Editing Melanoma (section)

=== '''Histological subtypes''' ===

** Lentigo maligna (Hutchinson melanotic freckle)
*** Can transform into lentigo maligna melanoma
*** Most common on sun-exposed skin of older patients
*** Flat, dark, variably pigmented lesion; irregular borders; slow development
*** Can become quite large prior to diagnosis
*** Better prognosis than other subtypes, but can be hard to excise due to location
*** Histologic extent can be well beyond the clinical borders - best to ensure negative margins prior to complex flap reconstruction
***
** Superficial spreading
*** Most common
*** Not necessarily associated with sun-exposed skin
*** Most commonly seen on trunk and proximal extremities
*** Flat pigmented lesion growing radially; asymmetric; irregular borders
*** Will develop a vertical growth phase if untreated
*** Can ulcerate
***
** Acral lentiginous
*** Classified by anatomic site of origin - arises in subungual areas beneath fingernails and toenails, and on palms and soles
*** Most common type in non-white patients
*** Often mistaken for subungual haematomas (however does not change in position underneath the nail, whereas haematomas move distally with nail growth)
*** Biopsy either by removing the nail or doing a punch biopsy through the nail itself
***
** Nodular
*** Raised papular lesions
*** Can occur anywhere on the body
*** Tend to develop a vertical growth pattern early in their course
*** Poorer prognosis due to thicker tumour at diagnosis
***
** Desmoplastic
*** Combination of melanoma cells with prominent stromal fibrosis
*** Often amelanotic
*** Classified as either pure or mixed, depending on the degree of desmoplasis present
*** Greater propensity for local recurrence, and often exhibit neurotropism
*** Pure desmoplastic - low risk of lymph node metastasis - often forego SLNB
*** Mixed - similar rate compared to subtypes