Elsevier

Human Pathology

Volume 32, Issue 5, May 2001, Pages 506-512
Human Pathology

Original Contributions
Low-grade myxoid renal epithelial neoplasms with distal nephron differentiation

https://doi.org/10.1053/hupa.2001.24320Get rights and content

Abstract

We report 4 distinctive renal epithelial neoplasms that are essentially identical at the morphologic and immunohistochemical levels and do not fit an accepted category in the existing classification of these lesions. The patients were all females, with ages ranging from 32 to 79 years (mean, 50 years). The tumors were well circumscribed and were composed of uniform, predominantly low cuboidal cells with eosinophilic, focally vacuolated cytoplasm. Tumor cells generally formed interconnecting tubules, with smaller areas of cordlike growth and spindling in a bubbly, myxoid stroma. All tumors were confined to the kidney, and all were immunoreactive for high-molecular-weight cytokeratin 34βE12, cytokeratin 7, epithelial membrane antigen, and cytokeratin cocktail AE1/3. Only 1 tumor was focally immunoreactive for Ulex europaeus agglutinin. Ultrastructural study showed tumor cells forming tubular structures reminiscent of the loop of Henle or distal convoluted tubule. Follow-up in all 4 cases was benign. These distinctive tumors may be confused with aggressive sarcomatoid renal cell carcinomas because of their spindled morphology. The morphologic, immunohistochemical, and ultrastructural features of these lesions indicate differentiation toward distal nephron segments. Similar tumors probably have been reported among low-grade collecting duct carcinomas or tumors “possibly related to the loop of Henle.” HUM PATHOL 32:506-512. Copyright © 2001 by W.B. Saunders Company

Section snippets

Case identification and review

The two initial cases in the study were identified in the consultation files of 1 of the authors (J.B.B.). The files of 2 authors (J.B.B., J.I.E.) were then searched electronically for morphologically similar cases using the key words “carcinoma,” “Henle,” and “collecting duct.” Initial review yielded a total group of 6 morphologically similar cases. After immunohistochemical analysis, 2 cases were eliminated because of disparate immunohistochemical labeling patterns (see Discussion), leaving 4

Clinical and gross features

The clinical and gross features of the 4 cases are summarized in Table 2.

. Clinical and Gross Features of the 4 Cases

CaseAge/SexClinical PresentationTumor Diameter/Gross FeaturesPathologic StageClinical Follow-up
141/FAbdominal pain and history of UTI→CT scan2.2 cm/Centered in medulla, yellow-tanpT1NED, 22 mo
248/FAbdominal mass11 cm/Pink-tan, jellylike with hemorrhagepT2NED, 6 yr
379/FAbdominal pain and hematuria→CT scan11 cm/Yellow-tan with necrosis and hemorrhage, located centrally in kidneypT2

Discussion

We report a distinct group of 4 renal neoplasms characterized by noninfiltrative borders, myxoid stroma, elongated tubular and cordlike architecture, and low-grade nuclear features. Their clinical follow-up was benign. The differential diagnosis for these tumors includes both benign and highly malignant entities. One one hand, the low cuboidal shape of the tumor cells, their minimal cytoplasm, low nuclear grade, and interanastamosing tubular pattern raise the differential diagnosis of

Acknowledgements

The authors thank the pathologists who provided cases used for this study: Dr Lawrence Wong (Hollywood, FL), Dr Craig Zuppan (Loma Linda, CA), Dr Karen Axelsson (Oakland, CA), Dr Nancy Newton (Riverdale, GA), Dr Warick Delprado (North Ryde, Australia). They thank Dr Selva Murgesan for performing the immunohistochemical stains and Pete Lund for expert photographic assistance. They gratefully acknowledge Dr Raoul Fresco's expertise in performing the electron microscopic examination and providing

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