Is A Black Stripe Worth The Hype?

Yuvraj S. Chowdhury, Mrinali Shetty

November 16, 2019

A 63 year-old Hispanic female presented to clinic for an adult wellness visit.  Her only complaint was that she had noticed discoloration of the nail on her left index finger which she first observed 1 month ago.  She gave no history of trauma to the nail. Examination revealed a longitudinal pigmented stripe occupying about 1/3 of the nailbed. It extended from the distal end of the nail to its base, involving the nail bed (Hutchinson’s sign).  It was not tender to palpation. No axillary lymph nodes could be appreciated. Given the high suspicion for subungual melanoma, the patient was urgently referred to dermatology but was lost to follow up. 

Question:

Which of these statements regarding "Hutchinson's sign" is true?:

1. It is present in Laugier-Hunziker syndrome and Bowen’s disease of the nail plate

2. It is not seen in amelanotic melanoma, a subtype of acral lentiginous subungual melanoma

3. When associated with malignant melanoma, it is usually late presenting, heralding a poorer prognosis

4. “Pseudo-Hutchinson’s sign” refers to periungual pigmentation due to melanin within the nail being visible through the translucent edges of the proximal nail fold as it recedes to the cuticle

5. All the above 

Answer:

e.  All of the above

Discussion:

Subungual melanomas are rare lesions present in 1-3% in all melanoma cases [1].  Unlike other melanomas, their association with sunlight has not been established.  They occur more frequently in those of African-American descent but have the poorest prognosis amongst Hispanic whites and Asian/Pacific Islanders.  Differential diagnoses include melanonychia (black or brown pigmentation of the nail plate), which is seen in most African-Americans over the age of 60; trauma causing hematoma formation; systemic disease such as alkaptonuria, AIDS and hemosiderosis; post-inflammatory changes due to lichen planus; and fixed drug eruption from doxorubicin, minocycline, zidovudine and cyclophosphamide [2]. Hematoma may be distinguished from a melanoma as it collects in irregular pools with adjacent drops of purplish-brown discoloration.  It tends to eventually grow out. In contrast, melanomas appear as well organized, continuous bands in the longitudinal axis, arising from the matrix and extending to the distal edge. Dermoscopy is useful to better visualize pigment on the nail folds or digital pulp, referred to as “melanotic whitlow” or “Hutchinson’s sign”[3]. It is important to note that this sign is not pathognomonic for malignancy and may be present in other non-malignant conditions such as Laugier-Hunziker syndrome, Peutz-Jegher syndrome and congenital nevus.  Characteristics of melanoma may be easily memorized by the acronym “ABCDEF” [4]i.e. 

A: Age – peak incidence during 5th-7th decade, African-Americans

B: Brown-black, Breadth: (≥3mm), Borders: variegate

C: Change in nail plate or lack of change despite presumed adequate therapy

D: Digit - Thumb > hallux > index finger; Single digit > multiple digits

E: Extension of pigment to involve the proximal or lateral nail fold (Hutchinson’s sign) or free edge of the nail plate 

F: Family or personal history of previous melanoma or dysplastic nevus syndrome

Subungual melanomas tend to be more advanced at presentation due to delay in diagnosis but also due to a more aggressive proliferative process.  Histological subtypes include: acral lentiginous (most common), lentigo maligna, superficial spreading and nodular. Definitive diagnosis is made by biopsy.  Treatment depends on extent of invasion. Melanoma in situ can be treated with wide local excision. 

References:

1. Thai, K.E., R. Young, and R.D. Sinclair, Nail apparatus melanoma. Australas J Dermatol, 2001. 42(2): p. 71-81; quiz 82-3.

2. Andre, J. and N. Lateur, Pigmented nail disorders. Dermatol Clin, 2006. 24(3): p. 329-39.

3. Baran, R. and P. Kechijian, Hutchinson's sign: a reappraisal. J Am Acad Dermatol, 1996. 34(1): p. 87-90.

4. Levit, E.K., et al., The ABC rule for clinical detection of subungual melanoma. J Am Acad Dermatol, 2000. 42(2 Pt 1): p. 269-74.

Authors (up to date as per time of submission):

Yuvraj S. Chowdhury MD

Dr. Chowdhury is a resident physician in the Department of Internal Medicine at Saint Peters University Hospital-Rutgers RWJ Medical School. He went to medical school in Pune, India after being awarded the Azad Scholarship for Academic Excellence in Biomedical Sciences by the President of India. His current areas of interest include Interventional Cardiology and Heart Failure. He is a member of the ACP-NJ Governer’s Council where his focus is International Medicine Graduate Wellness. 

Mrinali Shetty MD

Dr. Shetty is a PGY-2 internal medicine resident at Saint Peter’s University Hospital, New Brunswick, NJ.