Medullary thyroid carcinoma (MTC) is a rare malignancy arising from parafollicular C cells of the thyroid gland, sometimes due to germline mutations in the RET protooncogene. Testicular cancer is the most common malignancy in men aged 15 - 40 years with survival rates improved by the introduction of cisplatin therapy in the late 1970s. Nonetheless, platinum-based chemotherapy was shown to increase the risk of a solid second cancer with substantially increased site-specific risk of malignancies of thyroid, melanoma, kidney and bladder.
Case report: We present the case of a 42-year-old man diagnosed with MTC during oncological follow-up for testicular seminoma.18FDG PET-CT showed increased uptake in a single thyroid nodule 1 month after completion of chemotherapy (3 cycles of cisplatin, etoposide and bleomycin). The patient had left orchiectomy 8 months before. Thyroid ultrasound revealed an isoechoic nodule on the lower right lobe of 4.7/3.5/3.5 cm and suspicious bilateral lymph nodes. High serum levels of calcitonin (3820 pg/ml), carcinoembryonic antigen (12.2 ng/ml) and fine-needle aspiration citology smears were suggestive of MTC. Screening for other components of multiple endocrine neoplasia 2 syndromes was negative and no germinal mutations in the RET gene were detected either. Total thyroidectomy along with bilateral neck lymph node dissection were performed. Pathology yielded a diagnosis of MTC in the right lobe with metastasis in one ipsilateral lymph node. Immunohistochemistry revealed diffuse staining for Chromogranin A, TTF1 and CEA, weak focal staining for Calcitonin and strong SSTR2 and SSTR5 positive staining. Postoperative follow-up at 6 and 8 weeks revealed high serum calcitonin (338 pg/ml) and cervical ultrasound showed a small tissue remnant in thyroid bed and several suspicious cervical lymph nodes. No other mets were detected on 18FDG PET-CT. Second intervention surgery for neck dissection was performed with several metastatic lymph nodes excision and calcitonin reassessment was scheduled at 6 wks postop follw-up.
Discussion: The relationship between papillary and follicular thyroid cancer along with testicular germ cell tumour has been described as a consequence of cisplatin chemotherapy, however literature review showed no association of MTC and testicular seminoma so far. Screening with Next Generation Sequencing panel for 4813 Genes (TruSightTM) is under consideration.
Conclusion: Association of Ret negative MTC and testicular seminoma diagnosed 8 months apart suggest synchronous association of the two cancers worth of a wider genetic screening with NGS.
21 May 2022 - 24 May 2022