The correlation of histogenesis between metaplastic thymoma and thymic sarcomatoid carcinoma is unclear. We report a case of metaplastic thymoma transformed into high-grade sarcomatoid carcinoma. A 64 × 54 × 32 mm anterior mediastinal mass in a 61-year-old woman microscopically consisted mainly of classic metaplastic thymoma, with the center dominated by high-grade sarcomatoid carcinoma. In some areas, both epithelial and spindle cell components of the metaplastic thymoma showed increased cellular atypia, mitotic activity, and focal necrosis and gradually transformed into the polygonal/pleomorphic and spindle cell components of sarcomatoid carcinoma. Immunohistochemically, the characteristics of the polygonal/pleomorphic sarcomatoid cells were similar to those of the epithelial component of metaplastic thymoma, while the spindle sarcomatoid cells were more similar to the spindle cells component of metaplastic thymoma. The Ki-67 index was less than 5% in the metaplastic thymoma areas but up to 70% in the sarcomatoid carcinoma area. Radical operation and postoperative radiotherapy were performed. Multifocal relapses at the pleura occurred 13 months after surgery.
Pulmonary lymphatic epithelioma-like carcinoma (LELC) is a rare and unique subtype, accounting for 0.9% of all lung cancers. To date, just over 200 cases have been reported worldwide. The Epstein–Barr virus plays a role in the pathogenesis of LELC. Most patients are from East Asia, especially southeastern China. Chest computed tomography mainly shows a single lump or nodule around the lung. In this article, we report a 49-year-old male patient from a non-epidemic area who was hospitalized for “intermittent blood in his phlegm for more than 4 months”. Imaging revealed two nodules in the left lower lobe of his lung. Transbronchial lung biopsy was performed on one of the nodules, and he was diagnosed with primary LELC. Single-photon emission computed tomography revealed that he had hypertrophic pulmonary osteoarthropathy, which is a rare symptom of paraneoplastic syndrome. Because the preoperative evaluation considered early-stage disease, video-assisted thoracoscopic surgery for the left lower lobe and mediastinal lymph node dissection were performed. Both lesions were eventually diagnosed as LELC. Fortunately, lymph node metastasis did not occur, and he did not receive other postoperative treatments. He was followed up for 1 year, and no recurrence was found.
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