Amelanotic melanomaBMJ 2018; 360 doi: https://doi.org/10.1136/bmj.k826 (Published 15 March 2018) Cite this as: BMJ 2018;360:k826
- Andy J Muinonen-Martin, consultant dermatologist1 2 3,
- Sally Jane O’Shea, consultant dermatologist2 3,
- Julia Newton-Bishop, professor of dermatology3
- 1York Teaching Hospital NHS Foundation Trust, York, UK
- 2Leeds Teaching Hospitals NHS Trust, Leeds, UK
- 3Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UK
- Correspondence to S J O’Shea
What you need to know
Amelanotic melanomas represent 8% of all melanomas
They can lack classical features of other melanomas and tend to be red or skin coloured and more symmetrical
They might be confused with basal cell or squamous cell carcinomas, pyogenic granulomas, or benign acral nail lesions, depending on their appearance
A 50 year old woman developed a bleeding nodule on the tip of the right index finger. She reported no history of trauma and said that the mass had developed spontaneously one month before. She was an avid gardener. Her general practitioner diagnosed a pyogenic granuloma and cauterised it, which reduced its size, but the lesion failed to clear. Further cautery was applied 12 weeks later. When this second treatment also failed to completely control the lesion, the woman was referred to the plastic surgery hand clinic, where a biopsy was carried out. A diagnosis of amelanotic malignant melanoma was made. Amputation of the terminal phalanx was performed to achieve wide local excision and a sentinel node biopsy.
Amelanotic melanomas are less common and tend to be difficult to diagnose. This article provides a summary of the key clinical features and will help readers to recognise and refer such lesions appropriately.
What is amelanotic melanoma?
In an amelanotic melanoma most of the melanoma tumour cells are no longer manufacturing pigment (melanin) or are making so little melanin that it is not readily recognised.
There are four main subtypes of cutaneous melanoma: superficial spreading, nodular, lentigo maligna, and acral lentiginous. Melanoma of the skin is most commonly of the superficial spreading type (fig 1A), which often arises in a melanocytic naevus but can arise de novo. These lesions develop over months or years.
How common is amelanotic melanoma?
Amelanotic melanomas are rare overall, estimated to represent 8% of all melanomas.1 …