Contributor: Gordon K. Klintworth
Dermatitis is a heterogenous common skin disease that affects many parts of the skin including the eyelids. The types of dermatitis can be divided into those with a specific causal agent and those with a specific distribution in the skin. Causes of dermatitis include radiation ([dermatitis - actinic, dermatitis - radiation]), hypersensitivity reactions ( [dermatitis - allergic, dermatitis - contact, dermatitis - rhus, dermatitis medicamentosa, dermatitis - nickel, dermatitis - dhobie mark], organisms ( [dermatitis - brown-tail moth, dermatitis - caterpillar, dermatitis - insect], infectious dermatitis [dermatitis - infectious](dermatitis herpetiformis,  dermatitis - chigger], mites [dermatitis - onion mite, dermatitis - rat-mite, scabies], nematodes [dermatitis - uncinarial, dermatitis - verminous], cercarial dermatitis [dermatitis - cercarial]), moth dermatitis [dermatitis - moth],  and viruses (viral papular dermatitis [dermatitis - viral papular]). Some types of dermatitis are idiopathic ([dermatitis - ashy, dermatitis - berlock,  dermatitis - perioral, dermatitis - periocular], dermatitis bullosa striata pratensis (dermatitis stiata pratensis bullosa)[dermatitis - bullosa striata pratensis], exposure to abnormal temperatures (dermatitis calorica), cosmetic dermatitis [dermatitis - cosmetic], diaper dermatitis [dermatitis - diaper],  dermatitis exfoliativa, dermatitis exfoliativa neonatorum, exfoliative dermatitis [dermatitis - exfoliative],  eczematous dermatitis [dermatitis - eczematous], self-inflicted injury [dermatitis - factial], dermatitis gangenosa infantum, gangrenous dermatitis [dermatitis - gangrenous], dermatitis hiemalis, industrial dermatitis  [dermatitis - industrial],  irritant dermatitis [dermatitis - irritant], ischemia (livedoid dermatitis [dermatitis - livedoid]), marine dermatitis [dermatitis - marine], allergic reaction to grass (meadow dermatitis [dermatitis - meadow]), nummular eczematous dermatitis [dermatitis - nummular eczematous], dermatitis papillaris capillitii, pelodera dermatitis [dermatitis - pelodera],  photoallergic dermatitis [dermatitis - photoallergic], phototoxic dermatitis [dermatitis - phototoxic], phytotoxic dermatitis [dermatitis - phytotoxic], pigmented purpuric lichenoid dermatitis [dermatitis - pigmented purpuric lichenoid ], precancerous dermatitis [dermatitis - precancerous],  dermatitis repens, sabra dermatitis [dermatitis - sabra], seborrheic dermatitis [dermatitis - seborrheic], stasis dermatitis [dermatitis - allergic], dermatitis vegetans, verrucose dermatitis [dermatitis - verrucose], vesicular dermatitis [dermatitis - vesicular]. Some varieties of dermatitis, such as perioral dermatitis and periocular dermatitis, affect specific parts of the skin.