Diffuse thyroid enlargement following metastasis of lung adenocarcinoma

Metastatic lung carcinoma in thyroid aspirates: A case series and literature review illustrating diagnostic challenges

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common primary malignant thyroid neoplasm and malignant diagnosis in thyroid aspirates. Metastatic adenocarcinoma of lung is an under-recognized mimicker which overlaps cytomorphologically and immunocytochemically with PTC. This case series reviews thyroid aspirates of metastatic lung carcinomas, aiming to address the similarities and methods of differentiating this entity from PTC.

METHODS

Thyroid aspirates of metastatic lung carcinomas were obtained by a computerized search. Clinico-cytological features and ancillary test results were reviewed. Literature review was performed for published cases of metastatic lung carcinomas in thyroid aspirates.

RESULTS

A total of 14 cases were found, including nine adenocarcinomas, three TTF1-positive non-small cell lung carcinomas (NSCLCs), one small cell carcinoma and one squamous cell carcinoma. The adenocarcinomas and TTF1-positive NSCLCs displayed PTC-like features including papillae/papillary-like fronds (n=6/12, 50%), nuclear grooves (n=5/12, 41.7%) and inclusions (n=1/12, 8.3%), chromatin clearing (n=3/12, 25%), calcifications (n=3/12, 25%) and multinucleated giant cells (n=2/12, 16.7%). Useful distinguishing features observed were prominent nucleoli, coarse chromatin, mitosis, and necrosis. TTF-1 immunocytochemistry was positive in most cases (n=5/6, 83.3%), while PAX8 and thyroglobulin were consistently negative. EGFR exon 19 deletion was detected on cell block preparation in a single case, corresponding to its lung primary. Literature search yielded 84 cases of metastatic malignancies, with lung carcinomas comprising of 3.6%-33.3% in case series of metastatic malignancies.

CONCLUSION

Metastatic adenocarcinoma of lung and PTC share significant cytomorphological and immunocytochemical similarities. A high degree of caution, meticulous clinico-cytological assessment and prudent use of ancillary techniques is necessary to avoid potential misdiagnosis.

A rare case of lung cancer presenting as an ischioanal fossa mass

Lung cancer metastasis commonly involves the adrenal glands, liver, bone, and brain. However, it can have some rarer forms of metastatic presentation making diagnosis difficult, especially in nonsmokers. We describe a rare case of lung cancer with metastasis to the ischioanal fossa. Overall, this case emphasizes that consideration should be given to wide range of diagnosis in atypical cases of anorectal masses. Lung cancer presenting as an ischioanal mass is not reported so far.

Case report: Diffuse metastatic infiltration of the thyroid by esophageal adenocarcinoma mimicking non-neoplastic thyroid disease

We report a patient who suffered from esophageal cancer that metastasized to the thyroid. There are only a handful of cases of esophageal cancer with metastases to the thyroid reported in the literature. To our knowledge, this is the first with a diffusely infiltrative pattern (the others were focal masses/nodules). This diffusely infiltrative pattern of metastatic disease is important for radiologists to be aware of because it is particularly difficult to detect and is not characteristically neoplastic by pattern. A diffuse parenchymal abnormality that is bilaterally symmetric is more commonly associated with non-neoplastic diffuse thyroid disease, such as autoimmune thyroid diseases (eg, Graves' disease). As such, in addition to the more common non-neoplastic differential diagnoses associated with diffuse thyroid disease, a diffuse thyroid parenchymal abnormality in a patient with a history of esophageal carcinoma should raise the question of diffuse metastatic infiltration.

Ultrasound findings of diffuse metastasis of gastric signet-ring-cell carcinoma to the thyroid gland

It has been shown that metastases to the thyroid from extrathyroidal malignancies occur as solitary or multiple nodules, or may involve the whole thyroid gland diffusely. However, diffuse metastasis of gastric cancer to the thyroid is extremely rare. Here, we report a case of a 74-year-old woman with diffuse infiltration of gastric adenocarcinoma (signet-ring-cell carcinoma/poorly differentiated adenocarcinoma) cells in the thyroid. The pathological diagnosis was made based on upper gastrointestinal endoscopy with biopsy and fine-needle aspiration cytology of the thyroid. An 18F-FDG PET/CT revealed multiple lesions with increased uptake, including the bilateral thyroid gland. On thyroid ultrasound examination, diffuse enlargement with internal heterogeneity and hypoechoic reticular lines was observed. On color Doppler imaging, a blood-flow signal was not detected in these hypoechoic lines. These findings were similar to those of diffuse metastases caused by other primary cancers, such as lung cancer, as reported earlier. Therefore, the presence of hypoechoic reticular lines without blood-flow signals is probably common to diffuse thyroid metastasis from any origin and an important diagnostic finding. This is the first report to show detailed ultrasound findings of diffuse gastric cancer metastasis to the thyroid gland using color Doppler.