De-differentiation of papillary thyroid carcinoma into squamous cell carcinoma. A case of coexistence within an excised neck lesion

Papillary Thyroid Carcinoma Incidentally Found in Cervical Lymph Nodes During Neck Dissection for Patients With Tongue Squamous Cell Carcinoma: A 3-Case Report and Literature Review

The incidence of papillary thyroid carcinoma (PTC) found in the cervical lymph nodes during neck dissection for patients with tongue squamous cell carcinoma (SCC) is infrequent, with the coexistence of PTC and SCC in the same cervical lymph node being the rarest. Some of these patients present with primary lesions in the thyroid gland, whereas others have no obviously malignant thyroid lesion. The reasons behind this clinical phenomenon and the relationship between tongue SCC and PTC found in the cervical lymph nodes are unclear. Moreover, for surgeons, making the choice between thyroid surgery and follow-up is still a clinical dilemma. Of the 956 patients who underwent neck dissection owing to maxillofacial tumors from January 2011 through December 2017 at Second Xiangya Hospital of Central South University, 3 with tongue SCC presented with PTC in the cervical lymph nodes. Neither the preoperative physical examination nor ultrasonography after surgery showed substantial nodules in the thyroid glands of these patients, so none of them underwent thyroid surgery or chemoradiotherapy. At follow-up (1 to 6.5 years), we found no obviously malignant lesions in the patients' thyroid glands or related metastatic disease. Our study suggests that tongue SCC may not affect the occurrence and development of PTC in the cervical lymph nodes. For patients with tongue SCC presenting with PTC in the cervical lymph nodes, it is not necessary to carry out thyroid surgery immediately if ultrasonography shows no substantially malignant lesion in the thyroid gland. Nevertheless, conducting periodic follow-up is very important.

A rare case of ectopic papillary thyroid carcinoma transformed into squamous cell carcinoma

A rare case of a metastatic ectopic papillary thyroid carcinoma (PTC) of the lung that transformed into a squamous cell carcinoma (SCC) that resembles pulmonary SCC is reported. A subcutaneous ectopic PTC in the left anterior neck area, together with a normal thyroid gland, were excised. The ectopic PTC showed thyroglobulin, TTF-1 and PAX-8 immunoreactivity and a BRAF V600E mutation. During the post-operative follow-up period, a rapidly growing 2 cm nodular lesion in the lower left lobe of the lung was detected. The lung tumor consisted of solid sheets and nests of squamous cells but without the nuclear features of PTC. Neither papillary nor follicular structures of cancer cells were identified. Carcinoma cells were positive for TTF-1, PAX-8, p40, CK14, and p63, while showing a high Ki-67 labeling index and a BRAF V600E mutation. These results support our interpretation of a PTC that originated from ectopic thyroid tissue in the left anterior neck and that developed a lung metastasis showing squamous cell differentiation.

Squamous Cell Carcinoma of the Thyroid as a Result of Anaplastic Transformation from BRAF-Positive Papillary Thyroid Cancer

Papillary thyroid carcinoma (PTC) is the most common malignant neoplasm of the thyroid. Majority of the PTC carries an excellent prognosis. However, patients with tall cell variant (TCV) of papillary thyroid carcinoma have a worse prognosis than those with the classic variant. On the other hand, squamous cell carcinoma of the thyroid (SCT) is an unusual neoplasm thought to arise as a primary tumor or as a component of an anaplastic or undifferentiated carcinoma. We report a patient with TCV of PTC presenting years later with squamous transformation. In addition, the patient was found to have BRAF mutation. Such dedifferentiation is considered to be a rare phenomenon and has been reported only in the form of case reports in the literature. The relationship between BRAFV600E mutation and squamous cell transformation of papillary thyroid cancer is unknown at this time. Meticulous pathology is needed to identify such variants. Our patient responded to treatment with concurrent chemotherapy with carboplatin and paclitaxel along with radiation.

Clinicopathological features of recurrent papillary thyroid cancer

Background

To investigate the clinicopathological features of recurrent papillary thyroid carcinoma (PTC).

Methods

A retrospective analysis on clinical and pathological data of 34 patients with recurrent PTC was carried out. A total of 281 patients with non-recurrent PTC during the same time period were chosen as the control group.

Results

Patients were divided into three groups according to the pathological subtype. The number of patients belonging to Groups 1, 2, and 3 were 28, 154, and 133, respectively. 78 patients underwent partial or whole thyroidectomy, 151 cases underwent thyroidectomy combining neck regional lymph node dissection, and 86 patients underwent thyroidectomy combining modified or radical neck dissection. Univariate analysis showed that PTC recurrence was associated with tumor size, extrathyroid invasion, initial surgery approach, lymph node metastasis, and pathological subtype (P < 0.05). Patient age, gender, complication with Hashimoto's thyroiditis, and multifocality were unrelated to PTC recurrence (P > 0.05). Multivariate analysis showed that initial surgery approach and pathological subtype perform important functions in PTC recurrence (P < 0.001). Initial surgery approach presented a negative correlation with PTC recurrence (β = −0.320, OR = 0.726). The pathological subtype was also related to PTC recurrence (β = 0.923, OR = 2.517).

Conclusion

PTC patients without neck dissection showed greater likelihood of postoperative recurrence. Patients with the tall cell, columnar cell, diffuse sclerosing, and oncocytic variants showed a higher propensity for PTC recurrence after operation compared with those who did not. Tumor volume, extrathyroid invasion, and multiple lymph node metastases at the time of initial operation were also significantly related to postoperative recurrence. Follow-up supervision must be enhanced after initial treatment to mitigate PTC recurrence in susceptible patients. Effective and standard treatments must be adopted immediately after the discovery of recurrence.