Medullary Thyroid Carcinoma and Papillary Thyroid Carcinoma in the Same Patient as a Collision Tumour

Case reports of collision and composite carcinomas of the thyroid: an insight into their origin and clinical significance

BACKGROUND

Collision and composite carcinomas of the thyroid are extremely rare, and their clinical and biological characteristics are poorly understood.

CASE PRESENTATION

The first case was a 41-year-old female patient with a right thyroid nodule. Pathological diagnosis was papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma composite carcinoma. Surgical treatment was right thyroid lobectomy + left partial thyroidectomy + right central neck lymph node dissection. The second case was a 60-year-old female with bilateral thyroid nodules. Total thyroidectomy was performed, and the pathological diagnosis was thyroid collision carcinoma involving follicular thyroid carcinoma on the left side and PTC on the right side. The clinical, histological and gene changes of collision and composite carcinomas of the thyroid are poorly described. With different biological invasion characteristics, the ideal treatment and the prognosis is currently unknown and individualized treatment is necessary.

CONCLUSIONS

It is recommended that in composite carcinoma, each cancer is evaluated and treated according to the most severe tumor. Collision carcinoma should be treated as two separate synchronous primary tumors. For both collision and composite carcinomas of the thyroid, the follow-up after treatment should be extensive.

Synchronous Hürthle cell and medullary thyroid carcinomas

Hürthle cell carcinoma (HCC) and medullary thyroid carcinomas (MTC) are uncommon histological subtypes of thyroid cancers, each accounting for around 3% of all thyroid cancers. A septuagenarian woman with a history of multiple primary cancer diagnoses presented with a growing left-sided neck lump. A diagnostic left thyroid lobectomy was performed, and pathological examination found two separate malignant foci: one HCC and an MTC. The patient developed left-sided HCC nodal metastasis, and following several multidisciplinary team discussions, a right completion lobectomy with left lateral neck dissection was performed, revealing further intrathyroidal MTC and extranodal extension of HCC. We present this as the first reported case of a collision tumour of HCC and MTC, and review the available literature regarding collision tumours and their management.

Collision tumors of the thyroid. A special clinical and pathological entity

Thyroid collision tumors are rare entities that designate two histologically and morphologically distinct tumors that occur simultaneously or as metastases from other organs within the thyroid. Medullary and papillary carcinoma co-occurrence is the most frequent. Several theories tried to explain the pathogenic mechanisms underlining collision tumors, including the theory which assumes that one tumor predisposes the other, stem cell theory, and random effect theory, but their combination better explains the origin of these tumors. Hypotheses about common genetic behavior responsible for the pathogenesis have also been suggested, such as the involvement of germline mutation of RET (Rearranged during Transfection) proto-oncogene in medullary thyroid carcinoma and papillary thyroid carcinoma coexistence, but there is controversy on this topic. Management of thyroid collision tumors is challenging owing to the presence of two distinct tumors with different biological aggressiveness, treatments options, and prognosis, and needs to be individualized.

Significance of chromogranin A and synaptophysin in medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare thyroid carcinoma of C-cell deviation that produces and secretes calcitonin (CT) and chromogranin A (CgA) into the blood. Thus, CT and CgA are immunohistochemical and serum markers for MTCs. MTC occurs in sporadic and inheritable forms. The hallmark of inheritable cases in multiple endocrine neoplasm 2 (MEN2) is MTC. MEN2 cases represent 30% through germline RET proto-oncogene mutation and occur in younger ages involving bilateral thyroid lobes. Sporadic cases are 70% and occur in older ages. CgA and synaptophysin (SPY) are the two most widely used and reliable immunohistochemical markers for neuroendocrine tumors, including MTCs. This study aimed to detect different immunohistochemical staining patterns for CgA and SPY between non-symptomatic small lesions and invading larger aggressive tumors in both MEA2 cases and sporadic cases. There was different CgA and SPY immunostaining in MEA2 cases where small tumors (≤0.3 cm) were lesser immunostained for CgA and SPY, despite intense staining for CT, compared to the larger (≥0.5 cm) tumors, stronger immunostained for CgA. There was also different CgA and SPY immunohistochemical staining in sporadic cases between small lesions (≤0.5 cm) and larger tumors (≥1.0 cm). One small sporadic tumor (0.5 cm × 0.3 cm) was strongly and weakly, patchy stained for CgA and SPY, respectively, while larger sporadic tumors were diffusely and strongly stained for CgA and SPY. Therefore, stronger CgA and SPY immunostaining for larger tumors in both MEA2 and sporadic cases may be used as independent, aggressive immunohistochemical markers for MTCs.

A case report of simultaneous medullary and papillary carcinoma of thyroid

Objective. Medullary (MTC) and papillary (PTC) thyroid carcinoma are two different types of thyroid carcinoma with significant differences in origin. Their co-occurrence in a patient is a rare phenomenon. We report a patient with simultaneous presentation of both MTC and PTC. Case presentation. A 62-year-old euthyroid woman with a cervical mass was evaluated, underwent total thyroidectomy, and neck dissection. The examination revealed a MTC large nodule as well as a small nodule of the tall cell variant of PTC, along with the concomitant cervical lymph node metastases. Subsequently, the genetic analysis showed BRAF mutations. Adjuvant treatments including radioiodine and thyroid hormone replacement therapies were performed for the patient. Conclusions. The cooccurrence of MTC and PTC in the same patient is a rare phenomenon. The clinical manifestations and biological behavior of these cancers are completely different. Since the therapeutic strategy and prognosis are very different in these patients, accurate diagnosis of this coexistence is very important.

Medullary thyroid carcinoma combined with papillary thyroid carcinoma: case report and literature review

We investigated the clinicopathologic features, immunophenotype, (differential) diagnosis, pathogenesis, treatment, and follow-up of medullary thyroid carcinoma (MTC) combined with papillary thyroid carcinoma (PTC). A retrospective analysis of the clinical and pathologic features and immunophenotype was conducted in a patient with MTC and PTC. Relevant literature was also reviewed. Results of thyroid fine needle aspiration indicated malignant tumor in the right lobe of the thyroid, suggesting PTC; further analysis by biopsy confirmed this diagnosis. The left lobe exhibited MTC. Tumor metastases were absent from the lymph nodes of the left central area (0/2), and no tumor was present in the thymic tissue. In the right lobe and isthmus, PTC was observed, with a maximum infiltration diameter of 0.8 cm, and tumor metastases were absent from lymph nodes of the right central area (0/3). Immunohistochemistry of the left lobe was positive for calcitonin, CK, TTF-1, CD56, CgA, and Congo red, but negative for CK19, thyroglobulin, galectin-3, MC, and CEA, with a Ki-67 proliferation index of 1%. The right lobe was positive for CK19, galectin-3, and MC, but negative for CD56. The V600E mutation was detected in BRAF. MTC combined with PTC is a rare thyroid tumor. This condition is diagnosed mainly based on morphology, immunophenotyping, and molecular detection. It must be distinguished from other malignancies, such as thyroid follicular tumors, undifferentiated carcinoma, poorly differentiated carcinoma, transparent stellate tumor, and mixed PTC/MTC. Surgery and post-operative drug administration currently constitute the preferred treatments.