biopsy or surgical operation in mesothelioma, and 12 months after operation in osteosarcoma.

CONCLUSIONS

Although median survival was longer for osteosarcoma than for malignant mesothelioma, we could not differentiate mesothelioma from pleural osteosarcoma on the combined basis of clinicopathological and immunohistochemical data, and FISH analysis. However, diffuse growth was more frequent in mesothelioma than in osteosarcoma.

Primary thoracic extraskeletal osteosarcoma: a case report and literature review

Primary extraskeletal osteosarcoma (ESOS) presenting in thoracic locations is very rare and associated with a poor prognosis. The current study presents a case involving a large anterior mediastinal mass, which was histologically confirmed as a primary osteosarcoma. The literature concerning primary thoracic ESOS is reviewed. A total of 60 cases were identified. The median age was 60 years (range, 14-93 years) and males were more prevalent among the reported cases (65%). Survival analysis revealed that the overall 5-year survival was only 22.3%. The majority of cases of thoracic ESOS presented in the lung (n=24, 40%), with others presenting in the mediastinum, pleura, or chest wall. The benefit of surgery, chemotherapy and radiotherapy was confirmed by Cox regression survival analyses.

Primary extraskeletal pleural osteosarcoma: a rare pleural identity

A 69-year-old female with a history of a heart transplant 16 years prior, presented with a large left chest mass identified on fluoroscopy in the cardiac catheterization lab. The patient noted a 40 pound weight loss in one year. A chest X-ray (CXR) and chest computed tomography (CT) demonstrated a large complex cystic mass in the left chest. A CT guided aspiration was performed, and the cytology for the cyst fluid was negative for malignancy. The patient continued to have worsening shortness of breath, a repeat chest CT scan and magnetic resonance imaging (MRI) three months later, demonstrated a recurrence of the left pleural mass. Further, work-up was negative for tumor. A left video assisted thoracotomy exploration was performed and left thoracotomy was needed for the mass resection. The final pathology demonstrated a high grade osteosarcoma. The post-operative course was unremarkable.

Extraskeletal osteosarcoma arising from the pleura

A 37-year-old woman was referred to our institution for further management of a mass lesion located in the thoracic cavity. The mass had grown by more than 10 cm over the course of a year and was initially considered to be a scar from previous pulmonary tuberculosis at another hospital. The patient had complained of left-sided flank pain for a year and experienced dyspnea for one month. Chest radiography and chest computed tomography revealed an irregular-shaped mass in the left mid to lower pleural cavity. The mass was widely excised through left thoracotomy. Pathologic examination of the biopsy specimen revealed a malignant spindle cell tumor, which consisted of components of osteosarcoma, pleomorphic sarcoma, and leiomyosarcoma. The patient underwent adjuvant chemotherapy and has been doing well without any evidence of recurrence for 14 months.