Rapid, Cost-Effective Diagnosis of Subungual Hematoma

By Arnold Lee MD PhD, Olympia Kovich MD, Alan Greenspan MD, and Hui Yi Shan MD

“Oftentimes dark nail pigments are worrisome for melanoma versus subungual hematoma. Our approach utilizes a simple, specific, and cost-effective method using fecal occult blood test to identify heme, thereby obviating the need for immediate nail biopsy that has been traditionally performed.” -Dr. Arnold Lee

Clinical Issue

Brown and black nail discolorations represent a challenge for clinicians. The differential diagnoses range from potentially lethal melanoma to benign subungual hematoma.

Subungual melanoma has a reported incidence of between 0.7–3.5 percent and accounts for up to one-third of all melanomas in African-Americans, Asians and Native Americans, with a dismal five-year overall survival rate ranging from 40–59 percent.1–3 In contrast, subungual hematomas pose no mortality risk and are most frequently caused by friction with shoes.4

A nail biopsy can be used to differentiate between these two disparate causes. However, nail biopsies can be painful, invasive, challenging to perform and require digit anesthesia block. This procedure can often lead to scarring, which makes both the physicians and patients averse to this procedure.5,6 In addition, costly special histological stains may also be required to identify the dark nail pigment as melanin or blood.

Clinical Bottom Line:

  • The use of a fecal occult blood test kit to confirm dark nail pigment as heme is convenient, highly specific, simple and efficient.
  • Confirmation of subungual pigment as blood can provide some initial reassurance for the patients and clinicians, suggesting the diagnosis of subungual hematoma and not requiring the immediate need to perform an invasive, painful and potentially scar-producing nail biopsy.
  • Even if the subungual pigment tests positive for heme using this test, continued clinical monitoring for the eventual distal migration and disappearance of the dark nail pigment remains critical and essential to rule out subungual melanoma.

Therapeutic Intervention

Here the authors describe an alternative, convenient, non-invasive and easy-to-incorporate method using fecal occult blood test for confirming the nail pigment as heme, not melanin. This assay is inexpensive (<$1.50 per test), has a specificity of 98–99 percent, and takes only one to two minutes to complete, with both internal positive and negative controls.7 A positive reaction will provide some initial reassurance for the patients and allow for continued clinical monitoring for the eventual distal migration of the dark pigment as the nail grows, confirming the diagnosis of subungual hematoma.

A 66-year-old African-American man presented with asymptomatic dark toenail pigmentation of unknown duration. He did not recall any history of trauma. His past medical history and current medications were non-contributory. Physical examination was significant for dark black discoloration of right and left first toenails with mild distal onycholysis (Figures 1a and 1b). More specifically, the discoloration on the left toenail extended from the proximal nail plate to the mid-nail plate whereas that on the right covered about the same region but spared the lunula. To confirm that the subungual pigment was heme and not melanin, both nail plates were gently lifted, and the end of a cotton tip applicator was inserted. Gentle scraping of the nail pigment was performed and transferred to a ColoScan card (StarLine Dealers Association, Richmond, VA), where it tested positive for heme (Figure 2). After seven months, the dark pigmentation disappeared from both nails (Figure 1c).

nail discolorations
FIGURE 1. a) Right toenail, b) Left toenail, c) Left toenail is shown as a representative of both toenails after seven months.

FIGURE 2. a) Right toenail, b) Left toenail. Arrows indicate blue color, which is positive for heme.


While this method can identify the subungual pigment as blood, it must be emphasized that nail hematoma can also result from spontaneous hemorrhage or neovascularization of a tumor such as melanoma.8,9 Therefore, continued clinical monitoring to ensure the eventual distal migration and resolution of the subungual hemorrhage remains essential to rule out a melanoma.


A review of the literature revealed two prior publications regarding diagnostic tests for subungual pigmentation. In 2006, Huang and Ohara described use of a urinanalysis reagent strip for fast identification of blood pigments.4 Poudyal and Elpern, in 2009, discussed the Haneke and the modified Haneke procedures.10

Both approaches involve using punch biopsy without local anesthesia to isolate nail pigment, using either hydrogen peroxide or hemoccult to test for the presence of blood. Interestingly, the authors recommend against using local anesthesia as the patient’s pain sensation serves as a guide of being too close to the nail bed, with the caveat that cutting into the nail bed will be painful to the patient and give a false-positive reaction.

It is worthwhile to point out how this case differs from the other reports. Huang and Ohara used a urinanalysis kit and provided no follow up. Poudyal and Halpern recommended using a more invasive and painful approach with punch biopsy. In contrast, this approach using scrapings from underneath the nail generates less discomfort for the patient without risking any damage to the nail bed. In addition, the authors included a long-term follow-up (seven months), as this is critical since nails typically grow one millimeter per month, and detailed how cost effective this method can be.

In conclusion, the authors have introduced using the fecal occult blood test to verify dark nail pigment as blood and for diagnosing subungual hematoma and provided a real-life example in which the subungual hemorrhage disappeared after seven months, showing that this method can indeed be applied in a clinical setting.


1. Elloumi-Jellouli A, Triki S, Driss M, et al. A misdiagnosed nail bed melanoma. Dermatol Online J. 2010;16:13.

2. Levit EK, Kagen MH, Scher RK, et al. The ABC rule for clinical detection of subungual melanoma. J Am Acad Dermatol. 2000;42:269-274.

3. Cohen T, Busam KJ, Patel A, Brady MS. Subungual melanoma: Management considerations. Am J Surg. 2008;195:244-248.

4. Huang Y-H and Ohara K. Medical pearl: Subungual hematoma: A simple and quick method for diagnosis. J Am Acad Dermatol. 2006;54:877-878.

5. Richert B. Basic nail surgery. Dermatol Clin. 2006;24:313-322.

6. Andre J, Lateur N. Pigmented nail disorders. Dermatol Clin. 2006;24:329-339.

7. ColoScan: A Test for Occult Blood. Helena Laboratories: StarLine USA, 2007.

8. Daniel III CR, Jellinek NJ. Subungual blood is not always a reassuring sign. J Am Acad Dermatol. 2007;57:176.

9. Juten PG, Hinnen JW. A 71-year-old woman with a pigmented nail bed, which persisted after trauma. Acta Chir Belg. 2010;110:475-478.

10. Poudyal S, Elpern DJ. Simple diagnostic tests for subungual pigmentation. Dermatol Res Pract. 2009;2009:278040.

About the author

Arnold Lee MD PhD, Olympia Kovich MD, Alan Greenspan MD, and Hui Yi Shan MD

Dr. Arnold Lee is currently the Associate Director of the Department of Dermatology at Elmhurst Hospital Center (New York) and also works as a Mohs micrographic surgeon at a private practice in New York City. He graduated magna cum laude in Biochemical Sciences from Harvard University and pursued the NIH-funded combined MD-PhD degrees at New York University School of Medicine. His internal medicine preliminary training and dermatology residency were at New York University Medical Center and the world-renowned Bellevue Hospital. Dr. Lee also completed a highly competitive ACGME accredited Procedural Dermatology Fellowship at Mount Sinai Medical Center. He has published extensively in peer-reviewed basic science and medical journals, ranging from experiments on cellular aging with Nobel laureate, signaling molecules pivotal for cancer and normal tissue development, to dermatologic surgical and cosmetic techniques. Drs. Kovich and Greenspan are on staff in the Department of Dermatology at the New York University (NYU) Medical Center, New York, NY; Dr. Shan is in the Department of Medicine at NYU Medical Center.

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