Subungual melanoma - Altmeyers Encyclopedia

Synonym(s)

Acral lentiginous melanoma; Nail melanoma; Subungual malignant melanoma; Subungual melanoma

Definition
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Rare (1-2% of all malignant melanomas) variant of acrolentiginous malignant melanoma. In Asia, however, the incidence is 20-30%.

Occurrence/Epidemiology
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1-2% of all malignant melanomas

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Dermatology

Melanonychia

Polyätiological, mostly painless, localized - streaky or roundish - but also diffusely homogeneous, black o...

Manifestation
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Age at diagnosis 55-65 years.

Localization
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Preferably the fingernails (61%) and here especially the thumbnails are affected.

Clinical features
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The first clinical sign is the longitudinal stripe-like melanonychia (see also there for differential diagnosis), often accompanied by a periungual hyperpigmentation ( Hutchinson sign).

Progressive growth of the pigment tumor leads to a grey-black discoloration of the nail and later to a clumsy lifting and destruction of the nail plate.

In about 30% of cases amelanotic subungual melanomas develop. These are less painful, reddish tumors with a destroyed or lifted nail plate. Also missing is the otherwise obligatory longitudinal stripping of the nail plate.

Helpful for the clinical classification of a subungual melanoma is the ABC rule defined by Levit EK et al:

A = Age, higher age, 5th-7th decade
B = Pigmented band: band-shaped pigmentation, brown-black, >0,3cm (see fig.)
C = Change: recent rapid change in width and/or nail plate morphology
D = Single digit involvement: concerns only 1 nail, most often thumb, followed by big toe or index finger
E = Extension of the pigment into the perinychium (Hutchinson sign)
F = Family history (melanoma, dysplastic nevi syndrome)

Diagnosis
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Diagnostic confirmation, e.g. via histological detection of melanin in the nail plate (Fontana-Masson staining).

Therapy
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In case of melanocytic origin nail extraction and excision of the pigmented part in the nail bed with sufficient safety distance, if necessary amputation of the affected digitus.

Literature
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Baccard M et al (2009) Acrolentiginous melanoma. Ann Dermatol Venereol 136:389-390
Baumert J et al. (2009) Time trends in tumor thickness vary in subgroups: analysis of 6475 patients by age, tumor site and melanoma subtype. Melanoma Res 19:24-30
Gutman M et al (1985) Acral (volar-subungual) melanoma. Br J Surg 72: 610-613.
Koushk Jalali B et al (2018) Subungual melanoma. CMAJ. Aug 27;190(34):E1018. doi: 10.1503/cmaj.180513.
Levit EK et al (2000) The ABC rule for clinical detection of subungual melanoma. J Am Acad Dermatol 42:269-274.
Mishima Y, Nakanishi T (1985) Acral lentiginous melanoma and its precursor--heterogeneity of palmo-plantar melanomas. Pathology 17: 258-265
Schmidt-Wendtner et al (2003) Disease progression in patients with cutaneous melanomas (tumor Thickness < 0,75 mm): clinical and epidemiological data from the tumor center Munich 1977-1998. Br J Dermatol 149: 788-793.
Schoenewolf NL et al (2012) Sinonasal, genital and acrolentiginous melanomas show distinct characteristics of KIT expression and mutations. Eur J Cancer 48:1842-1852
Tuominen L, Strengell L (1992) Melanoma of palms, soles, and nail-beds. Scand J Plast Reconstr Surg Hand Surg 26: 287-292.