In this hypothetical process, the subjects experience of their leg, for example, is split off from the rest of their consciousness, resulting in paralysis or numbness in that leg. Later authors have attempted to combine elements of these various models, but none of them has a firm empirical basis. In 1908, Steyerthal predicted that: "Within a few years the concept of hysteria will belong to history ... there is no such disease and there never has been. What Charcot called hysteria is a tissue woven of a thousand threads, a cohort of the most varied diseases, with nothing in common but the so-called stigmata, which in fact may accompany any disease." However, the term "hysteria" was still being used well into the 20th century. Some support for the Freudian model comes from findings of high rates of childhood sexual abuse in conversion patients. Support for the dissociation model comes from studies showing heightened suggestibility in conversion patients. However, critics argue that it can be challenging to find organic pathologies for all symptoms, and so the practice of diagnosing patients with such symptoms as having hysteria led to the disorder being meaningless, vague and a sham diagnosis, as it does not refer to any definable disease. Furthermore, throughout its history, many patients have been misdiagnosed with hysteria or conversion disorder when they had organic disorders such as tumours or epilepsy or vascular diseases. This has led to patient deaths, a lack of appropriate care and suffering for the patients.
Melanonychia is a black or brown pigmentation of the normal nail plate, and may be present as a normal finding on many digits in Afro-Caribbeans, as a result of trauma, systemic disease, or medications, or as a postinflammatory event from such localized events as lichen planus or fixed drug eruption. : 790 : 665 There are two types, longitudinal and transverse melanonychia. : 671  Longitudinal melanonychia may be a sign of subungual melanoma (acral lentiginous melanoma), although there are other diagnoses such as chronic paronychia, onychomycosis, subungual hematoma, pyogenic granuloma, glomus tumour, subungual verruca, mucous cyst, subungual fibroma, keratoacanthoma, carcinoma of the nail bed, and subungual exostosis. See also
Nail anatomy
List of cutaneous conditions


== References ==