Tumor-to-Tumor Metastasis: Lung Adenocarcinoma as a Recipient of Metastasis from Renal Cell Carcinoma: A Case Report

Abstract

BACKGROUND The occurrence of metastasis from one neoplasm to another is known as tumor-to-tumor metastasis (TTM). It is a rare phenomenon in the natural history of any neoplasm, with approximately 100 cases reported in the literature to date. The lungs are the most frequent metastatic tumor donors and kidney cancer is the most common recipient. However, the opposite phenomenon (lung adenocarcinoma as a recipient of metastasis from renal carcinoma) has not been previously reported in the literature. CASE REPORT We present the case of a man with a history of multiple neoplasms. He had a diffuse large B-cell lymphoma in 2006, a left papillary renal cell carcinoma (RCC) type 2 in 2006, and an acinar adenocarcinoma of the prostate in 2011. A follow-up computed tomography scan in July 2019 showed a suspicious lung nodule on the left upper lobe and a retroperitoneal hypermetabolic mass on the positron emission tomography scan. The lung nodule and retroperitoneal mass biopsies were consistent with a primary lung adenocarcinoma with a lepidic pattern and a metastatic RCC, respectively. In January 2020, he underwent a thoracoscopic left upper lobectomy and a mediastinal lymph node dissection. Histopathological evaluation revealed a 2-cm nodule composed of a lung adenocarcinoma with an intratumoral metastasis from a papillary RCC. To date, the patient has stable renal neoplastic metastatic disease and no locoregional recurrences of the lung adenocarcinoma. CONCLUSIONS Metastasis from one primary tumor to another primary tumor is an extremely unusual event. We report one of the first cases of an RCC metastasis to a primary lung adenocarcinoma.

Figure 1.

A thoracic computed tomography scan showing a pulmonary nodule with mixed solid and ground-glass opacity (21-mm diameter), located in the central aspect of the left upper lobe.

Figure 2.

The moderately differentiated lung adenocarcinoma displayed a 40% solid (white arrow) and 60% acinar (black arrow) pattern (hematoxylin and eosin stain, 4× magnification).

Figure 3.

(A) Intratumoral metastasis of the papillary renal cell carcinoma type 2 measuring 0.2×0.2 cm, surrounded by a lung adenocarcinoma. (B) The circle encloses the intratumoral metastasis (hematoxylin and eosin stain, 10× magnification).

Figure 4.

Immunohistochemical studies with positivity for CKAE1/AE3, CK7, Napsin A, and thyroid transcription factor 1 (TTF-1) in the acinar (60%) and solid (40%) lung adenocarcinoma. Positivity for CKAE1/AE3 and CK7, and negativity for Napsin A and TTF-1 for the metastasis from the papillary renal cell carcinoma (RCC) type 2 metastasis (arrows indicate intratumoral RCC metastasis): (A) CKAE1/AE3 in the lung adenocarcinoma (CKAE1/AE3 stain, 4× magnification). (B) CKAE1/AE3 in the intratumoral metastasis of the papillary RCC type 2 (CKAE1/AE3 stain, 10× magnification). (C) CK7 in the lung adenocarcinoma (CK7 stain, 4× magnification). (D) CK7 in the intratumoral metastasis of the papillary RCC type 2 (CK7 stain, 10× magnification). (E) Napsin A in the lung adenocarcinoma (napsin A stain, 4× magnification). (F) Napsin A in the intratumoral metastasis of the papillary RCC type 2 (napsin A stain, 10× magnification). (G) TTF-1 in the lung adenocarcinoma (TTF1 stain, 4× magnification). (H) TTF-1 in the intratumoral metastasis of the papillary RCC type 2 (TTF-1 stain, 10× magnification).

Figure 5.

Immunomarkers for kidney cells: Positivity in the intratumoral metastasis of the papillary renal cell carcinoma (RCC) type 2, negativity in the periphery corresponding to the lung adenocarcinoma (arrows indicate intratumoral RCC metastasis): (A) RCC marker (RCC stain, 4× magnification). (B) CD10 (CD10 stain, 4× magnification). (C) Paired box gene 8 (PAX8 stain, 40× magnification).