Excoriations and ulcers on the arms and legs

DIFFERENTIAL DIAGNOSIS: PSYCHODERMATOLOGIC DISORDER

The patient’s history and physical examination points to a psychodermatologic disorder. Psycho-dermatologic disorders are conditions involving an interaction between the mind and skin and are classified as:³

• Psychophysiologic disorders:skin disorders worsened by emotional stress
• Primary psychiatric disorders:usually caused by psychological conditions with self-induced skin damage
• Secondary psychiatric disorders: psychological problems developed as a consequence of a disfiguring skin disorder, which negatively effects self-esteem and body image.³

This patient’s excoriations and ulcers are due to self-mutilation. The differential diagnosis includes psychogenic parasitosis, factitial dermatitis, and neurotic excoriations. These 3 skin conditions are primary psychiatric symptoms, and proper diagnosis revolves around being able to assess the dermatologic features and associated psychological disorder.²

Psychogenic parasitosis

Also known as delusional parasitosis, psychogenic parasitosis is a psychodermatologic disorder in which patients believe they are infested with parasites. Patients with this disorder report seeing or feeling parasites on their skin, and they damage their skin in an attempt to remove them. Patients create excoriations and ulcers on easily reached areas, usually the ears, eyes, nose, and extremities. They often present with what is termed the “matchbox sign,” in which they bring containers filled with “small bits of excoriated skin, dried blood, debris, or insect parts as proof of infestation.”²

Women over the age of 50 years are more often affected with psychogenic parasitosis, and the disorder is associated with anxiety, depression, and hypochondriasis.

Factitial dermatitis

Factitial dermatitis, also known as dermatitis artefacta, is a psychodermatologic disorder in which patients damage their skin but deny their self-involvement. This disorder encompasses a wide range of lesions, including blisters, cuts, ulcers, and burns. Patients often are unable to describe how the lesions evolved. Lesions exhibit bizarre patterns not characteristic of any disease.

Young adults and adolescents are more commonly affected, and it is 4 times more common among women than men. Psychological disorders involved with factitial dermatitis include personality disorders and posttraumatic stress disorder.²