1 INTRODUCTION
Renal cysts are commonly encountered in clinical practice, often benign and asymptomatic[
1]. However, in some cases, they may harbor pathological entities such as neoplasms. Mixed epithelial and stromal tumors (MESTs) are an uncommon subtype of renal tumors, often presenting with nonspecific symptoms such as flank pain, hematuria, or palpable mass[
2]. Imaging studies are crucial for accurate diagnosis and management planning[
2]. While laparoscopic deroofing is a well‐established approach for symptomatic renal cysts, the finding of a MEST within such a cyst is exceedingly rare[
3,
4].
We present a unique case of a mixed epithelial and stromal renal tumor masquerading as a lower pole renal cyst. This case report aims to discuss the diagnostic and management approaches employed, particularly focusing on the successful utilization of laparoscopic deroofing.
To our knowledge, this is the first ever case of histologically proven MEST after laparoscopic deroofing.
2 CASE PRESENTATION
A 37‐year‐old female presented with persistent left flank pain, without any associated urinary or digestive symptoms. Bedside ultrasound revealed a large, oval‐shaped hypoechoic mass on the lower pole of the kidney, measuring 90 mm in its long diameter, with a thin wall and no obvious debris. Urine and blood tests all showed normal results within the expected ranges.
Computer tomography with intravenous contrast revealed a large renal cyst in the lower pole of the left kidney classified as Bosniak 2 due to its size (83 mm × 88 mm) (Figure 1). Due to the patient's persistent symptoms despite analgesia, a laparoscopic deroofing procedure was performed under general anesthesia using three ports. The renal cyst's wall was carefully dissected and deroofed, allowing visualization of fluid and no solid components within the cystic lesion (Figure 2A–D). Complete excision of the cyst roof and meticulous hemostasis were achieved. The specimen was extracted intact using an endobag. Histopathological examination revealed a MEST arising from the renal cortex. The epithelial component showed benign tubules, while the stromal component exhibited cellular spindle‐shaped cells (Figure 3A–C). There was no evidence of malignant transformation or vascular invasion. The patient was followed up for 3 months postprocedure and reported complete resolution of left flank pains.
3 DISCUSSION
MEST predominantly affect middle‐aged females and often present as complex renal cysts. Accurate preoperative diagnosis is challenging due to their cystic appearance on imaging studies[
5].
This case highlights the challenges in diagnosing mixed epithelial and stromal renal tumors, which can mimic benign renal cysts as well as the importance of thorough investigation and consideration of atypical aetiologies in patients with longstanding symptoms attributed to renal cysts[
6,
7]. The successful management through laparoscopic deroofing emphasizes the importance of using minimally invasive techniques for diagnosis and treatment.
The finding of a MEST in this context raises questions about the pathogenesis and appropriate management of such tumors, especially in young female patients[
8]. This case also prompts consideration of the need for close surveillance of renal cysts, even if they remain stable in size over time, to avoid overlooking potential neoplastic transformations[
9,
10].
The significance of laparoscopic deroofing as a diagnostic and therapeutic tool in managing renal cysts is underscored by this case. Surgical intervention is normally warranted for symptomatic or potentially malignant lesions[
3]. In our case, laparoscopic deroofing provided both diagnostic and therapeutic benefits, enabling complete resection of the tumor while preserving renal function.
Furthermore, the histopathological identification of rare entities like MESTs distinguishing them from other differential diagnoses such as cystic renal cell carcinoma, cystic nephroma, cystic partially differentiated nephroblastoma, and eosinophilic solid and cystic renal cell carcinoma emphasizes the necessity of interdisciplinary collaboration among urologists, radiologists, and pathologists to optimize patient care[
11].
4 CONCLUSION
We present a first of its kind and unique clinical scenario of a mixed epithelial and stromal renal tumor masquerading as a lower pole renal cyst. Through laparoscopic deroofing, successful identification and surgical management of the tumor were achieved. The rarity of this presentation emphasizes the need to consider MEST as one of the underlying causes in the assessment of renal cysts, particularly in patients with persistent symptoms. This case report contributes to the existing literature by highlighting the importance of considering rare pathological entities in the evaluation of renal cysts and the value of laparoscopic techniques in their management.
2024 The Authors. UroPrecision published by John Wiley & Sons Australia, Ltd on behalf of Higher Education Press.
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