Desmoplastic Adamantinoma-like Thymic Carcinoma: Clinicopathologic, Immunohistochemical, and Molecular Study of 5 Cases

Non-Small Cell Lung Carcinoma With Clear Cell Features and FGFR3::TACC3 Gene Rearrangement : Clinicopathologic and Next Generation Sequencing Study of 7 Cases

Seven cases of primary lung tumors characterized histologically by clear cell morphology and a distinctive FGFR3::TACC3 gene rearrangement are described. The tumors arose in 4 women and 3 men, aged 47 to 81 years (mean=68). They occurred in peripheral locations, predominantly subpleural, and ranged in size from 1.4 to 6.5 cm (mean=4.1 cm). All tumors showed a solid growth pattern with abundant central areas of necrosis and marked nuclear pleomorphism. The tumors demonstrated clear cell histology, with large cohesive tumor cells displaying atypical nuclei and abundant clear cytoplasm. Immunohistochemical stains identified a squamous phenotype in 5 cases and an adenocarcinoma phenotype in 2 cases. One case was a squamous cell carcinoma with focal glandular component, and one of the squamous cell carcinomas showed focal sarcomatoid changes. Next generation sequencing identified FGFR3::TACC3 gene rearrangements in all 7 cases. One case demonstrated a concurrent activating FGFR3 mutation and a second case demonstrated concurrent FGFR3 amplification. Two cases harbored a concurrent KRAS G12D mutation. One case harbored both KRAS and EGFR mutations, and 1 case had a concurrent TP53 mutation. Non-small cell lung carcinoma harboring FGFR3::TACC3 gene rearrangements is extremely rare, and this rearrangement may potentially be enriched in tumors that demonstrate clear cell histology. Identification of FGFR3::TACC3 in patients with lung carcinomas with clear cell features may be of importance as they could potentially be candidates for therapy with tyrosine kinase inhibitors.

Clinicopathologic characteristics of thymic clear cell carcinoma: a case report with literature review

BACKGROUND

Thymic clear cell carcinoma is a rare mediastinal neoplasm, with only 25 reported cases to date. We report a case of a 45-year-old man with thymic clear cell carcinoma. We think imaging and laboratory tests may be helpful for differential diagnosis.

CASE PRESENTATION

A 45-year-old male was admitted to a local hospital for chest distress with cardiopalmus. CT showed a mediastinal mass. Laboratory examination results were all in the normal range. Histologically, the tumor cells had a clear cytoplasm, and immunohistochemically, the tumor cells were positive for epithelial markers. We performed abdominal and pelvic CT and further examined serum levels of thyroxine, parathyroid hormone and AFP postoperatively, which were normal. The patient received postoperative radiotherapy, and CT showed left adrenal metastasis at 20 months after surgery.

CONCLUSION

Thymic clear cell carcinoma is a rare malignant neoplasm. Adrenal metastasis can occur. Patients undergo thymectomy with chemotherapy or with radiotherapy have better outcoming. Metastasis, direct invasion of parathyroid carcinoma and other primary tumors in the mediastinum should be excluded. Immunohistochemical markers, imaging and laboratory examination can help to exclude metastasis.