using System;

using System.Collections.Concurrent;

using System.Reflection;

public static class Program

{

    public static void Main()

    {

        var dictionary = new ConcurrentDictionary<int, int>();

        dictionary.TryAdd(1, 10);

        bool removeResult = dictionary.TryRemove(1, out int value, 10);

        Console.WriteLine($"Removed: {removeResult}, Value: {value}");

    }

​

    public static bool TryRemove<TKey, TValue>(

        this ConcurrentDictionary<TKey, TValue> dictionary, TKey key, out TValue value,

        TValue comparand)

    {

        MethodInfo mi = dictionary.GetType().GetMethod("TryRemoveInternal",

            BindingFlags.NonPublic | BindingFlags.Instance);

        object[] args = new object[] { key, default(TValue), true, comparand };

        var result = mi.Invoke(dictionary, args);

        value = (TValue)args[1];

        return (bool)result;

    }

}

​