diff --git a/rules-tests/CodingStyle/Rector/Enum_/EnumCaseToPascalCaseRector/Fixture/skip_existing_pascal.php.inc b/rules-tests/CodingStyle/Rector/Enum_/EnumCaseToPascalCaseRector/Fixture/skip_existing_pascal.php.inc
new file mode 100644
index 00000000000..075ae7d5801
--- /dev/null
+++ b/rules-tests/CodingStyle/Rector/Enum_/EnumCaseToPascalCaseRector/Fixture/skip_existing_pascal.php.inc
@@ -0,0 +1,11 @@
+<?php
+
+namespace Rector\Tests\CodingStyle\Rector\Enum_\EnumCaseToPascalCaseRector\Fixture;
+
+enum SkipExistingPascal
+{
+    case Pending;
+    case Published;
+    case InReview;
+    case WaitingForApproval;
+}
diff --git a/rules/CodingStyle/Rector/Enum_/EnumCaseToPascalCaseRector.php b/rules/CodingStyle/Rector/Enum_/EnumCaseToPascalCaseRector.php
index 86219b542eb..7d64f768521 100644
--- a/rules/CodingStyle/Rector/Enum_/EnumCaseToPascalCaseRector.php
+++ b/rules/CodingStyle/Rector/Enum_/EnumCaseToPascalCaseRector.php
@@ -187,7 +187,18 @@ private function refactorClassConstFetch(ClassConstFetch $classConstFetch): ?Nod
 
     private function convertToPascalCase(string $name): string
     {
-        $parts = explode('_', strtolower($name));
-        return implode('', array_map(ucfirst(...), $parts));
+        $parts = explode('_', $name);
+        return implode(
+            '',
+            array_map(
+                fn ($part): string =>
+                // If part is all uppercase, convert to ucfirst(strtolower())
+                // If part is already mixed or PascalCase, keep as is except ucfirst
+                ctype_upper((string) $part)
+                    ? ucfirst(strtolower((string) $part))
+                    : ucfirst((string) $part),
+                $parts
+            )
+        );
     }
 }