Lobular Breast Carcinoma Metastasis to the Thyroid Gland: Case Report and Literature Review

Occult breast cancer metastasis to the thyroid gland: Case report

Thyroid metastases of occult breast cancer are very rare. A 48‐year‐old female patient presented with chronic bone pain, bone, liver and thyroid nodules, and pleural effusion. Histopathological result of the thyroid showed poorly differentiated papillary thyroid carcinoma. However, clinical laboratory and immunohistochemistry studies showed breast origin of the thyroid lesion.

Any thyroid mass may be a secondary neoplasm and occult breast cancer should also be considered among the primary sources in spite of its rarity. Immunohistochemistry can play an important role in detecting the origin of malignancy.

Clinicopathological and Molecular Features of Secondary Cancer (Metastasis) to the Thyroid and Advances in Management

Secondary tumours to the thyroid gland are uncommon and often incidentally discovered on imaging. Symptomatic patients often present with a neck mass. Collision tumours of secondary tumours and primary thyroid neoplasms do occur. Ultrasound-guided fine-needle aspiration, core-needle biopsy, and surgical resection with histological and immunohistochemical analysis are employed to confirm diagnosis as well as for applying molecular studies to identify candidates for targeted therapy. Biopsy at the metastatic site can identify mutations (such as EGFR, K-Ras, VHL) and translocations (such as EML4-ALK fusion) important in planning target therapies. Patients with advanced-stage primary cancers, widespread dissemination, or unknown primary origin often have a poor prognosis. Those with isolated metastasis to the thyroid have better survival outcomes and are more likely to undergo thyroid resection. Systemic therapies, such as chemotherapy and hormonal therapy, are often used as adjuvant treatment post-operatively or in patients with disseminated disease. New targeted therapies, such as tyrosine kinase inhibitors and immune checkpoint inhibitors, have shown success in reported cases. A tailored treatment plan based on primary tumour features, overall cancer burden, and co-morbidities is imperative. To conclude, secondary cancer to the thyroid is uncommon, and awareness of the updates on diagnosis and management is needed.

Application of Immunohistochemistry in Papillary Thyroid Carcinoma

Immunohistochemistry (IHC) is an economic and precise method to localize the presence of specific protein at cellular level in tissue. Although many papillary thyroid carcinomas do not require IHC to render a diagnosis, there are certain scenarios in which IHC are important. The major diagnostic applications of IHC include confirmation of papillary thyroid carcinoma in sites other than the thyroid, distinguish papillary thyroid carcinoma from other primary thyroid neoplasms in thyroid, and identify papillary thyroid carcinoma from secondary tumors to the thyroid. At research level, IHC could help identify prognostic information, identify underlying genetic alterations, and predict response to treatment in papillary thyroid carcinoma. The understanding of principle and recent advances in IHC will improve the diagnosis and management of patients with thyroid lesions including papillary thyroid carcinoma.

Case Report and Review of Literature: Thyroid Metastases From Breast Carcinoma

RATIONALE

The thyroid is a rare site for distant metastases from breast carcinoma. The incidence of thyroid metastases in fine needle aspiration biopsy (FNAB) was less than 0.2%.

PATIENT CONCERNS

We report a case of 54-year-old woman with a history of breast carcinoma presented with diffuse scattered microcalcifications in thyroid and enlarged bilateral cervical lymph nodes detected on ultrasound (US). Physical examination of the patient revealed firm and enlarged thyroid lobes.

DIAGNOSES

FNAB and immunohistochemistry (IHC) of the thyroid lesion confirmed the thyroid metastases from breast cancer.

INTERVENTIONS AND OUTCOMES

Due to the comorbidities of breast carcinoma metastases to the right axillary, cervical lymph nodes and left chest wall, the patient received chemotherapy. After a follow-up of 19 months, the patient was alive without any new distant metastases.

LESSONS

Our case highlights that thyroid metastases should be considered in a patient combined with thyroid lesions and a history of breast carcinoma. IHC played an important role in differentiating thyroid metastases from primary thyroid cancer.

Thyroid metastasis from breast cancer presenting with enlarged lateral cervical lymph nodes: A case report

BACKGROUND

Secondary malignancy of the thyroid occurs infrequently and mainly originates from malignant tumors of the kidney, gastrointestinal tract, lungs, breast, and skin. The correct diagnosis is important but difficult. Importantly, there are major differences in the treatment of primary and metastatic thyroid cancer, which has a significant impact on prognosis and survival. Therefore, how to diagnose thyroid metastasis (TM) correctly before surgery is a major concern for surgeons.

CASE SUMMARY

We report a 38-year-old woman who presented with palpable cervical lymph nodes after breast cancer (BC) surgery 2 years ago. Ultrasonography and computed tomography revealed thyroid nodules with irregular margins and enlarged cervical lymph nodes. Biopsy was performed for the right largest cervical lymph node, and immunohistochemical analysis revealed negativity for thyroglobulin, estrogen receptor, and progestin receptor and positive for human epidermal growth factor receptor 2. The diagnosis was TM from BC with cervical lymph node metastasis. Total thyroidectomy with bilateral central and lateral neck lymph node dissection was performed. After a 5-mo follow-up, no recurrence or novel distant metastasis was identified.

CONCLUSION

TM from BC is a rare secondary malignancy. Broad differential diagnosis by biopsy and immunohistochemical analysis needs to be considered.