ALK-rearranged renal cell carcinoma with a novel PLEKHA7-ALK translocation and metanephric adenoma-like morphology
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BRIEF REPORT
ALK-rearranged renal cell carcinoma with a novel PLEKHA7-ALK translocation and metanephric adenoma-like morphology Jen-Fan Hang 1,2
&
Hsiao-Jen Chung 3,4 & Chin-Chen Pan 1,2
Received: 24 December 2019 / Revised: 6 January 2020 / Accepted: 9 January 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract ALK-rearranged renal cell carcinoma is a provisional entity in the 2016 WHO Classification of Tumors of the Urinary System and Male Genital Organs. The reported fusion partners included VCL, TPM3, EML4, STRN, and HOOK1. Herein, we present a peculiar renal cell carcinoma morphologically resembling metanephric adenoma and harboring a novel PLEKHA7-ALK fusion. Microscopically, the tumor is composed of bland epithelial cells with scant to moderate amount of amphophilic cytoplasm, round and uniform nuclei, delicate chromatin, and inconspicuous nucleoli, arranged in tightly packed small acini and angulated tubules. Papillary formation, intraluminal glomeruloid tufts, microcysts, and solid nests were focally observed. Psammomatous calcifications were evident. The tumor cells were diffusely reactive for CK7, AMACR, PAX8, and ALK, while non-reactive for WT1, BRAF V600E, CD57, carbonic anhydrase IX, TFE3, and cathepsin K. Fluorescence in situ hybridization showed breaking apart of ALK. A novel PLEKHA7exon18-ALKexon20 fusion was detected using ArcherDX FusionPlex next-generation sequencing panel and was further confirmed with reversetranscriptase PCR. Our case demonstrates that in contrast to prior cases showing high-grade tumor cells, ALK-rearranged renal cell carcinoma may also present as a low-grade renal tumor mimicking metanephric adenoma. Immunohistochemistry and molecular testing are helpful to identify this tumor, which may be eligible for ALK inhibitor-targeted therapy. Keywords PLEKHA7 . ALK . Renal cell carcinoma . Metanephric adenoma
Introduction ALK-rearranged renal cell carcinoma (RCC) was first reported almost simultaneously by Debelenko et al. [1] and MariñoEnríquez et al. [2] in two black boys with sickle cell trait in 2011. The two tumors were morphologically similar to renal medullary carcinoma and harbored a t(2;10)(p23;q22) * Chin-Chen Pan [email protected] 1
Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, No. 201, Section 2, Shipai Road, Taipei 11217, Taiwan
2
Department of Pathology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
3
Department of Urology, Taipei Veterans General Hospital, Taipei, Taiwan
4
Department of Urology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
translocation, resulting in a VCLexon16-ALKexon20 fusion. Later, ALK-rearranged RCCs with other non-VCL fusion partners (e.g., TPM3 and EML4) were also found in adult patients without sickle cell trait [3–5]. Unlike the VCL-ALK fusionrelated tumors, these tumors mostly presented with papillary architecture and consisted of cuboidal to polygonal cells with eosinophilic to clear cytoplasm. The 2012 International Societ
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