Presentation
Staging workup for a patient with a recent diagnosis of colorectal carcinoma.
Patient Data
Selected images of an FDG-PET CT study demonstrates a region of increased uptake in the left thyroid lobe and also some uptake within some ipsilateral lymph nodes. The remainder of the study (not shown) showed uptake in the rectum/sigmoid (the primary tumor), in perirectal lymph nodes, and some peritoneal implants.
Targeted neck ultrasound confirms a circumscribed predominantly hypoechogenic nodule in the left thyroid lobe which shows some peripheral vascularity. No other thyroid suspicious lesions were seen. Left level III/IV lymph node with no fatty hilum identified. Both lesions were sampled with FNA.
Case Discussion
This patient has been treated with the rectal tumor resection, hyperthermic intraperitoneal chemotherapy (HIPEC), and chemotherapy for the colorectal disease. FNAs of the neck have demonstrated papillary thyroid carcinoma.
Further thyroidectomy and neck dissection has been performed:
MICROSCOPIC DESCRIPTION: 1-3. Sections show unremarkable parathyroid tissue admixed with adipocytes. There are no atypical features. 4. The tumor is a conventional papillary thyroid carcinoma comprising papillae and cords of columnar cells within fibrotic stroma. Tumor cells have crowded, overlapping nuclei with irregular nuclear borders, grooves and chromatin clearing. Lymphovascular invasion is present. Perineural invasion is not seen. Tumor extends into surrounding fat but there is no invasion of skeletal muscle. Tumor is within 0.5 mm of the posterior margin. A 1 mm focus of papillary carcinoma is also seen in the left lobe away from the main tumor focus. The remaining thyroid is unremarkable. A small area of normal parathyroid tissue is seen on the right side. 5. Sections show seven of ten lymph nodes with metastatic papillary carcinoma, 1-7 mm in size. Extranodal extension is not present. 6. Sections show one of sixteen lymph nodes with metastatic papillary carcinoma, 13 mm in size. Extranodal extension is not present. 7. Sections show one of six lymph nodes with metastatic papillary carcinoma, 10 mm in size. Extranodal extension is not present. 8. Sections show six of nine lymph nodes with metastatic papillary carcinoma, 2-13 mm in size. Extranodal extension is not present. 9. Sections show six lymph nodes with no evidence of malignancy.
DIAGNOSIS: Papillary thyroid carcinoma - Arising in left mide lobe - 15 mm maximum dimension - Lymphovascular invasion present - Narrowly clear of margins - No invasion of strap muscles - Separate 1 mm focus within left lobe, clear of margins - 15 of 47 lymph nodes with metastatic carcinoma, 1-13 mm in size, no extranodal spread; (central 7/10, 2A 1/16, 3 1/6, 4 6/9, 5 0/6). Small amount of normal parathyroid tissue.