Background
Medullary thyroid carcinoma (MTC) is a rare neuroendocrine primary
thyroid tumor, originating from the parafollicular C-cells of the
thyroid gland. These aggressive cancers constitute approximately 3-10%
of all primary thyroid malignancies, and are mainly sporadic (75%)
[1,2]. Sporadic cases of MTC are usually diagnosed within the fourth
to sixth decades of life and commonly manifest as a solitary thyroid
nodule [3]. In about 5-10% of patients with MTC who have a palpable
thyroid nodule, distant metastatic disease is present at presentation
[1,4,5]. These tumors tend to metastasize to the kidneys, liver,
lungs, bones, and less frequently, to the brain and skin [6,7]. Lung
metastases occur in 33% of patients with locally advanced or metastatic
MTC [8] and usually have a macronodular appearance; however,
calcified pulmonary metastases, reticulonodular perihilar lesions and
micronodular lesions have also been reported in several studies
[9,10]. According to the literature, micronodular densities are more
often associated with papillary thyroid carcinoma [10]. Here, we
report the case of a middle-aged woman with metastatic medullary
carcinoma of the thyroid presenting with an unusual miliary pattern on
chest imaging mimicking that of miliary tuberculosis.