case_images: PMC4104538_01
case_images: Positron emission tomography-computed tomography chest image demonstrates a localized mass in right posterior mediastinal/ paraspinal region with maximum standardized uptake value of 6.6
case_images: CJ-11-16-g001.jpg
case_images: PMC4104538_01_CJ-11-16-g001.jpg
case_images: F1
case_images: No pleural effusion was detected [Figure 1].
case_images: Field's stained smear shows cohesive group of cells on a myxoid background (MGG, x2.5). This smear pattern correlates with groups of tumor cells surrounded by fibrous septa on histology. High power view of vacuolated cells somewhat resembling physalipherous cells, but differentiated from them by pleomorphic large nuclei and prominent nucleoli (inset)
case_images: CJ-11-16-g002.jpg
case_images: PMC4104538_01_CJ-11-16-g002.jpg
case_images: F2
case_images: The smears showed a hypercellular specimen consisting of loosely cohesive "lobules" of heavily vacuolated epithelioid cells displayed against a background of myxoid material, which was highlighted on Field's and Giemsa stained direct smears, suggesting the possibility of chordoma [Figure 2].
case_images: Loosely cohesive epithelioid cells with eccentric nuclei, prominent nucleoli, and ample cytoplasm resembling adenocarcinoma. Note the cell showing vacuolated cytoplasm with magenta droplet (arrow) (myxoid background, x63). Mucicarmine stains were negative to faintly positive
case_images: CJ-11-16-g003.jpg
case_images: PMC4104538_01_CJ-11-16-g003.jpg
case_images: F3
case_images: The vacuoles in the cells were filled with the same myxoid material seen in the background [Figure 3] and were negative for mucicarmine stain. Mitotic activity was easily identified [Figure 3].
case_images: Clusters of epithelioid cells with abundant, poorly defined cytoplasm, mildly pleomorphic nuclei with irregular nuclear membranes (grooves and notches), prominent eosinophilic nucleoli, and chromatin condensation. Rare signet-ring like cells are seen. The myxoid stroma is less obvious in the Papanicolaou (Pap)-stained smear (Pap, x63)
case_images: CJ-11-16-g004.jpg
case_images: PMC4104538_01_CJ-11-16-g004.jpg
case_images: F4
case_images: Occasional cells with intracytoplasmic vacuoles displacing their nuclei to the periphery resembling signet-ring cells were also seen within the lobules, expanding the differential diagnosis to include the possibility of adenocarcinoma [Figure 4].
case_images: Immunohistochemical results. Tumor cells are positive for calretinin, WT-1, and D2-40, and negative for high molecular weight keratin and thyroid transcription factor-1 supporting mesothelial origin. Mucicarmine stain is negative excluding adenocarcinoma
case_images: CJ-11-16-g005.jpg
case_images: PMC4104538_01_CJ-11-16-g005.jpg
case_images: F5
case_images: Negative stains included thyroid transcription factor-1, Ber-EP4, carcinoembryonic antigen, S100 protein, CK20, and CDX-2, which excluded adenocarcinoma and chordoma and further supported the diagnosis of mesothelioma [Figure 5].