Rare localisation of breast cancer metastasis to thyroid gland Retka metastaza karcinoma dojke u tiroidnu žlezdu

Introduction. Metastases to the thyroid gland are very rare. They are usually seen in malignant melanoma, kidney, breast cancer and lung cancer. Case report. We presented a 54years-old female patient with breast cancer diagnosed in 2002. The adequate surgical procedure was done and the tumor and axillary lymph nodes were removed. The patient also received adjuvant postoperative chemotherapy. After seven years of a disease free period, the first relapse of the disease was detected as thyroid gland tumor with axillary lymphadenopathy. The patient had a good response to systemic treatment so the surgical removal of thyroid gland and enlarged lymph nodes was performed. Histopathological analysis confirmed metastasis with breast cancer origin. Radical mastectomy was also preformed. Second relapse of the disease was detected 10 months later, while the patient was on hormonal therapy. It was manifested as the appearance of bone and skin metastases, pleural effusion and lymphadenopathy. Conclusion. This case report emphasized the importance of detailed examination of any new onset of thyroid swelling in a patient with previous history of malignancy.


Introduction
Metastasis to the thyroid gland is usually considered rare 1,2 .The overall incidence in autopsy series has been 0%-1% in unselected autopsy studies and around 24% in patients with metastatic disease [3][4][5][6][7][8] .The most common among metastasizing cancers to the thyroid gland are malignant melanoma, kidney, breast cancer and lung cancer 9 .We presented a female patient with local recurrence of breast cancer and metastasis in the thyroid gland, without any other distant metastases.

Case report
A 54-year-old woman was diagnosed with carcinoma of the right breast in 2002 at the Institute for Oncology and Radiology of Serbia, Belgrade, Serbia.After initial biopsy, tumorectomy with axillary dissection was performed in stage T2N1.Histopathological analysis confirmed ductal carcinoma with lobular component.Oestrogen receptors were 30% positive, progesterone 10% and HER2/neu was negative at immunohistochemistry. Malignant cells were found in one out of nine lymph nodes.The patient received six cycles of adjuvant chemotherapy with CMF protocol, containing cyclophosphamide, methotrexate and 5-fluorouracil.Postoperative radiotherapy was also administered.
The patient was followed up every six months for the period of seven years.No local or distal recurrence was found until the beginning of 2009, when the first relapse of the disease was detected as local recidive in the right breast with both side axillary lymphadenopathy.At that time, Estern Corporative Oncology Group/World Health Organization (ECOG/WHO) performance status of patient was 0. The treatment was continued with systemic chemotherapy according to FAC regimen (5-fluorouracil, doxorubicin and cyclophosphamide).After the first cycle of chemotherapy, thyroid gland became physically palpable so additional examination was done.Ultrasonography showed low density, 3 cm sized nodule in the left lobe of the thyroid gland, with no calcification.The thyroid hormone levels in blood were within normal ranges.The patient did not have any symptoms such as dyspnoea or wheezing present.After six cycles of chemotherapy, loboisthmectomy was performed in June 2009.Biopsy ex tempore showed metastatic breast cancer cells in thyroid gland tissue (Figure 1).Definite histopathological confirmed two foci of breast cancer metastasis.In addition, immunohistochemical analysis confirmed: oestrogen receptor (ER) Allred score 8, progesteron receptor (PR) score 7, HER2/neu 1+ (Figure 2), CK7+, CK19+.The tests were negative for thyroid transcription factor-1 (TTF-1) (Figure 3), tireoglobuline, vimentine and monoclonal antibody HBME-1.The struma was also seen.During surgical procedure, enlarged lymph nodes were removed and breast cancer metastases were also found in 3/5 supraclavicular and 2/3 jugular lymph nodes.The treatment was continued with six cycles of weekly paclitaxel and hormonal therapy tamoxifen.After the partial response was achieved, radical mastectomy of the right breast was performed in April 2010.Histopathology confirmed invasive lobular carcinoma grade 2, ER score 8, PR score 7, HER2/neu negative (score 1+) (Figure 4).The patient continued to be on hormonal therapy until March 2011 when the new evaluation of the disease was performed.Computed tomography body scan (PET CT) showed multiple metastases in bones.Chest radiography revealed pleural effusion.Cutaneous lenticular metastases and axillary lymphadenopathy were seen on clinical examination.The only symptom that the patient reported was pain in the lower spine.ECOG/WHO performance status was 1.The patient was presented to a multidisciplinary team at the Institute for Oncology and Radiology of Serbia.It was decided to interrupt tamoxifen and continue the treatment with aromatase inhibitors.Palliative radiotherapy of the cervical spine and pelvis bones was also planned.

Discussion
The incidence of metastatic disease to the thyroid gland has been reported to be 0%-1% in unselected autopsy studies and around 24% in patients with confirmed metastatic disease 3-8 .As a result of the lack of awareness among clinicians, clinical diagnosis is even less common than postmortem findings.
Although the thyroid gland could be the only site of malignant disease, usually most of patients with thyroid metastases have widespread metastatic disease.Therefore, detection of metastasis to the thyroid gland often indicates poor prognosis.In a small percentage of patients, early diagnosis and aggressive surgical or medical therapy probably may be effective and contribute to the prolonged survival [10][11][12] .There is still no precise consensus, but a thyroid lobectomy and/or isthmectomy is recommended in case of solitary metastasis and a total thyroidectomy if thyroid metastases are bilateral 13 .
A long interval between the diagnosis of primary cancer and subsequent thyroid gland metastasis can represent a diagnostic dilemma.Therefore, the standard for all newly incurred thyroid swelling in a patient with previous history of malignancy, regardless the duration of that period, should be considered as recurrence until proved otherwise 14 .In patients with metastases, low performance status and poor prognosis, fine needle aspiration biopsy (FNAB) can be used to detect an unsuspected malignancy and to avoid unnecessary thyroidectomy 7 .

Conclusion
This report emphasizes the importance of detailed examination of any new onset of thyroid swelling, especially in a patient with previous history of malignant disease.