LAUSR

569 lesion was performed and confirmed a superficial spreading melanoma with Breslow depth of 1.5 mm and a mitotic index of 2/mm2 (Stage 1B). The patient then had a 2-cmwide local excision of the scar with closure requiring a full-thickness skin graft and sentinel lymph node biopsy of the left axilla which were both negative for melanoma. Amelanotic melanoma is a subtype with no pigment on clinical inspection [1]. Completely amelanotic lesions are rare whilst hypomelanotic lesions with slight pigmentation are more common [2]. Around 2 to 8% of all melanomas are reported to be amelanotic [3]. Any melanoma can be amelanotic, but it is most common in the subungual and desmoplastic subtypes which often occur in older persons in sun-exposed skin. In females, amelanotic melanomas are mostly found on the limbs, and in males they are more often found on the trunk [2]. They can present as a red macule or patch or a skin-coloured nodule, and the lack of pigmentation makes clinical diagnosis challenging [3]. The lack of pigment may be due to the poor differentiation of the amelanotic subtype, but pigmentation also depends on an individual’s skin phototype and genetics [2]. The prognosis mostly depends on tumour thickness as in other melanomas and is less favourable in amelanotic cases which may be due to diagnostic and treatment delays [2]. Dermoscopy has been reported to be superior to clinical examination in the diagnosis of amelanotic melanoma [3]. As there is often no pigment network to analyse, dermoscopy focuses on identifying vascular structures. “Polymorphic” vessels may be seen where more than one type of vessel can be present with dotted and linear irregular vessels. White lines are also a marker of malignancy as in conventional melanoma [2]. Other reports note milky red areas or globules where the red colour is thought to indicate increased vascular volume and neoangiogenesis [4]. Further reports have noted scar-like depigmentation, ulceration, coiled or tortuous vessels [2], and hairpin vessels [1] in amelanotic cases. In summary, a high index of suspicion may be required to diagnose amelanotic melanoma due to the lack of pigment in these lesions. This case highlights the need to include amelanotic melanoma as a differential for suspicious erythematous lesions. References