L1CAM expression in eosinophilic solid and cystic renal cell carcinoma: clinicopathologic and immunophenotypic insights from a multicenter cohort.

Authors

Selva Kabul, Busra Yaprak Bayrak, Busra Ozbek, Elif Ozsagir, Nazif Alperen Yıldırım, Ece Ozturk, Hamed Jafarzadeh, Burcu Biltekin, Melek Buyukgok, Nuran Sungu, Murat Oktay, Ganime Coban, Kemal Kosemehmetoglu, Andres M Acosta, Liang Cheng, Mahmut Akgul

Published in

Human pathology. Pages 106263. Sep 10, 2026. Epub Sep 10, 2026.

Abstract

Eosinophilic solid and cystic renal cell carcinoma (ESC-RCC) is a recently recognized eosinophilic renal neoplasm characterized by distinctive morphologic, immunophenotypic, and molecular features, including frequent TSC/mTOR pathway alterations. Recently, L1 cell adhesion molecule (L1CAM) has gained increasing recognition as a diagnostically and biologically relevant marker in selected eosinophilic renal neoplasms; however, its expression profile in ESC-RCC has not been systematically investigated. We aimed to evaluate L1CAM expression in a multicenter cohort of ESC-RCCs and correlate the findings with clinicopathologic and immunophenotypic features. A retrospective multicenter cohort of 11 ESC-RCCs was collected. Clinicopathologic and immunophenotypic findings were recorded. Immunohistochemistry for L1CAM was performed on representative whole tissue sections and semi-quantitatively scored based on the percentage of positive tumor cells. The cohort included 9 female and 2 male patients with a median age of 50 years (range, 39-79). L1CAM expression was identified in 7 of 11 tumors (63.6%), including 5 cases with diffuse membranous (3+) staining and 2 cases with intermediate (2+) staining; no tumor showed only focal (1+) expression. All tumors showed the characteristic morphology of ESC-RCC and expressed KRT20, irrespective of L1CAM status. Among tumors evaluated with additional markers, SDHB expression was retained in all 6 tested tumors and GATA3 was negative in all 5 tested tumors. Molecular testing was not performed in this cohort. Follow-up was available for all 11 patients (median, 10 months), with all patients alive without disease at last follow-up. Our findings expand the known immunophenotypic spectrum of ESC-RCC by demonstrating L1CAM expression in a substantial subset of tumors. However, because L1CAM expression is neither sensitive nor specific for ESC-RCC, positive or negative staining does not support or exclude the diagnosis and does not currently justify routine use of L1CAM in the diagnostic evaluation of morphologically suspected ESC-RCC.

PMID:
42722081
Bibliographic data and abstract were imported from PubMed on 11 Sep 2026.

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