NF2/Merlin Immunohistochemistry Helps Distinguish Collecting Duct Carcinoma From Upper Tract Urothelial…

Cohort studyThe American journal of surgical pathology· Jun 2026

NF2/Merlin Immunohistochemistry Helps Distinguish Collecting Duct Carcinoma From Upper Tract Urothelial Carcinoma.

Ezra Baraban, Doreen N Palsgrove, Cansu Yol … Pedram Argani

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Genitourinary PathologyCohort studyDiagnosisQ1IF 4.3

NF2/Merlin loss by immunohistochemistry is highly specific for collecting duct carcinoma vs upper tract urothelial carcinoma.

NF2/Merlin Immunohistochemistry Helps Distinguish Collecting Duct Carcinoma From Upper Tract Urothelial Carcinoma.

Ezra Baraban … Pedram Argani

The American journal of surgical pathology · Jun 2026 · Q1 in Pathology

Background

Collecting duct carcinoma (collecting duct carcinoma) and upper tract urothelial carcinoma (upper tract urothelial carcinoma) can exhibit overlapping morphologic features, particularly in limited biopsies, creating diagnostic challenges with significant therapeutic implications.

Methods

We evaluated the utility of NF2/Merlin immunohistochemistry (immunohistochemistry) as a diagnostic tool in this differential diagnosis.

n = 16 cases

Results

NF2/Merlin loss strongly favors collecting duct carcinoma over upper tract urothelial carcinoma

CDC

63%

UTUC

0%

More results

Recent molecular studies have identified recurrent NF2 alterations in collecting duct carcinoma, whereas pathogenic NF2 alterations are uncommon in upper tract urothelial carcinoma.

Among 13 collecting duct carcinoma cases with available molecular data, 6 harbored NF2 mutations.

More results

Of these, 6/6 showed NF2/Merlin protein loss by immunohistochemistry, while among 7 collecting duct carcinoma cases lacking NF2 genetic alterations, 5 retained NF2/Merlin expression and 2 showed protein loss by immunohistochemistry.

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Conclusion

This marker represents a useful addition to the immunohistochemical panel for evaluating infiltrative renal carcinomas with tubular architecture, offering objective support for the diagnosis of collecting duct carcinoma in the appropriate morphologic and immunohistochemical context.

NF2/Merlin Immunohistochemistry Helps Distinguish Collecting Duct Carcinoma From Upper Tract Urothelial Carcinoma.

NF2/Merlin Immunohistochemistry Helps Distinguish Collecting Duct Carcinoma From Upper Tract Urothelial Carcinoma.

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