Pulmonary metastasis of a papillary thyroid carcinoma and primary lung adenocarcinoma: two coincident carcinomas at the same location

Abstract

Tumor-to-tumor metastasis is a fairly rare phenomenon. The lung cancers are the most common donors, but are exceedingly rare as recipients. Here we report a case of a lung adenocarcinoma acting as the recipient of papillary thyroid carcinoma, with multiple spreading foci of the two cancers in the lung simultaneously. The morphology and immunohistochemistry (Napsin-A, Thyroglobulin) are very important in differential diagnosis of lung primary adenocarcinoma and metastatic papillary thyroid carcinoma.

Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2069496615891134.

Figure 1

PET-CT imaging features and macroscopic features. CT revealed a large lobular mass in the superior lobe of left lung. The largest dimension of the mass is 3.2 cm. It invaded the anterior segment and superior segment of the left lung, and invaded pleura mediastinalis. The imaging of the rest lung looks normal (a). PET and CT fusion image showed the nodule had intense FDG uptake. The SUVmaxs was 5.2, which suggested a malignant tumor on PET-CT, and probably lung primary cancer (b). Gross examination showed a tumor (▲) in the peripheral of the lung, with the largest diameter of 3.5 cm. The cut section surface of the tumor was hard, grey and fine granular, and there were many small grey nodes (arrows) in the rest lung, with a diameter of 0.1 cm to 0.3 cm (c). There were plenty of small nodes (arrows) on the visceral pleura (d).

Figure 2

Microscopic features of the metastatic papillary thyroid carcinoma and primary lung adenocarcinoma. Metastatic papillary thyroid carcinoma (→) and primary lung adenocarcinoma (▲) were mixed with each other.

Figure 3

Microscopic features of the metastatic papillary thyroid carcinoma and primary lung adenocarcinoma. The typical papillary pattern, ground glass nuclei, groove and colloid were found in metastatic papillary thyroid carcinoma (a, b). The tumor was mainly consisted of acinar pattern in primary lung adenocarcinoma. Micro-papillary and leptic (bronchioloalveolar carcinoma) patterns can also be seen (c, d, e, f). In the other area of the lung, the two tumor components, metastatic papillary thyroid carcinoma (→) and lung adenocarcinoma (▲), spread simultaneously. They were mixed with each other (g, h). Metastatic carcinoma in the lymph nodes was lung adenocarcinoma (i).

Figure 4

Immunohistochemical features of the metastatic papillary thyroid carcinoma and primary lung adenocarcinoma. Napsin A was positive in primary lung adenocarcinoma (▲), but negative in metastatic papillary thyroid carcinoma (→) (a, b and c). Thyroglobulin was positive in metastatic papillary thyroid carcinoma (→), but negative in primary lung adenocarcinoma (▲) (d, e and f).