Distinguish between different skin diseases based on the areas of the body affected; physical appearance of skin bumps and lesions; and the types of factors that trigger or exacerbate flare-ups, according to Mario Badescu Skin Care. For example, fluid-filled bumps occur in eczema but not psoriasis, although both are similar conditions.
Another distinguishing difference between psoriasis and eczema is that psoriasis is often a genetically linked disease, while eczema is related more to environmental factors, explains Mario Badescu Skin Care. As a result, flare-ups in patients with psoriasis are more likely to be related to internal health conditions, such as diabetes. Flare-ups of eczema tend to occur in response to external factors, such as food allergies or contact with certain cleaning chemicals. Another telltale sign is that psoriasis tends to occur on areas of tougher skin, such as the skin on the backs of the elbows, but eczema is most common on areas of sensitive skin, such as the insides of the elbows.
Couperose skin and rosacea are another example of similar skin conditions, notes Mario Badescu Skin Care. Looking for signs of inflammation can help distinguish between the two, as skin affected by rosacea is characterized by excessive inflammation, while couperose skin is not. Patients with rosacea may also feel a burning sensation that couperose skin does not typically produce.