Case presentation: Subungual melanoma

A Caucasian female presented with a dark brown band on her nail that appeared a few years ago.

Figure 1 (Photo courtesy of Eve Lowenstein, M.D.)

ANSWER

1. Duration

Figure 1 (Photo courtesy of Eve Lowenstein, M.D.)

ANSWER

2. Pigment extension for melanoma beyond nail bed

The presenting sign for subungual melanoma is often a black irregular nail band that changes and widens across the nail. Subungual melanoma is an uncommon type of malignant melanoma, encompassing only 1-2% of cutaneous melanoma in the Caucasian population and 0.7-3.5% of all melanomas (1,2). Persistence of pigment alone does not indicate benign or malignant nature, as a benign nevus can persist for years. The Hutchinson sign, or extension of the pigment onto the proximal or lateral nailfold, while not pathognomonic, is highly correlated with presence of melanoma. Rapid evolution, advancement and change in discoloration is also concerning for melanoma (1). The most common anatomic locations of subungual melanoma include the thumb and hallux (1,2). A history of trauma is not uncommonly reported in melanoma nail lesions, and should not be used to discount the possible diagnosis of melanoma.

Figure 2 (Photo courtesy of Eve Lowenstein, M.D.)

ANSWER

True

Figure 2 (Photo courtesy of Eve Lowenstein, M.D.)

ANSWER

True

Subungual and acral lentigenous melanomas are more common in dark skinned individuals.  However, nail pigmentation that is benign is also much more common in this population.  However, an irregular multi-colored band (as opposed to multiple similar appearing bands which may be seen from drugs or recurrent trauma) are concerning for subungual melanoma (3).

 In the western hemisphere, subungual melanoma accounts for 2% of non-sun induced melanomas of the skin. Subungual melanoma accounts for 75% of melanoma in Africans, 10% of Japanese, and 25% of Chinese in Hong Kong (4,5).

Figure 2 (Photo courtesy of Eve Lowenstein, M.D.)

ANSWER

5. All of the above

As the ABCDE rule has already been linked to diagnosis of cutaneous melanoma, a study associated ABCDEF with diagnosis of subungual melanoma using dermoscopy.  A stands for Age (5th to 7th decades of life; one third of cases in Asians, African Americans, and Native Americans); B stands for brown to black; breadth of 3 mm or more and variegated borders; C stands for change in nail bed or absence of change in nail appearance despite treatment; D stands for digit most frequently involved; E stands for extension of pigment onto proximal/lateral nail fold (Hutchinson’s sign); F stands for family or personal history of dysplastic nevus or melanoma (6).

Figure 2 (Photo courtesy of Eve Lowenstein, M.D.)

ANSWER

3. Dry nails

Subungual melanoma often presents as nail discoloration, and may gradually develop into a stubborn wound, tumor, nail splitting, or nail bed bleeding. Most of the time, subungual melanoma is found at a more advanced stage due to several years of waiting by the patient before consultation of a physician or a very atypical presentation. This melanoma subtype is commonly misdiagnosed as subungual hematoma, chronic trauma, or onychomycosis (7).

Figure 2 (Photo courtesy of Eve Lowenstein, M.D.)

ANSWER

2. No

As ultraviolet radiation is not likely to access the nail plate, sun exposure has not been shown to be linked as a risk factor for subungual melanoma (5).

REFERENCES

Braun S, Gerber P. Subungual malignant melanoma. CMAJ. 2015 Sep;187(12):909.

Nocera NF, Baruch MI, Kim M. Subungual melanoma of the thumb. Eplasty. 2013;13:ic26.

Hamblin MR, Avci P, Gupta GK. Imaging in Dermatology. 1st ed. Academic Press; 2016.

Patel GA, Ragi G, Krysicki J, et al. Subungual melanoma: a deceptive disorder. Acta Dermatovenerol Croat. 2008;16(4):236-42.

Möhrle M, Häfner HM. Is subungual melanoma related to trauma? Dermatology. 2002;204(4):259-61.

Levit EK, Kagen MH, Scher RK, et al. The ABC rule for clinical detection of subungual melanoma. J Am Acad Dermatol. 2000 Feb;42(2 Pt 1):269-74.

De Giorgi V, Saggini A, Grazzini M, et al. Specific challenges in the management of subungual melanoma. Expert Rev Anticancer Ther. 2011 May;11(5):749-61.