Muehrcke Lines of the Fingernails Clinical Presentation

Updated: Apr 12, 2021
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Muehrcke lines of the fingernails is a transverse leukonychia. [33] They may be evident on both fingernails and toenails. [34] A complete and detailed history is necessary and should include questions concerning occupation and medications. Attention to the chronologic sequence of the events related to the nail abnormality is important. The personal history and a review of systems may also provide important clues to the etiology of the nail changes. Systemic anticancer drug nail changes may cause pain and functional impairment, particularly with taxanes or EGFR inhibitors, but Muehrcke lines are not linked with nail symptoms. [35]


Physical Examination

The two transverse bands originally described by Muehrcke run parallel to the lunule. The bands are separated from each other and from the lunule by areas of normal pink nail, they are not palpable, and they do not indent the nail itself. The distal white band may be wider than the proximal band. The lines are usually found on the second, third, and fourth fingernails; they rarely occur on the thumbnail. [1] The lines are more pronounced with severe and prolonged hypoalbuminemia, and in some patients, they can be reduced or eliminated by intravenous administration of salt-poor serum albumin. They may also be seen following chemotherapy and constitute an aesthetically unpleasant adverse effect of medication and an easily observed sign indicative of previous use of cytotoxic therapy for malignancy. [33]

The physical examination of the nails is valuable in providing clues to the etiology of the nail abnormality. Therefore, a detailed and efficient examination of the nails, in addition to an examination of the rest of the skin and mucous membranes, is essential. Perform a complete physical examination if indicated.

Daniel [8, 36] highlighted a few important points relating to the examination of abnormal nails. If these tests are performed, they provide a more accurate examination. Note the following:

  • Always examine all 10 fingernails and all 10 toenails (and any additional digits if they exist). For the most part, fingernails provide more subtle information than toenails because trauma is more likely to change or hide certain clinical manifestations in toenails and because they grow more slowly.

  • Study the nails with the fingers completely relaxed and not pressed against any surface. Failure to do so may affect the nail hemodynamics and change the appearance of the nail.

  • Blanch the fingertip to see if the pigmented abnormality is grossly altered. This test may aid in differentiating the discoloration of the vascular bed of the nail from the discoloration of the nail plate.

  • Illumination of the nail can be achieved with a penlight placed against the finger pulp shining up through the nail. If the discoloration is in the matrix or soft tissue, its exact position can be more easily identified. If upon illumination, the discoloration disappears, it is more likely to be in the vascular bed.

  • Try scraping the surface of the nail plate, or try cleansing locally or cleansing with a solvent (eg, acetone). If in doing so, the discoloration goes away, the cause of the nail alteration is most likely a topical agent. If, however, as a result, the substance used is impregnated further into the nail or subungually, other studies (eg, nail composition studies; potassium hydroxide preparations; biopsy with light microscope, electron microscope, or special staining) may be indicated.

  • Nail changes associated with systemic disease (as opposed to trauma) often occur in the matrix so that the leading edge of the abnormality (pigmentation) is usually shaped like the distal portion of the matrix. To estimate the time at which the initial insult occurred, one can measure the distance from the proximal nail fold (cuticle) to the leading edge of the pigmentation change. The rate of nail growth is about 0.1-0.15 mm/d. [8]