diff --git a/litellm/llms/anthropic/pass_through/adapters/transformation.py b/litellm/llms/anthropic/pass_through/adapters/transformation.py
index 0d3e48c49fd..019fd6db1c5 100644
--- a/litellm/llms/anthropic/pass_through/adapters/transformation.py
+++ b/litellm/llms/anthropic/pass_through/adapters/transformation.py
@@ -520,8 +520,25 @@ class LiteLLMAnthropicMessagesAdapter:
                                     self._add_prompt_cache_breakpoint_if_present(content, image_obj)
                                 )
                         elif content.get("type") == "document":
-                            # Convert Anthropic document format (PDF, etc.) to OpenAI format
+                            # Convert Anthropic document format to OpenAI format.
+                            # Only image/* media types can be forwarded as image_url;
+                            # non-image documents (e.g. application/pdf) are not
+                            # accepted by image-only backends and must be rejected
+                            # with a clear error rather than silently producing a
+                            # malformed request.
                             source = content.get("source", {})
+                            media_type = source.get("media_type", "") if isinstance(source, dict) else ""
+                            if media_type and not str(media_type).startswith("image/"):
+                                raise litellm.BadRequestError(
+                                    message=(
+                                        f"Document content block with media_type='{media_type}' cannot be "
+                                        "forwarded to this model as an image_url. Only image/* documents "
+                                        "are supported. For PDF documents, convert the pages to images "
+                                        "before sending."
+                                    ),
+                                    model=model,
+                                    llm_provider="anthropic",
+                                )
                             openai_image_url = self._translate_anthropic_image_to_openai(cast(dict, source))
 
                             if openai_image_url:
diff --git a/tests/unit/llms/anthropic/pass_through/adapters/test_anthropic_experimental_pass_through_adapters_transformation.py b/tests/unit/llms/anthropic/pass_through/adapters/test_anthropic_experimental_pass_through_adapters_transformation.py
index 9e0bd5c60b8..17e219da10e 100644
--- a/tests/unit/llms/anthropic/pass_through/adapters/test_anthropic_experimental_pass_through_adapters_transformation.py
+++ b/tests/unit/llms/anthropic/pass_through/adapters/test_anthropic_experimental_pass_through_adapters_transformation.py
@@ -5235,3 +5235,77 @@ def test_eager_input_streaming_tool_reaches_bedrock_converse_as_beta():
 
     assert data["additionalModelRequestFields"]["anthropic_beta"] == ["fine-grained-tool-streaming-2025-05-14"]
     assert data["toolConfig"]["tools"][0]["toolSpec"]["inputSchema"]["json"] == EAGER_INPUT_SCHEMA
+
+
+def test_document_pdf_raises_bad_request_error() -> None:
+    """
+    Regression test for https://github.com/BerriAI/litellm/issues/46117
+
+    An Anthropic document block with media_type='application/pdf' must raise
+    BadRequestError when translated to OpenAI format, not silently produce a
+    malformed image_url with a PDF MIME type that the downstream backend rejects.
+    """
+    adapter = LiteLLMAnthropicMessagesAdapter()
+
+    messages = [
+        AnthropicMessagesUserMessageParam(
+            role="user",
+            content=[
+                {
+                    "type": "document",
+                    "source": {
+                        "type": "base64",
+                        "media_type": "application/pdf",
+                        "data": "JVBERi0xLjQK",  # minimal synthetic PDF header
+                    },
+                },
+                {"type": "text", "text": "Summarize this document."},
+            ],
+        )
+    ]
+
+    with pytest.raises(litellm.BadRequestError) as exc_info:
+        adapter.translate_anthropic_messages_to_openai(
+            messages=messages,
+            model="chatgpt/gpt-6.1-sol",
+        )
+
+    assert "application/pdf" in str(exc_info.value)
+
+
+def test_document_image_jpeg_passes_through() -> None:
+    """
+    An Anthropic document block with media_type='image/jpeg' must still be
+    translated to image_url without raising an error.
+    """
+    adapter = LiteLLMAnthropicMessagesAdapter()
+
+    messages = [
+        AnthropicMessagesUserMessageParam(
+            role="user",
+            content=[
+                {
+                    "type": "document",
+                    "source": {
+                        "type": "base64",
+                        "media_type": "image/jpeg",
+                        "data": "/9j/4AAQSkZJRgAB",  # minimal JPEG header
+                    },
+                },
+                {"type": "text", "text": "Describe this image."},
+            ],
+        )
+    ]
+
+    # Should not raise
+    result = adapter.translate_anthropic_messages_to_openai(
+        messages=messages,
+        model="chatgpt/gpt-6.1-sol",
+    )
+    # The image document should be translated to an image_url content block
+    user_msg = next(m for m in result if m.get("role") == "user")
+    content = user_msg.get("content", [])
+    image_blocks = [c for c in content if isinstance(c, dict) and c.get("type") == "image_url"]
+    assert len(image_blocks) == 1
+    url = image_blocks[0]["image_url"]["url"]
+    assert url.startswith("data:image/jpeg;base64,")