Infection is also more commonly seen in tropical or sub-tropical climates.Beyond the route of inoculation into the eye and external risk factors, host factors are also likely to play a significant role in the development of Acanthamoeba keratitis. In fact, studies of contact lens users in the United Kingdom, Japan, and New Zealand found that 400 to 800 per 10,000 asymptomatic contact lens users had lens storage cases contaminated with Acanthamoeba spp. However, the rate of Acanthamoeba keratitis among these patients was only 0.01 to 1.49 per 10,000 contact lens users. Although the exact host factors have not been fully described, it is likely that corneal epithelial defects, tear film composition, eye surface pH, and the level of anti-Acanthamoeba IgA antibodies in the tear film play a role in the development of Acanthamoeba keratitis. Life cycle
Species within the genus, Acanthamoeba, are generally free-living trophozoites. These trophozoites are relatively ubiquitous and can live in, but are not restricted to, tap water, freshwater lakes, rivers and soil. In addition to the trophozoite stage, the organism can also form a double-walled cyst which may also be present in the environment, and can be very difficult to eradicate through medical treatment. Both of these stages are usually non-nucleated and reproduce by the means of binary fission. Diagnosis
Due to the relative rarity of Acanthamoeba keratitis (AK) compared to other causes of keratitis (bacterial, viral, etc. ), it is often misdiagnosed, especially in the early stages of the disease.
Fibrofolliculomas are 2 to 4 mm in diameter, dome-shaped, yellowish or skin-colored papules usually located on the head, neck, and upper trunk. They are characteristically seen in Birt–Hogg–Dubé syndrome. : 674

See also
List of cutaneous conditions
List of cutaneous neoplasms associated with systemic syndromes
Trichodiscoma


== References ==