Fox Chase Cancer Center and Temple Researchers Highlight Need For Molecular Testing in Diagnosing Two Types of Kidney Cancer

PHILADELPHIA (August 5, 2025) — Genetic testing may be the most effective way for researchers to distinguish between a rare form of kidney cancer and another that is more common, potentially preventing misdiagnoses, according to a recent study by researchers at Fox Chase Cancer Center and Temple University Hospital.

Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare subtype of kidney cancer that is characterized, as its name states, of tubules, spindle cells, and mucinous connective tissue. Papillary renal cell carcinoma (PRCC), which is a more common type of kidney cancer, is typically identified by the presence of finger-like projections called papillae.

“Typically, papillary formation in mucinous tubular and spindle cell carcinoma is not a common finding. However, in this study we found papillary formation in all five cases of MTSCC,” said Shuanzeng “Sam” Wei, MD, PhD, senior author and Associate Professor in the Department of Pathology and Medical Director of the Clinical Genomics Laboratory at Fox Chase.

Wei said the finding is striking because papillary formations have previously been the marker for determining whether a tumor is diagnosed as PRCC. However, because papillary formations have now been found in MTSCC cases, diagnosis of these rare tumors is more complicated, especially when using sample methods like fine needle aspiration. These common features mean it is necessary for researchers to do molecular testing in order to make a definitive diagnosis of either MTSCC or PRCC.

In this study, Wei worked with lead author Samir Amer, MD, PhD, a fourth-year resident and chief resident in the Department of Pathology at Temple University Hospital. The research team, which included others at Fox Chase and Temple, compared five cases of MTSCC with papillary formation with 18 cases of PRCC. Chromosomal analysis was then performed to confirm the diagnosis. 

“We want to stress that molecular testing is very useful to distinguish MTSCC from PRCC on a small specimen, and an accurate diagnosis means a better, more effective treatment plan for the patient.”

Wei said further research is needed to determine whether all MTSCC tumors have similar clinical and molecular findings.

The study, “Mucinous Tubular and Spindle Cell Carcinoma With Papillae: A Report of 5 Cases and Comparison With 18 Cases of Papillary Renal Cell Carcinoma,” was published in Human Pathology. # # #