title: Primary pulmonary and mediastinal synovial sarcoma: a clinicopathologic study of 60 cases and comparison with five prior series.
abstract: Primary pulmonary and mediastinal synovial sarcoma is rare and poses a diagnostic challenge particularly when unusual histological features are present. We present 60 cases of primary pulmonary and mediastinal synovial sarcoma (29 male and 27 female subjects; mean age, 42 years) and compare our results with five prior series to better define unusual histological features. Clinically, patients with mediastinal synovial sarcoma were younger with a male gender bias. Radiologically, tumors were well delineated with distinctive magnetic resonance imaging features and little vascular enhancement. In all, 21/46 patients died of disease within 5 years. Histologically, all tumors had dense cellularity, interlacing fascicles, hyalinized stroma, and mast cell influx. Hemangiopericytoma-like vasculature (48/60), focal myxoid change (30/60), and entrapped pneumocytes (23/60) were seen. Calcification was not prevalent (10/60). Unusual histological features included Verocay body-like formations (7/60), vague rosettes (6/60), well-formed papillary structures (3/60), adenomatoid change (3/60), and rhabdoid morphology (2/60). Immunohistochemistry demonstrated expression of pancytokeratin (39/58), epithelial membrane antigen (29/53), cytokeratin 7 (26/40), cytokeratin 5/6 (5/7), calretinin (15/23), CD99 (19/23), bcl-2 (24/24), CD56 (11/11), S-100 (9/51), and smooth muscle actin (8/32). In total, 92% (36/39) of primary pulmonary and mediastinal synovial sarcomas studied were positive for t(x;18). In conclusion, our study confirms the clinical, histological, immunohistochemical, and molecular data from previous large series of primary pulmonary and mediastinal synovial sarcoma. Compared with soft tissue synovial sarcoma, primary pulmonary and mediastinal synovial sarcoma has less calcification, less obvious mast cell influx, and less radiologic vascularity, but similar magnetic resonance imaging features, percentage of poorly differentiated tumors, and number of t(x;18)-positive tumors. Awareness of focal unusual histology can prevent misdiagnosis particularly in t(x;18)-negative tumors.
authors.affiliation: Department of Pulmonary and Mediastinal Pathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000, USA.
authors.forename: Paul H
authors.initials: PH
authors.lastname: Hartel
authors.forename: Julie C
authors.initials: JC
authors.lastname: Fanburg-Smith
authors.forename: Aletta A
authors.initials: AA
authors.lastname: Frazier
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Galvin
authors.forename: Jack H
authors.initials: JH
authors.lastname: Lichy
authors.forename: Konstantin
authors.initials: K
authors.lastname: Shilo
authors.forename: Teri J
authors.initials: TJ
authors.lastname: Franks
mesh_terms: D000071443:12E7 Antigen; D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D019002:CD56 Antigen / Q000032:analysis; D064032:Calbindin 2; D015815:Cell Adhesion Molecules / Q000032:analysis; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics; D041321:Chromosomes, Human, X / Q000235:genetics; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000032:analysis; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008479:Mediastinal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D064030:S100 Calcium Binding Protein G / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D013584:Sarcoma, Synovial / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015996:Survival Rate; D014178:Translocation, Genetic
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; C576764:CALB2 protein, human; D019002:CD56 Antigen; C061828:CD99 protein, human; D064032:Calbindin 2; D015815:Cell Adhesion Molecules; D015514:Oncogene Proteins, Fusion; D019253:Proto-Oncogene Proteins c-bcl-2; D064030:S100 Calcium Binding Protein G; D009418:S100 Proteins; C116512:SYT-SSX fusion protein; D007633:Keratins