Abstract
Lung cancer closely resembling Extraskeletal Myxoid Chondrosarcoma (EMC), called “primary pulmonary myxoid sarcoma (PPMS),” is an extremely rare tumor. This report is presented here of a unique case showing EMC-like changes only in metastases from conventional lung adenocarcinoma in an 81-year-old man. After lung tumor resection and chemo-radiotherapy, he underwent the resection of right adrenal metastasis composed of carcinomatous and EMC-like components. There were multifocal transitions between these components. He was treated with additional chemo-radiotherapy for newly developed liver and brain metastases, but he died 3.3 years after the initial surgery. Autopsy revealed EMC-like tumors, with or without minute adenocarcinomatous components, extensively involving widespread organs. Reverse transcription-polymerase chain reaction did not detect EWSR1- CREB1 fusion in the primary tumor or metastases. These features indicated that the current tumor was different from PPMS characterized by EWSR1-CREB1 fusion. We concluded that such EMC-like features represent morphological changes of metastatic lung adenocarcinoma. We believe that this possible occurrence should be recognized for accurate diagnosis of metastatic lung carcinoma.
Highlights
Extraskeletal Myxoid Chondrosarcoma (EMC) is an uncommon soft-tissue tumor usually originating in the deep tissues [1]
We encountered a unique autopsy case of lung carcinoma showing EMC-like features only in metastases after chemo-radiotherapy
Minute concomitant adenocarcinomatous features were found focally in these myxoid tumors. Adenocarcinomatous components in both the primary tumor and metastases were diffusely positive for pan-cytokeratin, CK7 (Figure 1d), epithelial membrane antigen (EMA), focally positive for carcinoembryonic antigen (CEA), Napsin A, and vimentin, but were negative for CK20, thyroid transcription factor-1 (TTF-1), S-100 protein, CD34, desmin, smooth muscle actin (SMA), or HMB45
Summary
Extraskeletal Myxoid Chondrosarcoma (EMC) is an uncommon soft-tissue tumor usually originating in the deep tissues [1]. Primary lung cancers resembling EMC have been rarely reported as “primary pulmonary myxoid sarcoma (PPMS)” [2,3]. We encountered a unique autopsy case of lung carcinoma showing EMC-like features only in metastases after chemo-radiotherapy. To our knowledge, such EMC-like changes have not been mentioned previously in metastases of lung carcinoma, therapy-induced myxomatous or colloid-like changes have been reported in some other site cancers [4,5].
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