Psoriasis
One of the common skin diseases is Psoriasis which is a result of excessive growth of skin cells. As psoriasis is a disease which lasts for many years it is referred to as a chronic skin disease. Though psoriasis is a skin disease like Scabies, there is a major difference. That is, Scabies is not a chronic skin disease and can be classified as an acute skin condition.
Unlike Scabies where the symptoms are pimple-like irritations, burrows or rash of the skin, the usual symptom of psoriasis is the appearance of red patches and silvery scales. The red patches are referred to as “plaques” technically. These plaques are localized in certain areas of the body such as the scalp, face, elbows, knees, palms, and soles of the feet.
Here again it is different from Scabies since Scabies appears as rashes or burrows on the skin and not as scales. Further scabies affects skin folds on the wrist, the webbing between the fingers, whereas as seen earlier psoriasis affects the scalp, face, elbows, knees, palms, and soles of the feet. About 50% of the population who have psoriasis can also notice changes in their finger or toe nails such as the following:
- pitting
- discoloration
- shape changes
- loss of the nail.
Though it is not yet clear as to what causes psoriasis, it is believed that impairment in the working of the immune system can trigger psoriasis. Similarly, it is also believed that bacteria and fungi also could cause psoriasis. Heredity also seems to play a key role in triggering psoriasis. Thus the risk of getting psoriasis through the parents is increased two fold if both the parents have psoriasis. Thus the cause of psoriasis is contrastingly different from Scabies which is caused by the microscopic mite, Sarcoptes scabei.
Unlike Scabies, Psoriasis can be classified into the following five types:
- Psoriasis vulgaris
- Guttate psoriasis
- Pustular psoriasis
- Inverse psoriasis
- Exfoliative psoriasis
Before we go into the details of the above types, we need to know about a painful condition which is caused by psoriasis. It is known as psoriatic arthritis, a disease which affects the joints of the hands and feet, knees, and ankles, which become painful, swollen, hot, red, and stiff and is characterized by inflammation of the joints coupled with the dry scaly and inflamed skin.
It is estimated that about a fourth of the population which has psoriasis is likely to suffer from psoriatic arthritis. Thankfully, Scabies does not have such complications. Psoriasis is also different from scabies in the sense that while in Scabies, there is intense itching, psoriasis is more painful and is devoid of itching. Again, Scabies is an infectious disease while psoriasis is not.
Given below is a Table which highlights the characteristics of the above types.
| Features | Psoriasis Vulgaris | Guttate Psoriasis | Pustular Psoriasis | Inverse Psoriasis | Exfoliative Psoriasis |
| Other names | plaque psoriasis | – | – | skin-fold, flexural, or genital psoriasis | Erythrodermic psoriasis |
| Areas affected | elbows, knees, scalp, chest, nails, and lower back | the upper body, legs, arms, scalp. | Palms, soles | genital area, area under the breasts armpits | entire body |
| Features | presence of raised, red, scaly patches | Makes its appearannce after a throat infection (caused by streptococcus bacteria).
sudden appearance of drop-sized patches in childhood or adolescence |
red and swollen skin, with small, pus-filled pimples or scaly patches. patients may feel ill and run a fever |
characterized by increased sensitivity to friction and sweating. | temperature fluctuations of the body are common. may cause heart failure, since the heart rate may increase due to additional blood flow to area of the inflamed skin. |
| Incidence | 80% to 90% | 10% | rare | common in overweight persons | – |