However, given that most lesions appear in the distal matrix, it may not be necessary to include the proximal matrix in the biopsy, thereby reducing the risk of dystrophy.16,17,25 Nail dermoscopy is useful for the study of longitudinal melanonychia and facilitates identification of the clinical signs of alarm.6,2628 Intraoperative nail dermoscopy (once the nail plate has been removed) can, moreover, more precisely locate the source of pigmentation.5,6,26,29,30 Both longitudinal elliptical and punch biopsies can be used for nail bed biopsies.16,19,21 Given that most pigmentation of melanocytic origin arises in the matrix, an isolated biopsy of the nail bed is insufficient in this context, as the histological material of interest would not be obtained for study.7,9 Isolated biopsies of the matrix are mainly of the elliptical type, in this case, transverse (in general, the first should be transversely oriented),21,31 punch biopsies, and longitudinal excision biopsies, which we will discuss in more detail later.2,14,19,21 Elliptical biopsies and punch biopsies can be performed directly or with prior avulsion of the nail plate.2,5,13,14,19 After avulsion, if the pigmentation studied has a small diameter, a punch biopsy can be performed.2,13,14,19,25 For broad pigmentations, longitudinal transverse biopsy of the matrix is the preferred option.14,19,25 In recent years, shave biopsy of the matrix has received particular attention.5,6,13,21,25,32 This technique is performed after withdrawing the proximal nail fold and avulsion of the proximal plate
This means your body can only make as much glutathione as it has cysteine available
There is no exception to this rule
the antidote for acetaminophen toxicity
