Fatima Aisha, Russell Daniel H, Epstein Jonathan I
Departments of Pathology.
Urology.
Am J Surg Pathol. 2023 Apr 1;47(4):461-468. doi: 10.1097/PAS.0000000000002008. Epub 2022 Dec 19.
Nested subtype of urothelial carcinoma (NVUC) of the upper urinary tract is rare. While this subtype has an aggressive behavior in the urinary bladder, little is known about this subtype in the renal pelvis and ureter. In addition, due to NVUC's bland morphology and resemblance to von Brunn nests proliferation, which can be florid in the renal pelvis and ureter, establishing a diagnosis of NVUC in these sites can be difficult, especially on small biopsies. Nineteen cases of NVUC of the renal pelvis and the ureter were identified. One was in-house and 18 cases were sent to the genitourinary pathology consult service. Four cases were excluded due to difficulty in obtaining the slides from other institutions. In all, 8/15 (53.33%) cases showed large nested morphology, 4/15 (26.66%) cases showed mixed large and small nested morphology, and only 3/15 (20%) cases showed predominantly small nested morphology. In all cases, the invasive component was pure nested subtype, and tumors were all unifocal. In 8/15 cases, there was the presence of an overlying low-grade papillary urothelial carcinoma. An associated desmoplastic stromal reaction was none/minimal in 12/15 (80%) cases, with a prominent reaction in the remaining 3/15 (20%) cases. Pathologic stages for the resections were pT1 (n=1), pT2 (n=3), pT3 (n=8), and pT4 (n=1). There was only 1 case with a lymph node metastasis at the time of resection who had pT4 disease. Follow-up was available in 10/15 cases, 7/10 cases showed no recurrences or metastases, and the remaining 3/10 cases later developed urothelial carcinoma of the bladder. In 5/15 cases, follow-up could not be obtained. Similar to NVUC in the urinary bladder, NVUC in the upper tract typically lacks an associated desmoplastic reaction and has by definition bland cytology. In contrast to NVUC of the urinary bladder, NVUC in the upper urothelial tract is: (1) more frequently associated with an overlying papillary urothelial carcinoma; (2) more commonly has a large nested pattern; and (3) appears to behave less aggressively.
上尿路尿路上皮癌的巢状亚型（NVUC）较为罕见。虽然该亚型在膀胱中具有侵袭性，但对于肾盂和输尿管中的此亚型却知之甚少。此外，由于NVUC形态温和，且与肾盂和输尿管中可能呈弥漫性的von Brunn巢状增生相似，在这些部位诊断NVUC可能存在困难，尤其是在小活检标本上。共识别出19例肾盂和输尿管NVUC病例。1例为本机构内部病例，18例送至泌尿生殖系统病理会诊服务处。因难以从其他机构获取切片，排除4例。总体而言，15例中有8例（53.33%）表现为大巢状形态，4例（26.66%）表现为大巢状和小巢状混合形态，仅3例（20%）主要表现为小巢状形态。所有病例中，浸润成分均为单纯巢状亚型，肿瘤均为单灶性。15例中有8例存在上覆的低级别乳头状尿路上皮癌。15例中有12例（80%）伴有促纤维增生性间质反应不明显/轻微，其余3例（20%）反应明显。切除标本的病理分期为pT1（n = 1）、pT2（n = 3）、pT3（n = 8）和pT4（n = 1）。切除时只有1例伴有淋巴结转移，其病理分期为pT4。15例中有10例可进行随访，10例中有7例无复发或转移，其余3例后来发生了膀胱癌。15例中有5例无法获得随访信息。与膀胱NVUC相似，上尿路NVUC通常缺乏相关的促纤维增生性反应，且根据定义，其细胞学表现温和。与膀胱NVUC不同的是，上尿路尿路上皮癌的NVUC：（1）更常与上覆的乳头状尿路上皮癌相关；（2）更常见大巢状模式；（3）侵袭性似乎较小。
