Optic disc drusen (ODD)  are globules of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc. They are thought to be the remnants of the axonal transport system of degenerated retinal ganglion cells. ODD have also been referred to as congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, and disc hyaline bodies. Anatomy
The optic nerve is a cable connection that transmits images from the retina to the brain. It consists of over one million retinal ganglion cell axons. The optic nerve head, or optic disc is the anterior end of the nerve that is in the eye and hence is visible with an ophthalmoscope. It is located nasally and slightly inferior to the macula of the eye. There is a blind spot at the optic disc because there are no rods or cones beneath it to detect light. The central retinal artery and vein can be seen in the middle of the disc as it exits the scleral canal with the optic nerve to supply the retina. The vessels send branches out in all directions to supply the retina. Pathophysiology
In children, optic disc drusen are usually buried and undetectable by fundoscopy except for a mild or moderate elevation of the optic disc. With age, the overlying axons become atrophied and the drusen become exposed and more visible. They may become apparent with an ophthalmoscope and some visual field loss at the end of adolescence. ODD can compress and eventually compromise the vasculature and retinal nerve fibers.
Psychogenic pruritus, also known as psychogenic itch or functional itch disorder is pruritus not associated with a dermatologic or systemic cause. More often than not, it is attributed to a psychiatric cause. Psychogenic pruritus is not the same as neuropathic itch though both are conditions which require more research. This condition is not explained well in DSM-V and is typically considered a diagnosis of exclusion. This condition is not well-studied and it is difficult to ascertain as it is seen by both dermatologists and psychiatrists. In order to provide some consensus to this condition, The French Psychodermatology Group have created diagnostic criteria for this condition. Symptoms
Psychogenic pruritus typically appears as itching on the face and on the extensor surfaces of the body. This includes the back side of the arms, the abdomen, the side of the legs and the upper back and shoulders. These areas are more frequent because they are within hands reach. Diagnosis
When considering the diagnosis of psychogenic pruritus, it is important to rule out medical, dermatologic and neuropathic causes. A strong history should be obtained and appropriate labwork should be drawn. One should consider drawing for a CBC (Complete Blood Count), ESR (Erythrocyte Sedimentation Rate), liver, renal and thyroid panel as abnormalities with any can contribute to pruritus. Pruritus can be seen with hepatic and renal disease such as cholestasis, alcoholic liver disease, primary biliary cholangitis, hepatitis B and C, and chronic kidney disease.