Lung metastases as the first manifestations of occult medullary microcarcinoma

: The article is concerned with medullary microcarcinoma of the thyroid. Similarly to medullary macrocarcinoma, this may metastasize to distant sites. Reported is a case of a 54year- old male who had suffered from chest tightness and dry irritating cough. Chest Xray showed small nodules with poorly- defined borders of unknown etiology. Lung biopsy was performed, which detected amyloid- rich neuroendocrine carcinoma. Examination of the thyroid was recommended to confirm or rule out suspected medullary carcinoma. The biopsy examination also suggested G1 and G2 primary neuroendocrine carcinoma of the lung or diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. Numerous examinations using imaging methods (CT, MRI, PET- CT) were carried out with no positive results in the thyroid. Despite that, thyroidectomy was performed. Subsequent biopsy examination revealed medullary microcarcinoma sized 0.6 cm. Apart from lung metastases, tumor lesions were found in cervical lymph nodes. This case is an example of a close cooperation between a pathologist and a clinician -  endocrinologist. Based on serum calcitonin levels, this may aid in differential diagnosis.