“Homomorphic” Tumor Metastases as an Endodiagnostic Clue: A Case Series of Renal-Cell Carcinoma Metastatic to the Stomach

Abstract

Distinguishing between a primary malignancy and a metastasis can be challenging in some cases. Herein, we describe 2 cases of gastric lesions that were endoscopically sampled and ultimately found to be metastatic from a renal-cell carcinoma. In both cases, the gastric metastases were endoscopically homomorphic to the primary organ (the kidney); i.e., grossly resembling and thus providing an endoscopic clue as to the primary tumor source. We report on the evaluation of obscure metastatic gastric involvement of malignancy and present the concept of homomorphism as a potential diagnostic clue in determining the source of unknown and often unsuspected primary malignancy.

Homomorphic Adenocarcinoma Metastases to the Liver: A Report of 2 Cases

“…However, even with this, a primary tumor source can be elusive. Hence, as recently reported [ 1 , 2 ] and as illustrated herein, the presence of tumor homomorphism may allow a clinician to visually link a metastatic lesion to its primary source, thereby providing a unique diagnostic clue.…”

“…Despite the fact that only 3 other cases of “homomorphic” metastases have been reported, we believe this finding is generally overlooked/unrecognized, and thus may in fact be more common, although its pathobiology and prognostic significance remain largely unknown [ 1 , 2 ]. As seen in our series of cases, tumor homomorphism, when recognized, may help expedite targeted diagnostic testing and subsequently provide more timely and cost-effective care.…”

“…Differentiating between the primary and metastatic source and/or site of a malignancy can be challenging despite advances in imaging, tissue sampling techniques, histopathology, and immunohistochemistry [ 1 ]. This can be particularly true in gastrointestinal and hepatobiliary malignancies due to various anatomical factors [ 2 ].…”

“…In both cases, the lesions were ultimately determined to be from metastatic adenocarcinoma (ampullary in the first and colonic in the second) and were curiously “homomorphic” in appearance, i.e., their radiographic appearance resembled a dilated tubular structure akin to the ampulla and a haustrated bowel akin to the colon, respectively. “Homomorphism” is a relatively new and perhaps novel term within the literature, and the finding of tumor homomorphism can be considered as a diagnostic pearl in determining an otherwise unsuspected or uncertain primary source of metastatic disease [ 1 , 2 ].…”

Application of 18F Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography in Monitoring Gastric Metastasis and Cancer Thrombi from Renal Cell Carcinoma

“…We identified 73 cases of RCC with gastric metastasis from literature reviews. Including the patient treated in our hospital, there were 5 cases of RCC with simultaneous solitary gastric metastasis [4,[16][17][18][19] (Table 1), 4 cases with gastric and multiple-site metastases [20][21][22][23] (Table 2), 21 cases with solitary metachronous gastric metastasis [16,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] (Table 3), and 44 cases with metachronous gastric and multiple-site metastases [32, (Table 4).…”