- Heads on discoid plants have an extra whorl of disc florets instead of ray florets.
- A further possibility is discoid lupus erythematosus, the technical term for an autoimmune dermatitis of dogs that is usually confined to the face and is frequently made worse by exposure to ultraviolet light.
- It has been reported that 20 percent of patients with systemic lupus erythematosus will develop discoid skin lesions; however, most patients who have only cutaneous lupus at presentation will not progress to systemic disease.
- Platelet activation is observed as a morphological change from the resting discoid state to activated spherical cells with pseudopods.
- The distribution of psoriasis on extensor surfaces, scalp and natal cleft helps distinguish psoriasis from discoid eczema.