Tumor‐to‐tumor metastasis to a thyroid follicular adenoma as the initial presentation of a colonic adenocarcinoma

Abstract

The incidence of thyroid involvement by metastatic disease from distant organs ranges from an average of 3.1% in surgical series to 5.3% in autopsy series. However, the metastasis of one tumor into another (traditionally referred to as 'tumor-to-tumor metastasis') is distinctly uncommon. Typically, they are identified as new manifestations or necropsy findings of a known, pre-existing donor tumor. Herein is described the case of a 59-year-old woman whose thyroid nodule (a follicular adenoma) was resected and found to contain foci of a well-differentiated adenocarcinoma with a morphologic and immunohistochemical profile consistent with origination from the lower gastrointestinal tract. Subsequent diagnostic work-up revealed a sigmoid colon tumor with metastases to the liver. This is, to the authors' knowledge, the first reported example of a colon adenocarcinoma whose initial clinical manifestation was a metastasis to a thyroid neoplasm and only the third reported example of a colonic adenocarcinoma metastatic to a thyroid tumor. In a review of previously reported examples of tumor-to-tumor metastases involving a thyroid neoplasm as the recipient, the following features were present in the majority: (i) multifocality of the metastatic tumor aggregates; (ii) a total lack of, or only minimal amounts of reaction (desmoplastic, inflammatory or myxoid) of the recipient tumor to the metastatic deposits; and (iii) retention of the histopathologic characteristics of the donor tumor in the metastatic deposits. In general, strikingly divergent morphologic features in an otherwise typical thyroid neoplasm should elicit a differential diagnosis that takes into consideration the possibility of metastasis.

Tumor-to-tumor Metastases to Follicular Variant of Papillary Thyroid Carcinoma: Histologic, Immunohistochemical, and Molecular Studies of Two Unusual Cases

“…Nevertheless, whether tumor-to-tumor metastasis is only an occurrence of chance or is due to selective mechanisms unique to certain neoplasms remains controversial. Several reports have argued that the incidence of metastases to recipient tumors is the same as compared to adjacent normal parenchyma of recipient organ [6], and the donor tumors are present not only in the recipient tumors but also in the normal parenchyma of recipient organ [1,4,25]. However, the metastatic tumors in both cases we present were completely confined to the substance of the recipient tumors (FVPTCs), suggesting that the anatomic lymphovascular mechanism might be a valid theory of the underlying pathogenesis of tumor-to-tumor metastasis in this setting.…”

“…The most common recipient primary tumor in thyroid gland is follicular adenoma (FA, 9/19 cases) [3, 5-9, 11, 12], followed by FVPTC (3/19 cases) [4]. Fadare et al summarized some features shared by the majority of such cases, including multifocality of the metastatic tumor aggregates, scant reaction of the recipient tumor (desmoplastic, inflammatory, or myxoid) to the metastatic deposits, and retention of the histopathologic characteristics of the donor tumor [6].…”

“…The most frequently reported recipient tumor is renal cell carcinoma (RCC, 40-70%), followed by sarcoma, meningioma, thyroid neoplasm, and pituitary adenoma [1,2]. In the English literature, there are only 19 cases of tumor-totumor metastases involving recipient thyroid neoplasms [1,[3][4][5][6][7][8][9][10][11][12][13][14][15]. We present two diagnostically challenging cases of tumor-to-tumor metastases that were resolved by integrating clinical, morphologic, immunohistochemical, and molecular findings.…”

Secondary Lymphoma Involving Metastatic Follicular Thyroid Carcinoma to the Skull: A Unique Example of Tumor-to-Tumor Metastasis

“…Campbell et al defined tumor-totumor metastases with the following criteria: more than one primary tumor must be present, the recipient tumor must be a true neoplasm, the donor tumor must be a true metastasis and not due to contiguous growth or embolization, and metastases to lymphatics are excluded [16]. Donor tumors to thyroid neoplasms from the kidney, lung, colon, breast, prostate, malignant melanoma and pancreas have been reported, with renal cell carcinoma being the most common [5,17,18]. The most frequent type of recipient tumor in the thyroid gland is follicular adenoma [17].…”

Metastatic adenocarcinoma within a functioning adrenal adenoma: a case report

“…Fewer than 100 cases have been reported in the literature. Our institution previously reported a case of a colonic adenocarcinoma metastasizing to a thyroid adenoma [6]. The phenomenon generally involves metastasis from a donor (malignant) tumor to either a benign or malignant recipient tumor.…”