A Rare Case of Intrapulmonary Ewing Sarcoma Presenting with Left Atrial Tumor Thrombus

Abstract

A previously healthy 24-year-old woman presented with shortness of breath. Chest radiograph (Fig. 1A) showed complete right upper and lower (RUL) lobe collapse with leftward mediastinal shift and abrupt cutoff of the right mainstem bronchus suggestive of an obstructing lesion. Chest computed tomography (CT) (Fig. 1B, C) revealed a 9-cm RUL mass (white arrowheads) with endobronchial invasion and suspected mediastinal involvement (black arrows). Pathology from bronchoscopic cytology (Fig. 2) yielded translocation-positive Ewing sarcoma. Positron emission tomography-CT showed hypermetabolic osseous foci compatible with metastases (Fig. 1D, E) and a hypermetabolic RUL mass extending toward the left atrium (LA) (Fig. 1F, G). An 18-month combination chemotherapy of cyclophosphamide–doxorubicin–vincristine/ifosfamide–etoposide was started to downsize the tumor before a possible surgical resection. To clarify possible tumor invasion into the heart, echocardiography was performed, identifying a 2.8 × 2.2 cm mass (Fig. 1H) entering the LA through the pulmonary vein. The differential diagnosis was thrombus versus invading tumor. For further clarification, cardiovascular magnetic resonance (CMR) imaging was performed, revealing a well-circumscribed heterogeneous RUL mass with areas of necrosis and hemorrhage (Fig. 1I). The mass invaded the right hilum, obstructed the right mainstem bronchus, and grew into the LA through the right superior pulmonary vein (Fig. 1I, black arrow). In addition, comparison between coronal positron emission tomography-CT (Fig. 1F) and CMR (Fig. 1I) revealed additional tissue apposed to the hypermetabolic tumor thrombus. Early postcontrast CMR confirmed the presence of a bland LA thrombus (Fig. 1J, black arrow), adherent to the enhancing tumor thrombus (white arrowhead). On the basis of the findings obtained by CMR, the patient was immediately placed on anticoagulation therapy.FIGURE 2Photomicrographs of the H&E-stained cell-block sample (upper panel, ×40 magnification) and Papanicolaou-stained bronchoscopic cytology sample (bottom panel, ×40 magnification) are shown. The H&E slide demonstrates a “small round blue cell” tumor with dark nuclei and minimal cytoplasm consistent with Ewing sarcoma cells. The Papanicolaou-stained slide shows better morphology and nuclear characteristics with central nucleoli and a rare mitosis. The characteristic cytologic finding in Ewing sarcomas is a dimorphic cell population; one being larger with a more pale nucleus (black arrow, pink/clear vacuoles in the pale cytoplasm) and the second with smaller size and darker nucleus (surrounding the pale cells).3Sanati S Lu DW Schmidt E Perry A Dehner LP Pfeifer JD Cytologic diagnosis of Ewing sarcoma/peripheral neuroectodermal tumor with paired prospective molecular genetic analysis.Cancer. 2007; 111: 192-199Crossref PubMed Scopus (43) Google Scholar H&E, hematoxilyn–eosin.View Large Image Figure ViewerDownload (PPT) The Ewing sarcoma family of tumors has a neural crest cell origin. Most of these tumors exhibit a translocation between chromosomes 11 and 22.1Grier HE The Ewing family of tumors. Ewing's sarcoma and primitive neuroectodermal tumors.Pediatr Clin North Am. 1997; 44: 991-1004Abstract Full Text Full Text PDF PubMed Scopus (259) Google Scholar The majority of tumors typically affect the skeleton. Rare manifestations, however, have been reported in several extraosseal tissues.1Grier HE The Ewing family of tumors. Ewing's sarcoma and primitive neuroectodermal tumors.Pediatr Clin North Am. 1997; 44: 991-1004Abstract Full Text Full Text PDF PubMed Scopus (259) Google Scholar Primary pulmonary Ewing tumor is an extremely rare manifestation of the extraosseus Ewing sarcomas (EES). As of today, the number of primary pulmonary EES cases reported in literature is less than 15, including only one case of primary pulmonary EES invading the heart.2Paul S Ramanathan T Cohen DM et al.Primary Ewing sarcoma invading the heart: resection and reconstruction.J Thorac Cardiovasc Surg. 2007; 133: 1667-1669Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar Our case report highlights the importance of multimodality imaging for the diagnostic assessment of the primary tumor, tumor direct invasion, and metastasis and emphasizes the role of CMR in the differential diagnosis of intracardiac tumor mass and thrombus.