diff --git a/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py b/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py
index 3587aa8042f..aaf357effa6 100644
--- a/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py
+++ b/litellm/llms/bedrock/messages/invoke_transformations/anthropic_claude3_transformation.py
@@ -605,11 +605,15 @@ class AmazonAnthropicClaudeMessagesConfig(
                     anthropic_messages_request["system"] = system_messages_to_add
                 elif isinstance(existing_system, str):
                     if existing_system:
-                        anthropic_messages_request["system"] = [{"type": "text", "text": existing_system}] + system_messages_to_add
+                        anthropic_messages_request["system"] = [
+                            {"type": "text", "text": existing_system}
+                        ] + system_messages_to_add
                     else:
                         anthropic_messages_request["system"] = system_messages_to_add
                 elif isinstance(existing_system, list):
-                    anthropic_messages_request["system"] = list(existing_system) + system_messages_to_add
+                    anthropic_messages_request["system"] = (
+                        list(existing_system) + system_messages_to_add
+                    )
 
     def transform_anthropic_messages_request(
         self,
diff --git a/tests/pass_through_unit_tests/test_bedrock_anthropic_messages_test.py b/tests/pass_through_unit_tests/test_bedrock_anthropic_messages_test.py
index 0ec468b5d8a..4dbf841ca2a 100644
--- a/tests/pass_through_unit_tests/test_bedrock_anthropic_messages_test.py
+++ b/tests/pass_through_unit_tests/test_bedrock_anthropic_messages_test.py
@@ -144,58 +144,58 @@ def test_bedrock_anthropic_messages_system_role_transformation():
     to the top-level system parameter for Bedrock.
     """
     config = litellm.AmazonAnthropicClaudeMessagesConfig()
-    
+
     # 1. Test case: System message in messages array, no existing system param
     req = config.transform_anthropic_messages_request(
         model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
         messages=[
             {"role": "system", "content": "You are a helpful assistant"},
-            {"role": "user", "content": "Hello"}
+            {"role": "user", "content": "Hello"},
         ],
         anthropic_messages_optional_request_params={"max_tokens": 100},
         litellm_params={},
-        headers={}
+        headers={},
     )
-    
+
     assert req["messages"] == [{"role": "user", "content": "Hello"}]
     assert req["system"] == [{"type": "text", "text": "You are a helpful assistant"}]
-    
+
     # 2. Test case: System message in messages array, and existing system param
     req = config.transform_anthropic_messages_request(
         model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
         messages=[
             {"role": "system", "content": "System message in messages array"},
-            {"role": "user", "content": "Hello"}
+            {"role": "user", "content": "Hello"},
         ],
         anthropic_messages_optional_request_params={
             "max_tokens": 100,
-            "system": "Existing top-level system message"
+            "system": "Existing top-level system message",
         },
         litellm_params={},
-        headers={}
+        headers={},
     )
-    
+
     assert req["messages"] == [{"role": "user", "content": "Hello"}]
     assert req["system"] == [
         {"type": "text", "text": "Existing top-level system message"},
-        {"type": "text", "text": "System message in messages array"}
+        {"type": "text", "text": "System message in messages array"},
     ]
-    
+
     # 3. Test case: Empty system message content (should remove system message from messages, system param unaffected)
     req = config.transform_anthropic_messages_request(
         model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
         messages=[
             {"role": "system", "content": ""},
-            {"role": "user", "content": "Hello"}
+            {"role": "user", "content": "Hello"},
         ],
         anthropic_messages_optional_request_params={"max_tokens": 100},
         litellm_params={},
-        headers={}
+        headers={},
     )
-    
+
     assert req["messages"] == [{"role": "user", "content": "Hello"}]
     assert "system" not in req
-    
+
     # 4. Test case: Non-text items in list content (should only extract text items, ignore non-text)
     req = config.transform_anthropic_messages_request(
         model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
@@ -204,16 +204,155 @@ def test_bedrock_anthropic_messages_system_role_transformation():
                 "role": "system",
                 "content": [
                     {"type": "text", "text": "This is text"},
-                    {"type": "image", "source": {"type": "base64", "media_type": "image/jpeg", "data": "abc"}}
-                ]
+                    {
+                        "type": "image",
+                        "source": {
+                            "type": "base64",
+                            "media_type": "image/jpeg",
+                            "data": "abc",
+                        },
+                    },
+                ],
             },
-            {"role": "user", "content": "Hello"}
+            {"role": "user", "content": "Hello"},
         ],
         anthropic_messages_optional_request_params={"max_tokens": 100},
         litellm_params={},
-        headers={}
+        headers={},
     )
-    
+
     assert req["messages"] == [{"role": "user", "content": "Hello"}]
     assert req["system"] == [{"type": "text", "text": "This is text"}]
 
+    # 5. Test case: cache_control in system message (should preserve cache_control)
+    req = config.transform_anthropic_messages_request(
+        model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
+        messages=[
+            {
+                "role": "system",
+                "content": "Cached system message",
+                "cache_control": {"type": "ephemeral"},
+            },
+            {"role": "user", "content": "Hello"},
+        ],
+        anthropic_messages_optional_request_params={"max_tokens": 100},
+        litellm_params={},
+        headers={},
+    )
+    assert req["messages"] == [{"role": "user", "content": "Hello"}]
+    assert req["system"] == [
+        {
+            "type": "text",
+            "text": "Cached system message",
+            "cache_control": {"type": "ephemeral"},
+        }
+    ]
+
+    # 6. Test case: content as list, type text with empty text, cache_control, and list containing non-dict items
+    req = config.transform_anthropic_messages_request(
+        model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
+        messages=[
+            {
+                "role": "system",
+                "content": [
+                    {
+                        "type": "text",
+                        "text": "This is text",
+                        "cache_control": {"type": "ephemeral"},
+                    },
+                    {"type": "text", "text": ""},  # empty text, should be ignored
+                    "invalid_non_dict_item",  # non-dict item in list, should be ignored
+                ],
+            },
+            {"role": "user", "content": "Hello"},
+        ],
+        anthropic_messages_optional_request_params={"max_tokens": 100},
+        litellm_params={},
+        headers={},
+    )
+    assert req["messages"] == [{"role": "user", "content": "Hello"}]
+    assert req["system"] == [
+        {
+            "type": "text",
+            "text": "This is text",
+            "cache_control": {"type": "ephemeral"},
+        }
+    ]
+
+    # 7. Test case: system_messages_found is True but system_messages_to_add is empty (e.g., content list only has non-text item)
+    req = config.transform_anthropic_messages_request(
+        model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
+        messages=[
+            {
+                "role": "system",
+                "content": [
+                    {
+                        "type": "image",
+                        "source": {
+                            "type": "base64",
+                            "media_type": "image/jpeg",
+                            "data": "abc",
+                        },
+                    }
+                ],
+            },
+            {"role": "user", "content": "Hello"},
+        ],
+        anthropic_messages_optional_request_params={"max_tokens": 100},
+        litellm_params={},
+        headers={},
+    )
+    assert req["messages"] == [{"role": "user", "content": "Hello"}]
+    assert "system" not in req
+
+    # 8. Test case: existing_system is empty string
+    req = config.transform_anthropic_messages_request(
+        model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
+        messages=[
+            {"role": "system", "content": "System message"},
+            {"role": "user", "content": "Hello"},
+        ],
+        anthropic_messages_optional_request_params={
+            "max_tokens": 100,
+            "system": "",
+        },
+        litellm_params={},
+        headers={},
+    )
+    assert req["messages"] == [{"role": "user", "content": "Hello"}]
+    assert req["system"] == [{"type": "text", "text": "System message"}]
+
+    # 9. Test case: existing_system is list
+    req = config.transform_anthropic_messages_request(
+        model="bedrock/us.anthropic.claude-sonnet-4-5-20250929-v1:0",
+        messages=[
+            {"role": "system", "content": "System message"},
+            {"role": "user", "content": "Hello"},
+        ],
+        anthropic_messages_optional_request_params={
+            "max_tokens": 100,
+            "system": [{"type": "text", "text": "Existing list item"}],
+        },
+        litellm_params={},
+        headers={},
+    )
+    assert req["messages"] == [{"role": "user", "content": "Hello"}]
+    assert req["system"] == [
+        {"type": "text", "text": "Existing list item"},
+        {"type": "text", "text": "System message"},
+    ]
+
+    # 10. Test case: messages contains elements that are not dicts or do not have role="system"
+    req_data = {
+        "messages": [
+            "not_a_dict_message",
+            {"content": "no_role_key"},
+            {"role": "user", "content": "Hello"},
+        ]
+    }
+    config._extract_system_messages_from_messages(req_data)
+    assert req_data["messages"] == [
+        "not_a_dict_message",
+        {"content": "no_role_key"},
+        {"role": "user", "content": "Hello"},
+    ]