# A Case of Reactive Lymphoid Hyperplasia That Is Difficult to Differentiate From Renal Cancer With Lymph Node Metastasis

## TL;DR

A rare case of kidney reactive lymphoid hyperplasia was mistaken for cancer due to similar imaging features, highlighting the need for biopsy to avoid unnecessary surgery.

## Contribution

First reported case of reactive lymphoid hyperplasia in the kidney with regional lymph node enlargement.

## Key findings

- Reactive lymphoid hyperplasia can mimic renal cell carcinoma on imaging.
- The patient remained recurrence-free without further treatment after surgery.
- Percutaneous biopsy is recommended when cancer diagnosis is uncertain.

## Abstract

Reactive lymphoid hyperplasia (RLH) is a rare benign lymphoproliferative disorder that rarely involves the kidney and has not been reported in association with regional lymphadenopathy.

A 70‐year‐old woman was incidentally found to have a left renal mass. Contrast‐enhanced computed tomography revealed a 20‐mm enhancing renal lesion with enlarged hilar lymph nodes, leading to a preoperative diagnosis of renal cell carcinoma with nodal metastasis (cT1aN1M0). Open radical nephrectomy with regional lymphadenectomy was performed. Histopathological analyses established a diagnosis of reactive lymphoid hyperplasia. No additional treatment was administered, and the patient has remained free of recurrence for 3 months.

We report the first case of RLH accompanied by regional lymph node enlargement. Because RLH can closely mimic renal cell carcinoma on imaging, it should be considered in the differential diagnosis of renal masses when the clinical presentation is inconsistent with typical renal cell carcinoma.

Renal reactive lymphoid hyperplasia is an extremely rare benign condition that can present with regional lymphadenopathy and closely mimic renal cell carcinoma on imaging. When the clinical presentation is inconsistent with typical renal cell carcinoma, percutaneous needle biopsy should be considered, provided it can be performed safely, to avoid unnecessary radical surgery.