We describe herein histologic, immunohistochemical, and molecular findings and clinical manifestations of a rare case of an extremely well differentiated papillary thyroid carcinoma (EWD-PTC). Similarly, it is also difficult to diagnose follicular variant papillary thyroid carcinoma (FVPTC), whose diagnosis is still met with controversy. A recently reported entity of well-differentiated tumor of uncertain malignant potential (WDT-UMP) is added to the diagnostic spectrum harboring EWD-PTC and FVPTC. We report this case, because EWD-PTC is different from FVPTC in its papillary architecture, and also from WDT-UMP in its recurrence and metastatic pattern. These morphologically deceptive entities harbored diagnostic difficulties in the past because the diagnosis depended solely on histology. However, they are now diagnosed with more certainty by virtue of immunohistochemical and molecular studies. We experienced a case of EWD-PTC, which had been diagnosed as adenomatous hyperplasia 20 years ago and manifested recurrence with lymph node (LN) metastasis 7 years later. After another 7 years of follow-up, a new thyroid lesion had developed, diagnosed as FVPTC, with LN metastasis of EWD-PTC. One year later, the patient developed metastatic FVPTC in the skull. Immunohistochemically, the EWD-PTC was focally positive for CK19, negative for galectin-3, and focally negative for CD56. Molecular studies revealed BRAF-positivity and K-RAS negativity. The FVPTC in the left thyroid showed both BRAF and K-RAS negativity. In conclusion, EWD-PTC and FVPTC share similar histologic features, but they are different tumors with different molecular biologic and clinical manifestations. A large cohort of EWD-PTC should be included in further study.
Adenocarcinoma, Follicular/pathology/secondary ; Adult ; Carcinoma, Papillary, Follicular/pathology/*secondary ; Female ; Galectin 3/analysis ; Humans ; Hyperplasia/pathology ; Lymphatic Metastasis ; Male ; Middle Aged ; Neoplasm Recurrence, Local/pathology ; Skull Neoplasms/*secondary ; Thyroid Neoplasms/*pathology

Adenocarcinoma, Follicular ; radiotherapy ; secondary ; Adolescent ; Adult ; Aged ; Bone Neoplasms ; secondary ; Carcinoma, Papillary ; radiotherapy ; secondary ; Child ; Chromosome Aberrations ; radiation effects ; Dose-Response Relationship, Radiation ; Humans ; Hypoparathyroidism ; etiology ; Iodine Radioisotopes ; administration & dosage ; Lung ; physiopathology ; Lung Neoplasms ; secondary ; Lymphatic Metastasis ; Middle Aged ; Parathyroid Glands ; physiopathology ; Salivary Glands ; physiopathology ; Thyroid Neoplasms ; genetics ; pathology ; radiotherapy

OBJECTIVETo investigate the indications, safety and difficulties of one stage thyroidectomy and bilateral neck lymph node dissection for well-differentiated thyroid carcinoma.

METHODSA retrospective review was carried out in 36 well-differentiated thyroid carcinoma patients so treated from 1990 to 2004. Various incisions including H, L and modified Kocher types were selected according to the location of primary tumor and status of cervical lymph node metastasis. Either total thyroidectomy or sub-total thyroidectomy combined with bilateral neck lymph node dissection according to the principles of modified radical neck lymph node dissection: preserving the internal jugular vein, spinal accessory nerve and sternocleidomastoid muscles.

RESULTSThere was no operative death in this group. Postoperative complications included: 2 wound bleeding, 3 recurrent laryngeal nerve resection due to tumor involvement, 1 recurrent laryngeal nerve injury, 2 unilateral internal branch of superior laryngeal nerve injury, 9 unilateral external branch of superior laryngeal nerve injury, 3 unilateral accessory nerve injury, 5 unilateral sympathetic nerve injury, 2 unilateral phrenic nerve injury, 6 chylus fistula, 13 temporary hypoparathyroidism, 2 permanent hypoparathyroidism. The dissected lymph nodes were found to be positive from 0 to 21 in each patient with a mean of 8.3. Of the 36 patients: 31 had bilateral positive lymph nodes; 3 unilateral positive; 2 bilateral negative lymph nodes. The follow up period ranged from 1 to 13 years, Three patients died of distant metastasis, 1 died of cerebral vascular accident. 7 patients lost in follow-up. Totally, 25 patients are still alive, 3 patients had local relapse and were surgically treated again.

CONCLUSIONThe procedure of one-stage thyroidectomy and bilateral neck lymph node dissection for well-differentiated thyroid carcinoma is safe, as it is mandatory that at least one unilateral internal jugular vein should be preserved; one unilateral recurrent laryngeal nerves and accessory nerves should not be injured. Well-differentiated thyroid carcinoma patients whose bilateral cervical lymph nodes are clinically suspected to be positive (obviously enlarged, hard, purplish grapelike lymph node) or are confirmed pathologically to be positive are indications for one-stage thyroidectomy and bilateral neck lymph node dissection. Total or sub-total thyroidectomy should be undertaken with emphasis that at least one parathyroid with blood supply should be preserved. It is of utmost importance that not only the cancer be completely resected but the function of the organs be preserved.

Adenocarcinoma, Follicular ; secondary ; surgery ; Adult ; Carcinoma, Papillary ; secondary ; surgery ; Female ; Follow-Up Studies ; Humans ; Hypothyroidism ; etiology ; Lymph Nodes ; pathology ; Lymphatic Metastasis ; Male ; Middle Aged ; Neck Dissection ; Neoplasm Recurrence, Local ; Postoperative Complications ; Retrospective Studies ; Survival Rate ; Thyroid Neoplasms ; pathology ; surgery ; Thyroidectomy ; methods