Amer Samir M, Mollaee Mehri, Pei Jianming, Patchefsky Arthur S, Kutikov Alexander, Uzzo Robert G, Wei Shuanzeng
Department of Pathology, Temple University Hospital, Philadelphia, PA, USA.
Department of Pathology, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
Hum Pathol. 2025 May;159:105817. doi: 10.1016/j.humpath.2025.105817. Epub 2025 May 26.
As its descriptive name indicates, mucinous tubular and spindle cell carcinoma (MTSCC) is composed of tubules, spindle cells, and extracellular mucinous stroma. Papillary architecture in MTSCC is regarded as infrequent finding and often is described as papillation or pseudopapillary appearance since bona fide papillary structures with fibrovascular cores are not seen. In this study, we report five cases of MTSCC with papillary formation and compare those with 18 cases of former type 1 papillary renal cell carcinoma (PRCC). Chromosomal microarray analysis was performed to confirm the diagnosis. All 5 MTSCC tumors exhibited at least focal papillary formation. However, the fibrovascular cores were generally mucinous with scant cellularity and vessels. In addition, psammoma bodies were observed in two, and foamy macrophages were seen in four cases of MTSCC. All PRCC cases exhibited classical papillary architecture without bland spindled tumor cells. Interestingly, focal mucinous stroma was observed in 7 PRCC (39 %). Foamy macrophages were identified in 15 (83 %), and psammoma bodies in 5 PRCC cases (28 %). The MTSCC had the typical monosomy of multiple chromosomes. However, the trisomy of 7, 17, and loss of Y typically found in PRCC were not observed in any of the 5 MTSCC. In summary, MTSCC and PRCC share many morphological features, including papillary formation, foamy macrophages, psammoma bodies, and mucinous stroma which should be emphasized. These shared features make distinguishing MTSCC from PRCC difficult in a small core biopsy or fine needle aspiration (FNA) specimen. Chromosomal microarray or FISH can be helpful in problematic cases.
正如其描述性名称所示，黏液性肾小管和梭形细胞癌（MTSCC）由小管、梭形细胞和细胞外黏液性间质组成。MTSCC中的乳头结构被认为是罕见的发现，并且由于未见具有纤维血管轴心的真正乳头结构，常被描述为乳头样或假乳头外观。在本研究中，我们报告了5例具有乳头形成的MTSCC病例，并将其与18例以前的1型乳头状肾细胞癌（PRCC）进行比较。进行染色体微阵列分析以确诊。所有5例MTSCC肿瘤均至少表现为局灶性乳头形成。然而，纤维血管轴心通常为黏液性，细胞和血管稀少。此外，在2例MTSCC中观察到砂粒体，4例中可见泡沫状巨噬细胞。所有PRCC病例均表现为典型的乳头结构，无平淡的梭形肿瘤细胞。有趣的是，7例PRCC（39%）中观察到局灶性黏液性间质。15例（83%）中发现泡沫状巨噬细胞，5例PRCC病例（28%）中发现砂粒体。MTSCC具有典型的多条染色体单体性。然而，在5例MTSCC中均未观察到PRCC中典型的7、17三体及Y染色体缺失。总之，MTSCC和PRCC具有许多形态学特征相同，包括乳头形成、泡沫状巨噬细胞、砂粒体和黏液性间质，这一点应予以强调。这些共同特征使得在小的芯针活检或细针穿刺（FNA）标本中区分MTSCC和PRCC很困难。染色体微阵列或FISH在疑难病例中可能会有帮助。
