diff --git a/cpp/src/arrow/dataset/file_parquet.cc b/cpp/src/arrow/dataset/file_parquet.cc
index 8d019924b8a82..ca391b4354c07 100644
--- a/cpp/src/arrow/dataset/file_parquet.cc
+++ b/cpp/src/arrow/dataset/file_parquet.cc
@@ -369,11 +369,9 @@ std::optional<compute::Expression> ParquetFileFragment::EvaluateStatisticsAsExpr
   bool may_have_null = !statistics.HasNullCount() || statistics.null_count() > 0;
   // Optimize for corner case where all values are nulls
   if (statistics.num_values() == 0) {
-    // If `statistics.HasNullCount()`, it means the all the values are nulls.
-    //
-    // If there are no values and `!statistics.HasNullCount()`, it might be
-    // empty or all values are nulls. In this case, we also return a null
-    // expression.
+    // If there are no non-null values, column `field_ref` in the fragment
+    // might be empty or all values are nulls. In this case, we also return
+    // a null expression.
     return is_null(std::move(field_expr));
   }