The crescent of the fingernail, professionally known as the nail half-moon, is a normal physiological structure.
The nail is a plate-like structure formed by the thickening of the cells of the cuticle of the epidermis. The growth site of the nail is the nail matrix, which is located near the proximal underside of the nail plate. Most of the structure is covered by the peri-nail skin, while a small portion of the uncovered nail matrix can be seen through the nail plate in the shape of a white crescent.
Under normal circumstances, the nail half-moon may be large or small, and may even be absent from some nails, and usually diminishes and disappears with age, so the size of the finger crescent is a great individual difference, and has no direct relationship with the state of health.
However, when the nail matrix and nail bed are affected by certain diseases, it will blur the boundary between the nail half-moon and the nail bed, and the crescent will visually appear smaller or disappear.
In conclusion, if the blurring or disappearance of the crescent occurs within a short period of time, and the patient is accompanied by obvious physical symptoms, we should be alert to the possibility of certain diseases, and then we should actively go to the dermatology department for diagnosis and treatment.