Page 77 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 3-12 Malignant Growths

MUCOCUTANEOUS MALIGNANT MELANOMA
MELANOMA

Risk factors include:
Malignant melanoma is one of the few types of cancers
that has continued to increase in incidence over the past UVA and UVB
century. Currently, the incidence of melanoma in the radiation
United States is 1 in 75 Caucasians; this is projected
to continue to increase over the next few decades.
However, the rate of mortality from melanoma has Family history
dropped, probably as a result of early detection and of melanoma or
surgical intervention. According to cancer registries, dysplastic nevi
melanoma ranks sixth in incidence for men and seventh Blue eyes Blonde hair
for women. Melanoma is the most common cancer in Freckles and fair skin
women aged 25 to 30 years. Approximately 700,000
cases of melanoma were diagnosed in the United States Blistering
in 2009, and approximately 9000 people died from sunburn in
complications directly related to melanoma. adolescence
Clinical Findings: Melanoma follows a characteristic
growth pattern. The tumor arises de novo from previ- Melanoma (skin or
mucous membranes)
ously normal skin in approximately 60% of cases and
from preexisting melanocytic nevi in the remaining
40% of cases. Melanoma is uncommon in children, the
one exception being melanoma arising from giant con-
genital nevi. The incidence of melanoma peaks in the
third decade of life and remains fairly stable over the
next 5 decades. There is no gender predilection. Mela-
noma is more common in the Caucasian population.
There are regional variances in distribution of mela- Excisions of lesions Lesions
noma. The back is more commonly involved in men Clinical considerations <2 mm thick
and the posterior lower legs in women. However, mela- Typical clinical appearance of melanoma
noma has been described to occur in any area of the exhibiting features of “ABCDE” mnemonic
skin and mucous membranes. Melanoma has also been A) Asymmetry
shown to develop within the retinal melanocytes, B) Border irregularity Lesions
causing retinal melanoma. This rare tumor is often C) Color variation >2 mm
found incidentally on routine ophthalmological D) Diameter >6 mm thick 1 cm
examination. E) Evolving or changing
Melanoma has been described using the ABCDE Wide local excision of melanoma is based
mnemonic: asymmetric, irregular border, variation in on the thickness of the tumor. A 1-cm
color, diameter greater than 6 mm, and evolving or border is recommended for lesions less 2 cm
changing. These are rough guidelines and are not than 2 mm thick, and a 2-cm border for
meant to be used to diagnose melanoma. They are lesions greater than 2 mm thick.
intended to be used by the lay public to increase aware-
ness and as a method to screen for melanoma. Some
melanomas have all of the ABCDE characteristics, and
some have only one or two of them. Some variants of
melanoma do not follow the ABCDE rules at all, but
these are extremely rare.
There are four main variants of melanoma. The most Melanoma with a Breslow
common one is the superficial spreading type, followed depth of 0.7 mm. Dermal
by the nodular type. Lentigo maligna melanoma and invasion is evident, and the
acral lentiginous melanoma make up the remaining tumor shows an abnormal
types. Rare variants are also seen, including the amela- proliferation of melanocytes
notic type and the nevoid type. Superficial spreading within the epidermis.
melanoma is the most common variant of melanoma
seen in clinical practice. It usually manifests as a slowly
enlarging, irregularly shaped macule with variegation
in color. If not recognized and removed, the melanoma
will continue to enlarge and will eventually develop
a vertical component that clinically represents the
nodular form of melanoma. Some nodular forms of
melanoma can develop de novo without the preceding
superficial spreading type of melanoma as a precursor
lesion. Nodular lesions are often relatively large at the its development. The lesions are often located on especially in those with a considerable sun exposure
time of diagnosis. This type of melanoma has entered the soles, toes, or hands. Patients are often unaware history. This type of melanoma can be difficult to treat
its vertical growth phase, and it is believed that at this of their presence, and they can mimic a subungual and has a propensity for local recurrence. The borders
point it has developed the ability to metastasize. hematoma or bruise. Notably, this form of melanoma of the melanoma are ill defined, and it is difficult to
Acral lentiginous melanoma has long been thought is more commonly seen in the African American distinguish the background normal sun-damaged mela-
to portend a poor prognosis. This is most likely population. nocytes from the tumor cells.
not because of the subtype but because this type of Lentigo maligna melanoma is most often seen on the Amelanotic melanoma is the most difficult of all
melanoma is often diagnosed later in the course of face of patients in their fifth to seventh decades of life, melanomas to diagnosis. These tumors often appear as

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 63