Melanotan-associated melanoma

Madam, Melanotan (Ac‐Nle‐Asp‐His‐d‐Phe‐Arg‐Trp‐Lys‐NH2, C50H69N15O9), an α‐melanocyte stimulating hormone analogue, stimulates melanogenesis.1 2–3 These synthetic analogues target the melanocortin type 1 receptor (MC1R), overexpressed in melanoma.4 Currently, the uncontrolled and unlicensed use of melanotan is ever expanding.5 It can be purchased as subcutaneous injection or nasal spray without medical prescription from the internet and is often sold in gyms, spas, fitness studios and tanning parlours. Recently, serious concerns have been raised in respect to the safety of melanotan, in particular the effects on melanocytic naevi. The appearance of atypical pigmented naevi and the change of pre‐existing pigmentary lesions into dysplastic‐like naevi have been reported.6 7–8 A melanoma was reported in a melanotan I user, but without a clear incrimination of afamelanotide use.9 We present a 42‐year‐old white woman with a suspicious enlargement and a change of colour of a pigmentary naevus on the abdomen (Fig. 1a). She presented numerous naevi and was examined yearly by her dermatologist. Previous follow‐ups were always unremarkable. The changes appeared progressively over a 3‐month period after subcutaneous injections of melanotan II (100 mg daily for 2 days, followed by 50 mg daily for 5 days) into the abdominal region. She also noted significant tanning. New naevi had appeared and other pre‐existing naevi presented enlargement and/or darkening. Due to nausea, a melanotan‐related adverse effect, she did not pursue further injections. No other medication apart from oral hormonal contraception was taken. She had a phototype III skin complexion and visited the tanning parlour occasionally. There was no hereditary history of melanoma or other cancers. She had experienced sunburns in her youth. Clinical examination suggested melanoma (Fig. 1a) and dermoscopy was highly suspicious for melanoma (Fig. 1b). The lesion was excised and histology revealed a melanoma (Breslow thickness 0·30 mm, Clark level II). Immunohistochemical staining showed positive S100a, HMB45, Melan‐A, NKIC3 and tyrosinase expression, confirming melanoma. The proliferation marker Ki‐67 was estimated at 10%. There were no local micrometastases or superficial ulceration. Further clinical examination was normal and no lymphadenopathies were evidenced. The area was re‐excised with the recommended surgical margin of 0·5 cm.