INTRODUCTION:It is a challenge to make accurate pre-surgical diagnosis for renal tumors. This study is to report the findings, management, and outcome of one rare case of ossification in a cystic renal mass. We present and discuss the pathological characteristics, radiologic features, and treatmentalternatives of the patient. PATIENTS AND METHODS:A 38 years old female patient had intermittent epigastric pain and microscopic hematuria for two months. Computerized tomography (CT) scan and Magnetic Resonance imaging (MRI) showed a mass with rough edge and dense calcification in the upper pole of the right kidney and normal left kidney. Pre-operative diagnosis is cystic nephroma or cystic renal mass (Bosniak III type, Bosniak renal cyst classification). GFR was within normal limits for age and no other significant laboratory aberrations were noted. Patient underwent a right retroperitoneal laparoscopic partial nephrectomy (margin status was negative). A mini literature review was performed to highlight the principals of diagnosis and treatment of cystic renal mass with heterotopic ossification. RESULTS:The entire renal mass was successfully removed from upper pole of the right kidney by laparoscopic nephron sparing surgery. The size of renal mass is 38×35×30 mm3 with thick and hard capsular wall. The cystic cavity contains yellow lipid-like substances without stone. Histological examination revealed renal cyst in which the cyst wall reveals fibrosis and no obvious lining epithelium. The additional unique feature includes the presence of dense calcification and ossification in the renal mass. Localization tissue of yellow bone marrow was detected. No complications occurred in 9 months after surgery during follow-up. CONCLUSIONS:Cystic renal mass with heterotopic ossification is a rare case of non-malignant renal tumor. Whether surgery is needed depends to whether patients have symptoms. For symptom renal tumors, laparoscopic nephron sparing surgical procedure is recommended. Furthermore, complete surgical resection of the lesion is needed when the mass is suspected to be malignant. An accurate histologic diagnosis is key in its diagnosis.

中文翻译：

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一例罕见的肾囊性肿块伴异位骨化及小型文献综述

引言：对肾肿瘤进行准确的术前诊断是一项挑战。本研究旨在报告一例罕见的囊性肾肿块骨化病例的发现、处理和结果。我们介绍并讨论患者的病理特征、放射学特征和治疗选择。患者与方法：一名 38 岁的女性患者有两个月的间歇性上腹痛和镜下血尿。计算机断层扫描 (CT) 扫描和磁共振成像 (MRI) 显示右肾上极和正常左肾有一个边缘粗糙和致密钙化的肿块。术前诊断为囊性肾瘤或囊性肾肿块（Bosniak III 型，Bosniak 肾囊肿分类）。GFR 在年龄的正常范围内，没有发现其他显着的实验室畸变。患者接受了右侧腹膜后腹腔镜肾部分切除术（切缘状态为阴性）。进行了一项小型文献综述，以强调异位骨化的囊性肾肿块的诊断和治疗原则。结果：腹腔镜保留肾单位手术成功切除了右肾上极的整个肾脏肿块。肾脏肿块大小为38×35×30 mm3，包膜壁厚而硬。囊腔内含黄色脂质样物质，无结石。组织学检查显示肾囊肿，囊壁显示纤维化，无明显衬里上皮。额外的独特特征包括肾肿块中存在致密的钙化和骨化。检测到黄色骨髓的定位组织。术后随访9个月无并发症发生。结论：肾囊性肿块伴异位骨化是一种罕见的非恶性肾肿瘤。是否需要手术取决于患者是否有症状。对于有症状的肾肿瘤，建议进行腹腔镜保留肾单位手术。此外，当怀疑肿块是恶性时，需要对病变进行完整的手术切除。准确的组织学诊断是其诊断的关键。当怀疑肿块为恶性时，需要对病变进行完整的手术切除。准确的组织学诊断是其诊断的关键。当怀疑肿块为恶性时，需要对病变进行完整的手术切除。准确的组织学诊断是其诊断的关键。