Occult pleural dissemination detected intraoperatively in patients with thymic tumors: a retrospective analysis

Background Thymic tumors usually present with adjacent organ invasion or pleural dissemination, but very few studies have reported on occult pleural dissemination detected intraoperatively. This study aimed to investigate the risk factors that can predict pleural dissemination preoperatively. Methods Consecutive patients with thymic tumors who underwent surgery from January 2010 to January 2017 were reviewed. Only patients without pleural dissemination detected preoperatively were included in this study. Demographic, clinical, pathological, and survival data were collected for statistical analysis. Further analyses were performed to find the risk factors of occult pleural dissemination. Results A total of 352 patients with thymic tumors were included in this study. Seven patients had pleural dissemination detected intraoperatively. All pleural dissemination cases were in clinical Masaoka-Koga stage III, and most underwent the video-assisted thoracoscopic surgery (VATS) approach (or VATS exploration). Univariate analysis showed that positive squamous cell carcinoma (SCC) antigen was the only predictor of pleural dissemination (p = 0.009). Tiny nodules close to the diaphragm were detected in the computed tomography scans of 1 case after reviewing the imaging data. Tumor recurrence occurred in 5 patients during follow-up. The disease-free survival rates were better in patients with a solitary nodule than those with multiple nodules (p = 0.019). No significant difference was detected in terms of disease-free survival rates between SCC antigen positive and SCC antigen negative patients. Conclusions Positive SCC antigen was the only detected risk factor for predicting pleural dissemination in thymic tumors preoperatively in this study. The VATS approach (including VATS exploration) is suggested for patients with clinical Masaoka-Koga stage III and SCC antigen positive thymic tumors, according to our experience.

Bazex Syndrome in Lung Squamous Cell Carcinoma: High Expression of Epidermal Growth Factor Receptor in Lesional Keratinocytes with Th2 Immune Shift

An 82-year-old Japanese man was referred for detailed examination of hyperkeratotic erythematous plaques on his palms and soles for 6 months. Two weeks before his first visit, he had undergone lung lobectomy for right lung squamous cell carcinoma (SCC). Laboratory findings showed elevations of eosinophil counts, serum IgE, thymus and activation-regulated chemokine, SCC antigen, and soluble interleukin-2 receptor levels. Histological results of a skin biopsy involving the left palm showed psoriasiform dermatitis. Before lung lobectomy, the hyperkeratotic erythematous plaques on the palms and soles and the erythemas on the trunk and extremities were difficult to treat with topical steroids. After lobectomy, the skin symptoms dramatically and rapidly subsided with topical steroids. Therefore, we diagnosed Bazex syndrome (BS), also known as acrokeratosis paraneoplastica, as a paraneoplastic cutaneous disease in lung SCC. The mild eosinophilia subsided and levels of SCC antigen, IgE, and soluble interleukin-2 receptor were reduced. BS is a paraneoplastic cutaneous disease characterized by acral psoriasiform lesions associated with an underlying neoplasm. In a previous report, a shift to the Th2 immune condition was found in patients with non-small cell lung cancer, as shown in our patient. Epidermal growth factor receptor (EGFR) is also known as tumor growth factor-α receptor; it is increased in psoriatic keratinocytes. In our case, EGFR expression increased in lesional keratinocytes 2 weeks after surgery and decreased 4 weeks after surgery. We speculate that a shift to Th2 immune reactions in lung SCC may be the pathogenesis of BS, whereby lesional keratinocytes highly express EGFR in parallel with disease activity.