Colorectal cancer metastases in thyroid: case report and literature review

BACKGROUND

The thyroid gland is an uncommon site for metastatic deposits from non-thyroid malignancies, occurring in only 1.4 - 3% of surgical specimens where malignancy is suspected. It is even rarer for the source of thyroid metastases to be of colorectal origin. In most cases reported, colorectal metastases in the thyroid occurs many years later after the primary colorectal cancer has been diagnosed and treated. In this unique case, a primary sigmoid carcinoma metastasised to the thyroid gland and presented synchronously as a thyroid nodule.

CASE PRESENTATION

We describe a case of a 64-year-old Caucasian woman who presented with clinical features of metastatic cancer of unknown origin. Her medical history included underlying hyperthyroidism. She had a large pelvic mass adjacent to the sigmoid colon, a left lower lobe lung mass and a suspicious nodule in the left thyroid lobe. A fine-needle aspiration biopsy of the thyroid nodule was performed, which remarkably showed malignant cells originating from primary colorectal cancer on immunohistochemical staining. The patient was managed with palliative chemotherapy given the poor prognosis due to disseminated colorectal malignancy.

CONCLUSIONS

Colorectal adenocarcinoma metastases can rarely present as a metastatic thyroid nodule. Fine-needle aspiration should be performed in suspicious thyroid nodules and may be the least invasive way of identifying a metastatic colorectal or other non-thyroidal malignancy in patients presenting with an unknown primary. The pathologist should be vigilant to this possibility and specific immunohistochemical markers should be used to ensure accurate diagnosis. In thyroid metastases, the prognosis is ultimately determined by the primary tumour but thyroidectomy still has a role in alleviating compressive symptoms and can potentially improve survival in selected cases.

Discordance Between the American Thyroid Association and the American College of Radiology Guideline Systems for Thyroid Nodule Biopsy

BACKGROUND

Previously, fine-needle aspiration biopsy was recommended for any thyroid nodule >1.0 cm in size. In 2015, the American Thyroid Association (ATA) introduced a pattern-based approach for biopsy recommendations based on size and ultrasound (US) characteristics. In 2016, the American College of Radiology (ACR) published the Thyroid Imaging Reporting and Data System, using a point-based system that assesses risk of US characteristics.

METHODS

This study aims to compare recommendations for thyroid nodule biopsy between the ATA and ACR systems and identify outcomes of nodules with discordant recommendations (DRs). US characteristics, fine-needle aspiration biopsy, and surgical pathology results were evaluated for all patients with >1.0 cm thyroid nodules treated at a single tertiary-care institution from 2010 to 2018.

RESULTS

Inclusion criteria were met by 1100 nodules from 687 patients; 42.8% (n = 471) had DR between the ATA and ACR guidelines. All (100%) DR nodules were not recommended for biopsy by ACR, though 53% were recommended to have follow-up. A majority (79%) of DR nodules were recommended for biopsy by ATA, with the remaining 21% recommended for follow-up. Among surgically excised DR nodules (n = 292), 10.3% (n = 30) nodules were found to be malignant, with the vast majority (90.3%) being well-differentiated carcinoma. Among malignant nodules, the ACR would not have recommended biopsy or follow-up for 26.7% (n = 8).

CONCLUSIONS

The ACR classification system is more restrictive compared with the ATA system for recommending thyroid nodule biopsy. This discrepancy could result in confusion for clinicians and delay in diagnosis or therapy for patients with thyroid cancer.

The dangers of parathyroid biopsy

Background

We report an unusual case of a 66-year-old female with a suspicious thoracic outlet mass presenting with severe biochemical hyperparathyroidism and classic hypercalcemic symptoms of renal and bone involvement.

Case Presentation

There was clinical suspicion for parathyroid carcinoma, further supported by intra-operative findings. However, the final pathology described a primary hyperceullar parathyroid lesion with pathognomonic changes secondary to fine-needle aspiration (FNA) biopsy, along with a separate parathyroid lesion likely resulting from seeding along the needle tract. Upon further review, record of a remote FNA was discovered. This case highlights the complications associated with parathyroid FNA resulting in a diagnostic challenge and raising the possibility of malignancy.

Conclusions

We therefore recommend to take caution when there is a prior parathyroid FNA, as it can present with the risks of a secondary lesion from seeding and increase resemblance of malignancy both clinically and through pathologic diagnosis.

Isolated adrenal cryptococcosis, diagnosed by fine-needle aspiration biopsy: a case report

This report documents a case of isolated adrenal gland cryptococcosis without the often reported component of concomitant meningitis or Addison's disease in an immune competent patient. Furthermore, both the patient's lung cancer and adrenal infection with cryptococcus were incidentally discovered during work-up for syncope in the setting of hyponatremia. This case also underscores the diagnostic value of fine-needle aspiration biopsy in this unusual presentation.