High survival simultaneous occurrence of papillary thyroid carcinoma and ectopic thyroid with medullary thyroid carcinoma; case report and literature review

Abstract

Thyroid cancer is usually treated with surgical intervention followed by ablative radiotherapy if indicated to eliminate any metastases. Five-year survival rates are 99% for papillary thyroid carcinoma (PTC) and 82% for medullary thyroid carcinoma (MTC). The chances of survival decrease significantly with two simultaneous types of cancers and with male gender. PTC and MTC present as different entities. The coexistence of different types of thyroid carcinoma in a patient is a rare event. We report the case of a 45-year-old Saudi male with a rare synchronous occurrence of PTC in the thyroid gland, along with ectopic MTC with a unique prognosis over the years. Our case adds data to the literature supporting the coincidental coexistence of PTC and MTC.

Introduction

Originating from follicular thyroid cells, papillary thyroid carcinoma (PTC) is the commonest type of thyroid cancer, accounting for ~85% of all thyroid cancers [1]. Medullary thyroid carcinoma (MTC), arising from parafollicular C-cells, is uncommonly seen in clinical settings. Each type has a completely different embryological origin, suggesting different entities [2]. Established risk factors are age, female gender, and exposure to radiation [3]. The coexistence of both types in one patient is rare [1], but simultaneous existence of PTC and MTC has been reported for at least 70 cases with a variety of presentations [4–6]. In cases of mixed tumor of PTC and MTC, morphological examination shows features of both accompanied by immunological reactivity to calcitonin and thyroglobulin [2]. However, the presence of PTC in the thyroid gland along with an ectopic thyroid gland with MTC is uncommon and rarely reported. This case report will add to the literature and emphasize the important roles of the treating physician and pathologist to avoid mismanagement.

Case report

A 45-year-old male, medically and surgically free, presented to the clinic with a large firm-to-hard, irregular supraclavicular mass in the left lobe of the thyroid, which began 4 months previously with no systemic manifestations. The patient had been on painkillers and antibiotics with no improvement.

Ultrasound and CT scan of the neck revealed a 7 × 4 × 5 cm mass. Fine needle aspiration biopsy of the nodule on the left supraclavicular lymph node revealed a reactive lymphadenopathy with a polymorphous population that included varied sizes, cleaved and non-cleaved lymphocytes, immunoblasts, macrophages, and small mature lymphocytes in a single arrangement, suggestive of chronic reactive follicular hyperplasia. All other routine investigations were within normal range. However, malignancy could not be ruled out.

The patient signed a consent for total thyroidectomy and left modified radical neck dissection along with central neck dissection. Specimens consisted of two pieces of gray-tan firm tissue, the larger measuring 6.0 × 4.0 × 3.0 cm, and the smaller measuring 2.0 × 2.5 × 1.5 cm. Surgical histopathology of the specimens showed a PTC plus isolated MTC. Immunohistochemistry was positive for tumor markers including calcitonin (Ctn), carcinoembryonic antigen, chromogranin A, and synaptophysin.

A total of three specimens were obtained. The first sample, labeled “thyroid,” was a PTC. The right lobe measured 5.5 × 3 × 1.5 cm, the left lobe measured 3.5 × 2.5 × 1 cm, and the isthmus measured 2.5 × 0.5 cm. The outer surface was smooth and firm-to-hard in consistency. The specimen weighed 18 g. Upon gross examination, the upper to lower pole revealed a brownish homogeneous firm-to-hard tissue occupying almost the entire thyroid gland. There was a whitish nodule measuring 1 cm occupying the middle of the right and left lobes and isthmus.

The second sample, labeled “Left neck mass,” was found to be an ectopic thyroid tissue with MTC. It consisted of fibro-fatty tissue with the internal jugular vein. It measured 16 × 10 × 2 cm, and part of the jugular vein measured 7 × 1 cm. The third sample, labeled “central compartment tissue,” consisted of central lymph nodes with PTC measuring 3 × 2 × 1 cm.

The patient was doing well postoperatively, and the course was uneventful. He was discharged home on Day 10 after surgery. He was followed for 2 years after the operation, he was doing well, without any signs of recurrence.

Discussion

Identification of PTC and MTC has increased in recent years [5]. The prevalence of PTC in thyroid gland been widely reported [7]. We believe that this is the first reported case of PTC along with ectopic thyroid with MTC. The peculiarity of this case lies in the occurrence of both PTC and ectopic MTC with a good prognosis over the years, and no recurrence over the years post-surgery.

The presence of two malignant tumors in the same tissue at the same time is unusual, as they arise from different types of cells with well-known distinctive embryogenic origin [8]. Various hypotheses have been presented to explain the coexistence of two different tumors. It been described in the literature as a collision tumor, defined as the presence of two independent cancers that are considered primary events [5]. In this case, the two tumors occurred in different locations of the thyroid tissue with no overlapping tissue. The literature does not discuss the frequency of this unique coexistence of PTC and MTC. Therefore, it is unclear if the coexistence of these cancers is a unique one or only a casual event. Moreover, genetic analysis indicates conflicting results. A sequence analysis published in 2017 showed that the classical point mutation oncogenes shared no link between PTCs and MTCs [2]. Another theory regarding the occurrence of one solid organ malignancy is the “common stem cell theory” that was proposed by Ljungberg, raising the possibility that the cancers might share a common progenitor cell in which the ultimobranchial body undergoes differentiation, giving rise to parafollicular and follicular cells [9].

In conclusion, we present a case report of synchronous appearance of PTC along with ectopic MTC. Physicians and pathologists should be aware of the possibility of such cases to preclude possible misdiagnosis.

Conflict of interest statement

Authors have no conflict of interest to declare.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

References