To manage these conditions successfully, it is important to differentiate them from other similar conditions. The most common disorders that need to be differentiated from somatization disorder and undifferentiated somatoform disorder are somatized anxiety, somatized depressive disorders, panic disorder, hypochondriasis, conversion disorder, chronic pain disorders, factitious disorder, and general medical problems.

Somatized Anxiety
Somatized anxiety is a condition that results when psychic anxiety is transformed into muscle tension. The important aspect of this differential diagnosis is that patients with somatized anxiety usually do not have a lifetime history of multiple unexplained somatic symptoms. Instead, they have one or two symptoms that could have begun at any age. Another differential factor is that somatized anxiety usually takes the form of musculoskeletal, sympathetic cardiovascular, or gastrointestinal symptoms. Although patients with somatization disorder and undifferentiated somatoform disorder do have comorbid anxiety, the larger picture is one of multiple unexplained somatic complaints along with the associated anxiety, rather than one of primarily anxiety with a few associated somatic symptoms.

Somatized Depressive Disorders
Patients with major depression or dysthymia may present with somatized symptoms, such as diffuse mild abdominal pain or shoulder or neck aches. However, patients with somatized depression do not have lifelong histories of multiple unexplained somatic complaints. Several somatic complaints may accompany their depression, but their history is primarily one of single or multiple episodes of depression with associated somatic symptoms, rather than one of multiple somatic symptoms with associated dysphoria or blue mood.

Panic Disorder
Panic disorder also must be differentiated from somatization disorder and undifferentiated somatoform disorder. The differential diagnosis relies on the fact that the somatic symptoms associated with panic disorder are expressly attributable to the panic attack and its accompanying intense but short-lived anxiety. In contrast, somatization disorder is a chronic relapsing condition involving multiple symptoms with numerous complaints. Panic disorder patients may have several somatic complaints at the time of their presentation; however, they do not have a history of multiple unexplained somatic problems.

Hypochondriasis
Hypochondriasis is a somatoform disorder that has the essential feature of a preoccupation with the fear of having or the belief that one has a serious disease, based on the person’s interpretation of physical signs and symptoms. In this differential diagnosis, the patient presents with a somatic complaint, but, with minimal inquiry from the clinician, it becomes evident that the patient is anxious about having a disease. Patients with somatization disorder characteristically are not concerned about the underlying disease; instead, they are focused on their symptoms. Although some patients may have both hypochondriasis and somatization disorder, hypochondriacal patients usually do not have the lifelong history of multiple symptoms that somatization or undifferentiated somatoform disorder patients have.

Conversion Disorder
Conversion disorder is a psychiatric disorder characterized by the presence of a conversion symptom (i.e., a loss of function presumably based on intrapsychic conflict). Conversion symptoms are also present as part of the diagnostic picture of patients with somatization disorder and undifferentiated somatoform disorder. If the conversion symptom is a part of somatization disorder or undifferentiated somatoform disorder, conversion disorder is not diagnosed. If the symptom occurs apart from somatization disorder, conversion disorder is diagnosed. Again, a lifelong history of multiple somatic symptoms is the key to a differential diagnosis of somatization disorder or undifferentiated somatoform disorder.

Somatoform Pain Disorder
Somatoform pain disorder is a psychiatric condition characterized by preoccupation with pain in the absence of physical findings to account for the pain or its intensity. Like a conversion symptom, the somatoform pain symptom may be a component of somatization disorder. However, patients with somatization disorder have multiple symptoms, and the diagnosis of somatization disorder or undifferentiated somatoform disorder takes precedence over somatoform pain disorder.

Factitious Disorders
Factitious disorders with physical symptoms have been given various names (e.g., Munchausen syndrome). Patients with factitious disorders make no conscious attempt to be ill for any reason other than to gain the sick role. Malingering individuals make a conscious attempt to manipulate society for some overt gain. Both of these conditions are substantially different from somatization disorder, which, it can be argued, is an unconscious process during which the patient genuinely experiences the symptom and believes that he or she is medically ill.

General Medical Problems
Medical problems also need to be differentiated from somatization disorder and undifferentiated somatoform disorder. General medical problems are usually straightforward, even though initially their presentation may be confusing. Those disorders that require special attention are multiple sclerosis, systemic lupus erythematosus, and hyperparathyroidism. In these situations, the physician must look for signs of these diseases rather than rely on symptoms to differentiate them from somatization disorder. Patients with somatization disorder do not have signs of disease; they only have symptoms.