Evaluation of Nail Lines: Color and Shape Hold Clues
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REVIEW SHARI R. LIPNER, MD, PhD RICHARD K. SCHER, MD, FACP Assistant Professor of Dermatology, Clinical Professor of Dermatology, Weill Cornell Weill Cornell Medical College, New York, NY Medical College, New York, NY Evaluation of nail lines: Color and shape hold clues ABSTRACT nspection of the fingernails and toenails Ishould be part of a complete physical exami- Nail lines are a common presenting fi nding. A thorough nation. A basic understanding of nail anatomy inspection of the fi ngernails and toenails is an integral and recognition of several basic types of nail part of the complete physical examination. An under- lines and bands allow the clinician to properly standing of basic nail anatomy and familiarity with sev- diagnose and treat the nail disease, to recog- eral basic types of nail line enable the clinician to diag- nize possible underlying systemic diseases, and nose and treat nail disorders and to recognize underlying to know when to refer the patient to a derma- systemic diseases, as each type of nail line has a particu- tologist for specialized evaluation and biopsy. lar differential diagnosis. The authors review leukonychia In this review, we delineate the three basic striata (white lines), longitudinal melanonychia (brown- types of nail lines —white lines (leukonychia black lines), longitudinal erythronychia (red lines), and striata), brown-black lines (longitudinal mela- nonychia), and red lines (longitudinal ery- nail-plate grooves (Beau lines). thronychia)—and the differential diagnosis KEY POINTS for each type. We also discuss grooves in the nail plate, or Beau lines. Transverse white nail lines, or Mees lines, have been as- sociated with acute systemic stress, such as from acute ■ BASIC NAIL ANATOMY renal failure, heart failure, ulcerative colitis, breast cancer, A fundamental understanding of the anatomy infection (measles, tuberculosis), and systemic lupus of the nail unit is necessary to understand the erythematosus, and with exposure to toxic metals such as origin of nail diseases and underlying patho- thallium. logic conditions. The nail unit includes the nail matrix, the In true leukonychia, there is abnormal keratinization lunula, the nail fold, the nail plate, and the of the underlying nail matrix, resulting in a white dis- nail bed. The nail matrix extends from under coloration that is unaffected by pressure. In apparent the proximal nail fold to the half-moon-shaped leukonychia, the white discoloration is due to abnormal area (ie, the lunula) and is responsible for nail plate production. The nail bed lies under the nail bed vasculature, and the whiteness disappears with nail plate and on top of the distal phalanx and pressure. extends from the lunula to just proximal to the free edge of the nail; its rich blood supply gives Brown-black nail lines may represent blood from trauma; it its reddish color. bacterial, fungal, or viral infection; drug reaction; endo- Nails grow slowly, and this should be kept crine disorders; exogenous pigmentation; excess melanin in mind during the examination. Regrowth of production within the nail matrix; nevi; or melanoma. a fi ngernail takes at least 6 months, and re- growth of a toenail may take 12 to 18 months. Therefore, a defect in the nail plate may reveal an injury that occurred—or a condition that doi:10.3949/ccjm.83a.14187 began—several months before.1 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 83 • NUMBER 5 MAY 2016 385 Downloaded from www.ccjm.org on October 2, 2021. For personal use only. All other uses require permission. NAIL LINES FIGURE 1. Onychomycosis of the great toe- FIGURE 2. “Half-and-half” nails involve a transverse white nail resulting in a dermatophytoma, visible band proximally and a red-brown band distally. Underly- as a white-yellow longitudinal band. ing conditions include Kawasaki disease, cirrhosis, Crohn disease, and zinc defi ciency. ■ NAIL EXAMINATION ESSENTIALS True leukonychia A complete examination includes all 20 Leukonychia striata, a subtype of true leuko- nail units and the periungual skin. Patients nychia, is characterized by transverse or longi- tudinal bands. It is most often associated with should be instructed to remove nail polish 4 from all nails, as it may camoufl age dystro- microtrauma, such as from a manicure. Lines Onychomycosis phy or disease of the nail. Photography and due to trauma are typically more apparent in the central part of the nail plate; they spare causes white careful measurement help document changes over time. the lateral portion and lie parallel to the edge nail lines and of the proximal nail fold.5 Onychomycosis. White longitudinal bands accounts for ■ LEUKONYCHIA STRIATA: WHITE NAIL LINES may also be seen in onychomycosis, a fungal half of all cases infection of the nail accounting for up to 50% of nail disease White nail lines or leukonychia is classifi ed as of all cases of nail disease. The infection may true or apparent, depending on whether the present as irregular dense longitudinal white origin is in the nail matrix or the nail bed. or yellowish bands or “spikes” on the nail plate In true leukonychia, there is abnormal with associated hyperkeratosis, known as a keratinization of the underlying nail ma- dermatophytoma (Figure 1). trix, resulting in parakeratosis within the If a fungal infection is suspected, a potas- nail plate and an opaque appearance on ex- sium hydroxide stain can be performed on the amination.2 The white discoloration is un- subungual debris, which is then examined with affected by pressure, and the opacity moves direct microscopy.6 Alternatively, the physi- distally as the nail grows out, which can be cian can send a nail plate clipping in a 10% documented by serial photography on sub- buffered formalin container with a request for sequent visits. a fungal stain such as periodic acid-Schiff.7 Mi- Apparent leukonychia involves abnor- croscopic examination of a dermatophytoma mal nail bed vasculature, which changes the shows a dense mass of dermatophyte hyphae, translucency of the nail plate. The whiteness otherwise known as a fungal abscess.8 disappears with pressure, is unaffected by nail The physician can play an important role growth, and will likely show no change on in diagnosis because clinical fi ndings sugges- later visits with serial photography.3 tive of a dermatophytoma are associated with 386 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 83 • NUMBER 5 MAY 2016 Downloaded from www.ccjm.org on October 2, 2021. For personal use only. All other uses require permission. LIPNER AND SCHER a poor response to antifungal therapy.9 A B Inherited diseases. White longitudinal bands are also an important clue to the rare autosomal dominant genodermatoses Hailey- Hailey disease (from mutations of the ATP2A2 gene) and Darier disease (from mutations of the ATP2C1 gene). Patients with Hailey-Hai- ley disease may have nails with multiple paral- lel longitudinal white stripes of variable width originating in the lunula and most prominent on the thumbs.10–12 These patients also have recurrent vesicular eruptions in fl exural skin areas, such as the groin, axilla, neck, and peri- umbilical area causing signifi cant morbidity. Patients with Darier disease may have nails with alternating red and white longitu- dinal streaks, described as “candy-cane,”13 as FIGURE 3. Longitudinal melanonychia presents as one or well as wedge-shaped distal subungual kerato- more longitudinal brown-black bands in the nail plate. sis accompanied by fl at keratotic papules on Underlying conditions include melanoma in situ (A) and the proximal nail fold.14 These nail changes benign nevus (B). are reported in 92% to 95% of patients with Darier disease.15,16 Patients typically have skin Muehrcke lines are paired white trans- fi ndings characterized by keratotic papules verse bands that span the width of the nail and plaques predominantly in seborrheic ar- bed and run parallel to the distal lunula. They eas and palmoplantar pits, as well as second- were fi rst described in the fingernails of pa- ary infections and malodor causing signifi cant tients with severe hypoalbuminemia, some of morbidity.15 Therefore, knowing the charac- whom also had nephrotic syndrome, which teristic nail fi ndings in these diseases may lead resolved with normalization of the serum al- Black-brown to more rapid diagnosis and treatment. bumin level. Muehrcke lines have since been vertical lines reported in patients with liver disease, malnu- Mees lines. Leukonychia striata can pres- may represent ent as transverse white lines, commonly trition, chemotherapy, organ transplant, hu- known as Mees lines. They are 1- to 2-mm man immunodefi ciency virus (HIV) infection, nail trauma, 3,18 wide horizontal parallel white bands that span and acquired immunodefi ciency syndrome. infection, the width of the nail plate, usually affecting They are associated with periods of metabolic all fi ngernails.17 They are not a common fi nd- stress, ie, when the body’s capacity to synthe- endocrine ing and are most often associated with arsenic size proteins is diminished.19 disorders, Half-and-half nails, or Lindsay nails, are poisoning. They can also be used to identify melanoma, or the time of poisoning, since they tend to ap- characterized by a white band proximally, a pear 2 months after the initial insult. pink or red-brown band distally, and a sharp benign nevi Mees lines are also associated with acute demarcation between the two (Figure 2). systemic stresses, such as acute renal failure, They were originally described in association 20 heart failure, ulcerative colitis, breast cancer, with chronic renal disease, and surprisingly, infections such as measles and tuberculosis, they resolve with kidney transplant but not and systemic lupus erythematosus, and with with hemodialysis treatment or improve- 21–23 exposure to toxic metals such as thallium.3 ment in hemoglobin or albumin levels. Half-and-half nails have been reported with Apparent leukonychia Kawasaki disease, hepatic cirrhosis, Crohn Apparent leukonychia can alert the physician disease, zinc defi ciency, chemotherapy, Behçet to systemic diseases, infections, drug side ef- disease, and pellagra.3,24,25 They should be dis- fects, and nutrient defi ciencies.