Tumor-to-Tumor Metastasis: Lung Carcinoma Metastasizing to Thyroid Neoplasms

Figure 1

(a) Within the encapsulated follicular adenoma is an abrupt transition to a morphologically distinct neoplasm (magnification ×40). (b) Metastatic carcinoma is arranged in sheets with hyperchromatic nuclei and scanty cytoplasm infiltrating the follicular adenoma (magnification ×200). (c) The metastatic carcinoma is negative for thyroglobulin, while the adenoma is strongly positive (magnification ×100). (d) Synaptophysin is strongly positive in the metastatic carcinoma (magnification ×200).

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