# Charting New Territory With a Novel WHO Provisional Category: A Case Study of a Low-Grade Oncocytic Tumor (LOT) in the Kidney

## TL;DR

This paper presents a case study of a rare kidney tumor, LOT, highlighting its unique features and favorable prognosis to guide better patient management.

## Contribution

The paper contributes a detailed case study of a newly classified WHO kidney tumor, emphasizing its distinct clinical and pathological characteristics.

## Key findings

- LOT is a distinct oncocytic tumor with CK7 expression and no CD117 expression.
- LOT typically presents as a small, solitary lesion with a low stage and indolent clinical course.
- The case study shows a favorable one-year follow-up, supporting conservative management strategies.

## Abstract

A low-grade oncocytic tumor of the kidney (LOT) is a distinctive entity categorized under the 2022 World Health Organization (WHO) classification as "Other oncocytic tumors of the kidney.” It represents a unique subset of oncocytic tumors, distinct from oncocytoma and chromophobe renal cell carcinoma. Characterized by bland oncocytic cells that diffusely express CK7 and lack CD117 expression, LOT typically manifests as a solitary, small lesion with a low stage. Available data suggest that LOT follows an indolent clinical course. Herein, we present a case of LOT in a 64-year-old male with a favorable course at a one-year follow-up. Understanding the clinical, morphological, and immunophenotypic features of LOT is paramount for accurate identification and characterization. This knowledge facilitates more conservative surgical and clinical management, optimizing patient care and outcomes.