Patients may be ashamed or actively attempt to disguise their symptoms. This can make diagnosis difficult as symptoms are not always immediately obvious, or have been deliberately hidden to avoid disclosure. If the patient admits to hair pulling, diagnosis is not difficult; if patients deny hair pulling, a differential diagnosis must be pursued. The differential diagnosis will include evaluation for alopecia areata, iron deficiency, hypothyroidism, tinea capitis, traction alopecia, alopecia mucinosa, thallium poisoning, and loose anagen syndrome. In<unk> , a hair pull test is negative. A biopsy can be performed and may be helpful; it reveals traumatized hair follicles with perifollicular hemorrhage, fragmented hair in the dermis, empty follicles, and deformed hair shafts. Multiple catagen hairs are typically seen. An alternative technique to biopsy, particularly for children, is to shave a part of the involved area and observe for regrowth of normal hairs. Classification<unk>  is defined as a self-induced and recurrent loss of hair. It includes the criterion of an increasing sense of tension before pulling the hair and gratification or relief when pulling the hair. However, some people with<unk>  do not endorse the inclusion of "rising tension and subsequent pleasure, gratification, or relief" as part of the criteria because many individuals with<unk>  may not realize they are pulling their hair, and patients presenting for diagnosis may deny the criteria for tension prior to hair pulling or a sense of gratification after hair is pulled.<unk>  may lie on the obsessive-compulsive spectrum, also encompassing obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), nail biting (onychophagia) and skin picking (dermatillomania), tic disorders and eating disorders. These conditions may share clinical features, genetic contributions, and possibly treatment response; however, differences between<unk>  and OCD are present in symptoms, neural function and cognitive profile. In the sense that it is associated with irresistible urges to perform unwanted repetitive behavior,<unk>  is akin to some of these conditions, and rates of<unk>  among relatives of OCD patients is higher than expected by chance. However, differences between the disorder and OCD have been noted, including: differing peak ages at onset, rates of comorbidity, gender differences, and neural dysfunction and cognitive profile. When it occurs in early childhood, it can be regarded as a distinct clinical entity. Because<unk>  can be present in multiple age groups, it is helpful in terms of prognosis and treatment to approach three distinct subgroups by age: preschool age children, preadolescents to young adults, and adults. In preschool age children,<unk>  is considered benign. For these children, hair-pulling is considered either a means of exploration or something done subconsciously, similar to nail-biting and thumb-sucking, and almost never continues into further ages. The most common age of onset of<unk>  is between ages 9 and 13. In this age range,<unk>  is usually chronic, and continues into adulthood.<unk>  that begins in adulthood most commonly arises from underlying psychiatric causes.<unk>  is often not a focused act, but rather hair pulling occurs in a "trance-like" state; hence,<unk>  is subdivided into "automatic" versus "focused" hair pulling. Children are more often in the automatic, or unconscious, subtype and may not consciously remember pulling their hair. Other individuals may have focused, or conscious, rituals associated with hair pulling, including seeking specific types of hairs to pull, pulling until the hair feels "just right", or pulling in response to a specific sensation. Knowledge of the subtype is helpful in determining treatment strategies.
Trichotillomania
Alopecia areata
Koilonychia
Loose anagen syndrome
Onychotillomania
Trichostasis spinulosa
Tinea imbricata
Necrospermia