diff --git a/lms/djangoapps/discussion_api/api.py b/lms/djangoapps/discussion_api/api.py
index 0141a3a977..6d11d47d0c 100644
--- a/lms/djangoapps/discussion_api/api.py
+++ b/lms/djangoapps/discussion_api/api.py
@@ -375,7 +375,9 @@ def _get_users(discussion_entity_type, discussion_entity, username_profile_dict)
 
         A dict of users with username as key and user profile details as value.
     """
-    users = {discussion_entity['author']: _user_profile(username_profile_dict[discussion_entity['author']])}
+    users = {}
+    if discussion_entity['author']:
+        users[discussion_entity['author']] = _user_profile(username_profile_dict[discussion_entity['author']])
 
     if discussion_entity_type == DiscussionEntity.comment and discussion_entity['endorsed']:
         users[discussion_entity['endorsed_by']] = _user_profile(username_profile_dict[discussion_entity['endorsed_by']])
@@ -446,7 +448,7 @@ def _serialize_discussion_entities(request, context, discussion_entities, reques
         results.append(serialized_entity)
 
         if include_profile_image:
-            if serialized_entity['author'] not in usernames:
+            if serialized_entity['author'] and serialized_entity['author'] not in usernames:
                 usernames.append(serialized_entity['author'])
             if (
                     'endorsed' in serialized_entity and serialized_entity['endorsed'] and
diff --git a/lms/djangoapps/discussion_api/tests/test_views.py b/lms/djangoapps/discussion_api/tests/test_views.py
index acc1794ff4..4b25ae364a 100644
--- a/lms/djangoapps/discussion_api/tests/test_views.py
+++ b/lms/djangoapps/discussion_api/tests/test_views.py
@@ -354,6 +354,28 @@ class ThreadViewSetListTest(DiscussionAPIViewTestMixin, ModuleStoreTestCase, Pro
         thread.update(overrides or {})
         return thread
 
+    def create_source_thread(self, overrides=None):
+        """
+        Create a sample source cs_thread
+        """
+        thread = make_minimal_cs_thread({
+            "id": "test_thread",
+            "course_id": unicode(self.course.id),
+            "commentable_id": "test_topic",
+            "user_id": str(self.user.id),
+            "username": self.user.username,
+            "created_at": "2015-04-28T00:00:00Z",
+            "updated_at": "2015-04-28T11:11:11Z",
+            "title": "Test Title",
+            "body": "Test body",
+            "votes": {"up_count": 4},
+            "comments_count": 5,
+            "unread_comments_count": 3,
+        })
+
+        thread.update(overrides or {})
+        return thread
+
     def test_course_id_missing(self):
         response = self.client.get(self.url)
         self.assert_response_correct(
@@ -372,20 +394,9 @@ class ThreadViewSetListTest(DiscussionAPIViewTestMixin, ModuleStoreTestCase, Pro
 
     def test_basic(self):
         self.register_get_user_response(self.user, upvoted_ids=["test_thread"])
-        source_threads = [make_minimal_cs_thread({
-            "id": "test_thread",
-            "course_id": unicode(self.course.id),
-            "commentable_id": "test_topic",
-            "user_id": str(self.author.id),
-            "username": self.author.username,
-            "created_at": "2015-04-28T00:00:00Z",
-            "updated_at": "2015-04-28T11:11:11Z",
-            "title": "Test Title",
-            "body": "Test body",
-            "votes": {"up_count": 4},
-            "comments_count": 5,
-            "unread_comments_count": 3,
-        })]
+        source_threads = [
+            self.create_source_thread({"user_id": str(self.author.id), "username": self.author.username})
+        ]
         expected_threads = [self.make_expected_thread({
             "created_at": "2015-04-28T00:00:00Z",
             "updated_at": "2015-04-28T11:11:11Z",
@@ -640,54 +651,8 @@ class ThreadViewSetListTest(DiscussionAPIViewTestMixin, ModuleStoreTestCase, Pro
         user_2.profile.year_of_birth = 1970
         user_2.profile.save()
         source_threads = [
-            {
-                "type": "thread",
-                "id": "test_thread",
-                "course_id": unicode(self.course.id),
-                "commentable_id": "test_topic",
-                "group_id": None,
-                "user_id": str(self.user.id),
-                "username": self.user.username,
-                "anonymous": False,
-                "anonymous_to_peers": False,
-                "created_at": "2015-04-28T00:00:00Z",
-                "updated_at": "2015-04-28T11:11:11Z",
-                "thread_type": "discussion",
-                "title": "Test Title",
-                "body": "Test body",
-                "pinned": False,
-                "closed": False,
-                "abuse_flaggers": [],
-                "votes": {"up_count": 4},
-                "comments_count": 5,
-                "unread_comments_count": 3,
-                "read": False,
-                "endorsed": False
-            },
-            {
-                "type": "thread",
-                "id": "test_thread",
-                "course_id": unicode(self.course.id),
-                "commentable_id": "test_topic",
-                "group_id": None,
-                "user_id": str(user_2.id),
-                "username": user_2.username,
-                "anonymous": False,
-                "anonymous_to_peers": False,
-                "created_at": "2015-04-28T00:00:00Z",
-                "updated_at": "2015-04-28T11:11:11Z",
-                "thread_type": "discussion",
-                "title": "Test Title",
-                "body": "Test body",
-                "pinned": False,
-                "closed": False,
-                "abuse_flaggers": [],
-                "votes": {"up_count": 4},
-                "comments_count": 5,
-                "unread_comments_count": 3,
-                "read": False,
-                "endorsed": False
-            }
+            self.create_source_thread(),
+            self.create_source_thread({"user_id": str(user_2.id), "username": user_2.username}),
         ]
 
         self.register_get_user_response(self.user, upvoted_ids=["test_thread"])
@@ -707,6 +672,28 @@ class ThreadViewSetListTest(DiscussionAPIViewTestMixin, ModuleStoreTestCase, Pro
             response_users = response_thread['users']
             self.assertEqual(expected_profile_data, response_users[response_thread['author']])
 
+    def test_profile_image_requested_field_anonymous_user(self):
+        """
+        Tests profile_image in requested_fields for thread created with anonymous user
+        """
+        source_threads = [
+            self.create_source_thread(
+                {"user_id": None, "username": None, "anonymous": True, "anonymous_to_peers": True}
+            ),
+        ]
+
+        self.register_get_user_response(self.user, upvoted_ids=["test_thread"])
+        self.register_get_threads_response(source_threads, page=1, num_pages=1)
+
+        response = self.client.get(
+            self.url,
+            {"course_id": unicode(self.course.id), "requested_fields": "profile_image"},
+        )
+        self.assertEqual(response.status_code, 200)
+        response_thread = json.loads(response.content)['results'][0]
+        self.assertIsNone(response_thread['author'])
+        self.assertEqual({}, response_thread['users'])
+
 
 @httpretty.activate
 @disable_signal(api, 'thread_created')