Any insult that impairs mitosis of hair follicle keratinocytes can cause<unk> . Disruption to cell division in the hair matrix makes the hair narrowed at its base and susceptible to breakage just above the zone of keratinisation. The necrotic matrix forms plugs consisting of melanin, keratin and inner root sheath which are extruded through the follicular opening. This process is known as trichomalacia. The main causes of<unk>  are an infection, a drug, a toxin, radiation or an autoimmune disease. Toxins that can interrupt hair growth include: * Chemotherapy agents, usually prescribed to treat cancer, especially when multiple drugs are used or they are in high dose. Severe hair loss is reported from doxorubicin, the nitrosoureas, and cyclophosphamide. Other causes are bleomycin, dactinomycin, daunorubicin, systemic fluorouracil, and high-dose methotrexate. * Other medicines such as colchicine and ciclosporin (ciclosporin more often causes increased hair growth) * Poisons such as thallium, arsenic, gold and bismuth.
Anagen effluvium
Telogen effluvium
Tinea imbricata
Koilonychia
Linitis plastica
Ichthyosis bullosa of Siemens
Aromaticum rosatum
Xanthelasma