A Rare Case of Metastatic Uterine Leiomyosarcoma to the Thyroid Gland

Abstract

Uterine leiomyosarcomas are malignant tumors that have a grim prognosis. These neoplasms have a high metastatic potential. Limited literature exists on leiomyosarcoma metastasizing to the thyroid. This case emphasizes the importance of considering metastasis as a possible cause for thyroid swelling in patients with a history of malignancy.

Introduction

Metastases to the thyroid gland are uncommon in clinical practice [1]. About 2–3% of malignancies metastasize to thyroid [2]. The most common cancers that metastasize to the thyroid are adenocarcinomas of the kidney, breast, and lungs, as well as head and neck cancers. Leiomyosarcoma tends to spread to distant sites like the lungs, liver, brain and bones [2, 3]. Metastatic uterine leiomyosarcoma to the thyroid, accounting for only 1% of cases worldwide [1]. Metastatic cases in thyroid glands are limited by iodine and oxygen levels [4]. We report a rare case of metastatic uterine leiomyosarcoma to the thyroid gland to highlight the importance of considering metastatic thyroid disease in patients with malignancy.

Case Report

A 45-year-old woman presented with a rapidly growing thyroid swelling of 4 months without major symptoms. She had a history of total abdominal hysterectomy with bilateral salpingo-oophorectomy 3 years back for abnormal uterine bleeding. Histopathology was suggestive of uterine leiomyosarcoma.The patient developed lung metastases 1 year later and was treated with 12 cycles of chemotherapy using docetaxel and gemcitabine. Then she underwent a right lower lobectomy, histopathology was suggestive of metastatic high-grade sarcoma. After 6 months following metastatectomy, she underwent further evaluation for thyroid swelling.

On examination, there was a hard thyroid swelling without any cervical lymphadenopathy (Fig. 1a). An ultrasound of the neck showed TIRADS IV lesion in the left lobe of the thyroid gland. FDG-PET scans revealed metastatic deposits in the thyroid gland. FNAC of the thyroid was suggestive of malignancy (Fig. 1d). An image-guided core biopsy of the thyroid swelling revealed a malignant neoplasm with spindle cell characteristics. Immunohistochemistry (IHC) showed positive staining for smooth muscle actin, vimentin, and desmin (Fig. 2a, b). The diagnosis of metastatic leiomyosarcoma was made based on morphological and immunohistochemical findings (Fig. 2a–e).

Fig. 1.

a Thyroid swelling of the patient. b Sagittal section of head and neck showing enlarged thyroid gland. c CECT of thorax showing metastatic deposits in lower lobe of right lung. d Thyroid nodule FNAC- Marked cellularity of atypical spindle cells.

Fig. 2.

a IHC depicting diffuse SMA positivity. b IHC depicting diffuse desmin positivity. c IHC depicting negative TTF1. d IHC depicting negative Calcitonin. e Histopathology showed pleomorphic tumor cells with large irregular nuclei and coarse chromatin.

The patient underwent a restaging workup with a CECT of the neck and thorax prior to thyroidectomy. CT scan showed progression of thyroid lesion with new pleural-based deposits and locally infiltrating right upper lobe lung lesion, indicating recurrent advanced metastatic disease (Fig. 1b, c). After a multidisciplinary evaluation, the patient with advanced recurrent metastatic disease was planned for palliative treatment.

Discussion

When assessing a patient who has developed swelling in the thyroid and has a history of malignancy, it is important to consider the possibility of metastasis [2, 5]. We present a rare case of uterine leiomyosarcoma metastasis to the thyroid gland, accounting for less than 0.1% of thyroid malignancies [5]. Uterine leiomyosarcomas are aggressive tumors that tend to spread through blood vessels. There have been fewer than 10 reported cases of metastatic uterine leiomyosarcoma to the thyroid [1, 3].

The clinical presentation of the metastatic lesion resembles that of primary thyroid tumors [4]. Patients with metastatic involvement in the thyroid gland often present with a palpable mass in the thyroid area, with or without obstructive symptoms [1]. The sudden thyroid swelling following the exclusion of a primary tumor diagnosis suggests secondary involvement of the thyroid gland [1]. Metastatic thyroid nodules from uterine leiomyosarcoma have been documented, showing hypoechoic solid nodules on ultrasound and infiltrative features on CT scan. These metastatic nodules also demonstrated increased 18 F-FDG uptake in PET/CT scanning, which can also aid in evaluating patients who may require surgical intervention [6].

According to Nemenqani et al., relying solely on clinical examination and radiographic imaging is inadequate for distinguishing between primary and secondary malignancies [7]. Diagnosing secondary thyroid malignancies through fine needle aspiration cytology can be quite challenging as they may mimic primary thyroid neoplasms.

Metastatic leiomyosarcoma and Anaplastic thyroid carcinoma are two entities that may have distinct clinical presentations although they may be similar cytologically [5]. In order to arrive at a diagnosis, it is crucial to perform either a total thyroidectomy or core biopsy, supported by immunohistochemistry [2, 8]. We performed image guided core biopsy for this patient. Cytokeratin-negative staining aids in excluding anaplastic carcinoma, while positive staining for desmin, SMA, and vimentin further supports a diagnosis of leiomyosarcoma. Additionally, there is no expression of TTF1, thyroglobulin, or calcitonin [8]. Preoperative identification of metastatic leiomyosarcoma presents a notable challenge. A multidisciplinary team of specialists including radiologists, pathologists, and surgeons is essential for diagnosis and management. The patient’s relevant clinical and past medical history, as provided by the physician in conjunction with radiological findings, are valuable sources of information for aiding pathologists in reaching a final diagnosis.

The treatment for metastatic thyroid lesions can be surgical or non-surgical, depending on the individual case. Palliative treatment was preferred due to unresectable lung metastasis and aggressive tumor biology. Total thyroidectomy or lobectomy are performed to control local disease and achieve long-term cure in selected patients. The decision to choose between surgical treatment and palliative care for thyroid metastasis depends on factors such as the patient’s performance status, comorbidities, and tumor biology. In most cases, palliative care is the treatment of choice [4]. A significant proportion of patients with metastatic thyroid involvement exhibit multi-organ metastases, ranging from 35 to 80%. [4]

Conclusion

Uterine leiomyosarcoma is a rare tumor that can metastasize to the thyroid gland. The possibility of metastatic thyroid should be considered in patients with a history of malignancy and thyroid swelling. Treatment options may include thyroidectomy or palliative therapies based on the primary tumor’s prognostic factors and the patient’s overall performance status.

Abbreviations

TIRADS

Thyroid imaging reporting and data system

FDG-PET

Fluorodeoxyglucose Positron emission tomography

FNAC

Fine needle aspiration cytology

TTF-1

Thyroid transcription factor 1

SMA

Smooth muscle actin

IHC

Immunohistochemistry

Funding

Nil.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

None.