Calcitonin negative medullary thyroid cancer in ectopic thyroid tissue: a rare diagnosis in an unusual location

Fine-needle aspiration diagnosis of secondary malignant tumors of the thyroid gland: A single-institution experience of 17 cases

BACKGROUND

Fine-needle aspiration (FNA) is the most commonly used preoperative pathological diagnostic tool for thyroid tumors. Secondary malignant tumors of the thyroid gland account for less than 3% of all thyroid malignancies. The aim of this study was to investigate the types and cytopathological features of secondary thyroid tumors, evaluate diagnostic pitfalls in FNA.

METHODS

Cases of secondary thyroid tumors diagnosed in the Department of Pathology of Shaanxi Provincial People's Hospital were collected, and their clinical data, cytologic features, immunohistochemical results, and histopathological diagnoses were summarized.

RESULTS

The study included 17 cases (8 males and 9 females) with a mean age of 60.4 ± 9.4 years (range, 45-83 years). Six cases had a known history of primary malignancy prior to FNA aspiration diagnosis. The most common organs of origin were the lungs (5 cases, 3 adenocarcinoma, and 2 small-cell carcinoma) and esophagus (5 cases, 3 squamous-cell carcinoma, 1 adenocarcinoma, and 1 small-cell carcinoma). The next most common was squamous-cell carcinoma of the larynx (3 cases), and gastric tumor (2 cases), including 1 lymphoma and 1 adenocarcinoma. Cell blocks and immunohistochemistry were performed in 12 of these cases. Comparison of the impact of positive history and IHC availability on the accuracy of pathologic diagnosis showed that both were statistically significant.

CONCLUSION

FNA is an effective means of diagnosing secondary malignancies of the thyroid, in which knowledge of the patient's history of malignancy is essential, and the use of cell blocks and immunohistochemistry helps to clarify the pathological diagnosis.

Advances in targeted therapy and biomarker research in thyroid cancer

Driven by the intricacy of the illness and the need for individualized treatments, targeted therapy and biomarker research in thyroid cancer represent an important frontier in oncology. The variety of genetic changes associated with thyroid cancer demand more investigation to elucidate molecular details. This research is clinically significant since it can be used to develop customized treatment plans. A more focused approach is provided by targeted therapies, which target certain molecular targets such as mutant BRAF or RET proteins. This strategy minimizes collateral harm to healthy tissues and may also reduce adverse effects. Simultaneously, patient categorization based on molecular profiles is made possible by biomarker exploration, which allows for customized therapy regimens and maximizes therapeutic results. The benefits of targeted therapy and biomarker research go beyond their immediate clinical impact to encompass the whole cancer landscape. Comprehending the genetic underpinnings of thyroid cancer facilitates the creation of novel treatments that specifically target aberrant molecules. This advances the treatment of thyroid cancer and advances precision medicine, paving the way for the treatment of other cancers. Taken simply, more study on thyroid cancer is promising for better patient care. The concepts discovered during this investigation have the potential to completely transform the way that care is provided, bringing in a new era of personalized, precision medicine. This paradigm shift could improve the prognosis and quality of life for individuals with thyroid cancer and act as an inspiration for advances in other cancer types.

Serum Calcitonin-Negative Medullary Thyroid Carcinoma: A Case Series of 19 Patients in a Single Center

INTRODUCTION

Medullary thyroid carcinoma (MTC) is a rare cancer that accounts for 5% of thyroid cancers. Serum calcitonin is a good biomarker for MTC, which is used for diagnosis, prognosis, and monitoring of recurrence. Calcitonin-negative MTC (CNMTC) is rare but confounds diagnostic and prognostic directions. This study introduces 19 cases of CNMTC in a single center.

METHOD

From 2002 March to 2020 July, more than 76,500 patients had undergone thyroid surgery due to thyroid cancer at the Severance Hospital, and a total of 320 patients were diagnosed with MTC (0.4%). Serum calcitonin levels were obtained from every patient who was suspected with MTC. These patients had undergone either bilateral total thyroidectomy or unilateral thyroidectomy with central compartment lymph node dissection, and additional modified radical lymph node dissection if lateral lymph node metastasis was positive. Postoperative monitoring and out-patient clinic follow-up were performed with obtaining the serum calcitonin levels.

RESULT

Nineteen patients tested negative for calcitonin preoperatively (6%). The mean preoperative calcitonin level was 5.1pg/mL if undetectable level is regarded as 0pg/mL. Only two patients were males, and the female bias was significant (p = 0.017). No one except two patients with modified radical neck dissection showed central compartment lymph node metastasis. Every patient's postoperative calcitonin level remained low. The median follow-up period was 71 months. There was no recurrence and only one fatality, and the overall survival rate was 95%.

CONCLUSION

Since incidence of CNMTC is not negligible, MTC should not be ruled out in the diagnostic phase even if serum calcitonin is negative in preoperative examination. We presented 19 cases of CNMTC whose prognosis in general were favorable. Markers of serum and immunohistochemical samples other than calcitonin should be actively examined.