Lung adenocarcinoma with thyroid metastasis: a case report

BACKGROUND: The metastases of a primary lung cancer over the thyroid gland are extremely rare. We report on an unusual presentation of thyroid metastasis of lung cancer in order to improve the management of similar cases. CASE PRESENTATION: Three years ago, a Moroccan male 59-year-old was admitted for dyspnea, dry cough, and chest pain. He had smoked about 30 cigarette packs a year. Clinical examination revealed a right thyroid nodule. Chest and neck computed tomography (CT) scan showed a proximal left tumor in contact with the pulmonary artery and revealed a suspected nodule in the right lobe of the thyroid with homolateral neck node. Transbronchial biopsy was performed and pathological examination revealed adenocarcinoma of the lung and positive for thyroid transcription factor. Other explorations carried out, such as brain CT, bone scan and abdominal ultrasound were normal. After a repeated negative fine needle aspiration biopsy of the suspected nodule of the right lobe of the thyroid, we performed total thyroidectomy with neck dissection. An anatomopathologic exam revealed a tubulopapillary adenocarcinoma poorly differentiated. An Immunohistochemistry showed positive tumor cells with TTF1 and cytokeratin (CK) 7 but negative cells with thyroglobulin and CK20. Thus, the pulmonary tumor was classified stage IV. Chemotherapy based on the combination of cisplatin and etoposide was conducted along with supportive care. The tumor grew up with brain metastases after three cycles of chemotherapy. Unfortunately, the patient died 2 months after despite brain radiotherapy. CONCLUSION: We presented a medical case of a patient with thyroid metastasis resulting from a pulmonary adenocarcinoma which has rapidly evolved to brain metastases. The prognosis was pejorative in our clinical case (5 months after admission).