Follicular carcinoma originating from struma ovarii: A case report.

INTRODUCTION: Follicular carcinoma originating from struma ovarii is a clinically rare low-grade malignant tumor. The pathological diagnosis of ovarian thyroid follicular carcinoma is predominantly based on the infiltrative growth and vascular involvement of tumor cell nests of different sizes in the ovarian parenchyma. PATIENT CONCERNS: Here we present a case of this malignancy in which the bilateral ovaries, right oviduct wall, myometrial surface, omentum, and bladder reflex were extensively involved Microscopically, the thyroid follicles in this case showed infiltrative growth of nodules of different sizes in the ovarian stroma. DIAGNOSIS: The epithelial layer of the follicles was atypical, but with no nuclear features of papillary thyroid carcinoma such as nuclear groove and nuclear pseudoinclusions. Immunohistochemistry showed positive expression of thyroglobulin, thyroid transcription factor-1, and cytokeratin19, with a Ki-67 index of 5% +. Immunohistochemical results combined with microscopic morphology allowed a diagnosis of follicular carcinoma originating from struma ovarii. INTERVENTIONS: After exclusion of contraindications to surgery, the patient underwent surgical exploration on July 26, 2022, during which frozen pathological examination was performed. OUTCOMES: The patient recovered well and was discharged. At the first follow-up visit in October 2022, the patient had an excellent survival. CONCLUSION: The analysis of the microscopic morphological characteristics and immunohistochemistry deepened our understanding of the pathological characteristics of ovarian and thyroid follicular carcinoma, and further provides a diagnostic reference for other clinicians who will encounter these conditions in the future.

Malignant transformation of Warthin's tumor into squamous cell carcinoma: A case report.

Malignant transformation of Warthin's tumor into squamous cell carcinoma is rare. The present study reported on a case of a 67-year-old male patient diagnosed with this condition. Microscopically, the tumor was mainly composed of squamous cell carcinoma and lymphoid stroma. Furthermore, the squamous cell carcinoma cells were arranged in a solid flake-like, papillary and cystic shape. Local bleeding was observed in the mass and a large number of lymphoid stroma-associated centers were observed between the cancer cells. The expression of cytokeratin (CK)5/6, P40, CK7, CK18, CK8 and MutS protein homolog 2 was detected by immunohistochemistry, in addition to Epstein-Barr encoding region in situ hybridization (-), Ki-67 (epithelial 25% +) and p53 (wild-type). The diagnosis of malignant transformation of Warthin's tumor into squamous cell carcinoma depends on the histopathology. The microscopic diagnosis is based on the dynamic process of scaling, atypical hyperplasia and cancerization of the eosinophilic columnar epithelium. Of note, it is also necessary to differentiate it from cervical malignant tumors such as lymphoepithelial carcinoma. The main clinical treatment is surgical resection with negative margins.

Small-cell lung cancer transformation from EGFR-mutant adenocarcinoma after EGFR-TKIs resistance: A case report.

RATIONALE: With the recent advancements in molecular biology research, epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) have emerged as excellent therapies for patients with EGFR-mutant cancers. However, these patients inevitably develop cross-acquired resistance to EGFR-TKIs. Transformation to small-cell lung cancer (SCLC) is considered a rare resistance mechanism against EGFR-TKI therapy. Here, we report a case of TKI resistance due to SCLC transformation and demonstrate its mechanisms and clinical features. PATIENT CONCERNS: A 54-year-old Chinese man with a history of smoking for 40 years complained of an intermittent cough in March 2019. DIAGNOSIS: Transbronchial lung biopsy was performed on the basal segment of the left lower lobe, which confirmed lung adenocarcinoma. In January 2020, repeat biopsy was performed, and the results of immunohistochemistry (IHC) staining showed TTF-1 (+), CK7 (+), napsin A (+), syn (+), and CD56 (+), with a Ki-67 (+) index 80% of small cell carcinomas. Infiltrating adenocarcinomas and small cell carcinomas were observed. INTERVENTIONS: Icotinib (125 mg thrice daily) was administered as a first-line treatment from June 2019. We subsequently administered a chemotherapy regimen consisting of etoposide (180 mg, days 1-3) plus cisplatin (45 mg, days 1-3) every 3 weeks for 1 cycle after recurrence. As the patient could not tolerate further chemotherapy, he continued taking icotinib orally and received whole-brain radiotherapy 10 times to a total dose of 30 Gy after brain metastases. OUTCOMES: The patient relapsed after successful treatment with icotinib for 9 months. A partial response was achieved after 4 cycles of chemotherapy, and despite the brief success of chemotherapy, our patient exhibited brain metastasis and metastases of the eleventh thoracic spine and the second lumbar vertebra with pathological fracture. The patient eventually died of aggressive cancer progression. LESSONS: Our case highlights the possibility of SCLC transformation from EGFR-mutant adenocarcinoma and the importance of repeat biopsy for drug resistance. Serum neuron-specific enolase levels may also be useful for detecting early SCLC transformation.