Thymic carcinoma: current and future therapeutic interventions

Thymic Carcinoma: A Review

The diagnosis of thymic carcinoma may pose significant problems not necessarily in the histopathological diagnosis but rather in assigning the thymus as specific origin. Often the tissue available for interpretation is obtained via a mediastinocopic biopsy, which raises two different issues -minimal tissue and lack of specific features to make a carcinoma of thymic origin. In addition, if to that conundrum we add that there is no magic immunohistochemical stain that will unequivocally lead to the interpretation of thymic carcinoma, then we are left with a true clinical-radiological-pathological correlation. In this review, we will highlight some of those challenges that diagnostic surgical pathologists may encounter in the histopathological assessment of thymic carcinoma as well as in the staging of these tumors.

Fluorescence Imaging-Guided Identification of Thymic Masses Using Low-Dose Indocyanine Green

BACKGROUND

Indocyanine green (ICG) fluorescence imaging has been used to detect many types of tumors during surgery; however, there are few studies on thymic masses and the dose and time of ICG injection have not been optimized.

OBJECTIVE

We aimed to evaluate the optimal ICG injection dose and timing for detecting thymic masses during surgery.

METHOD

Forty-nine consecutive patients diagnosed with thymic masses on preoperative computed tomography (CT) and scheduled to undergo thymic cystectomy or thymectomy were included. Patients were administered 1, 2, or 5 mg/kg of ICG at different times. Thymic masses were observed during and after surgery using a near-infrared fluorescence imaging system, and the fluorescence signal tumor-to-normal ratio (TNR) was analyzed.

RESULTS

Among the 49 patients, 14 patients with thymic cysts showed negative fluorescence signals, 33 patients with thymoma or thymic carcinoma showed positive fluorescence signals, and 2 patients showed insufficient fluorescence signals. The diagnosis of thymic masses based on CT was correct in 32 (65%) of 49 cases; however, the differential diagnosis of thymic masses based on NIR signals was correct in 47 of 49 cases (96%), including 14 cases of thymic cysts (100%) and 33 cases of thymomas or thymic carcinomas (94%). In addition, TNR was not affected by the time or dose of ICG injection, histological type, stage, or tumor size.

CONCLUSIONS

Low-dose intravenous injection of ICG at flexible time can detect thymic tumors. In addition, thymic cysts can be distinguished from thymomas or thymic carcinomas during surgery by the absence of ICG fluorescence signals.

Thymic carcinoma metastasize to the small intestine: a case report

BACKGROUND

Thymic carcinoma is a rare mediastinal neoplasm with a high malignant potential. It often shows pleural invasion and distant metastasis. The metastasis of thymic carcinoma to the small intestine is rarely reported and difficult to distinguish from other gastrointestinal tract tumors.

CASE PRESENTATION

An elderly man presented with lower abdominal pain for 2 months. Abdominal CT showed a mass communicated with the small intestinal lumen. After radical resection of the small intestinal tumor, resected specimens showed moderately differentiated squamous-cell carcinoma with lymph nodes metastases. The patient received chest CT and was found to have a mass in anterior mediastinum. Biopsies of the mass revealed thymic squamous-cell carcinoma.

CONCLUSIONS

We highlighted the metastasis of thymic carcinoma to the small intestine is rare and easily misdiagnosed. In patients with a mass communicated with the small intestinal lumen, a suspicion of thymic carcinoma metastasis should not be overlooked and we should make accurate differential diagnosis from the other small intestinal tumors.

Expression of excision repair cross-complementation group 1 and class III β-tubulin in thymic carcinoma

Thymic carcinoma is a rare mediastinum malignant tumor derived from thymic epithelial cells. With the exception of complete resection, an effective therapy has not been established to date for advanced or relapsed thymic carcinoma. The present study examined the protein expression of excision repair cross-complementation group 1 (ERCC1) and class III β-tubulin (TUBB3), which are consider to be indicators of the anticancer activity of platinum-based and taxane-based chemotherapy, respectively. The expression of ERCC1 and TUBB3 proteins was examined in 40 thymic carcinoma patients who underwent either surgical resection or core-needle biopsy. The present study investigated whether the expression of ERCC1 and TUBB3 proteins was associated with the overall survival and clinicopathological factors of thymic carcinoma patients. The expression of ERCC1 and TUBB3 proteins was also evaluated in 50 patients who underwent curative resection for non-small cell lung cancer (NSCLC). The expression of ERCC1 and TUBB3 proteins was positive in 8 cases (20%) among the thymic carcinoma patients. ERCC1 was expressed in 21 cases (42%), while TUBB3 was expressed in 27 cases (54%), among the 50 NSCLC patients evaluated in the present study. Only complete resection was observed to be associated with a better prognosis than incomplete resection (P=0.0341). Other clinicopathological factors, including expression of ERCC1 and TUBB3 proteins, exhibited no effect on overall survival. The expression of ERCC1 and TUBB3 proteins in the thymic carcinoma cases was lower than that in the NSCLC cases. The present results suggest a possibility for better antitumor effects of platinum-based and taxane-based chemotherapy on thymic carcinoma patients.

nab-Paclitaxel in Combination with Carboplatin for a Previously Treated Thymic Carcinoma

We present the case of a 40-year-old man with previously treated thymic carcinoma, complaining of gradually worsening back pain. Computed tomography scans of the chest showed multiple pleural disseminated nodules with a pleural effusion in the right thorax. The patient was treated with carboplatin on day 1 plus nab-paclitaxel on day 1 and 8 in cycles repeated every 4 weeks. Objective tumor shrinkage was observed after 4 cycles of this regimen. In addition, the elevated serum cytokeratin 19 fragment level decreased, and the patient's back pain was relieved without any analgesics. Although he experienced grade 4 neutropenia and granulocyte colony-stimulating factor (G-CSF) injection, the severity of thrombocytopenia and nonhematological toxicities such as reversible neuropathy did not exceed grade 1 during the treatment. To our knowledge, this is the first report to demonstrate the efficacy of combination chemotherapy consisting of carboplatin and nab-paclitaxel against thymic carcinoma. This case report suggests that nab-paclitaxel in combination with carboplatin can be a favorable chemotherapy regimen for advanced thymic carcinoma.