C h a p t e r 4 6
Disorders of Skin Integrity and Function
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Pathogenesis.
Four types of melanomas have been
identified based on their radial and vertical growth pro-
gression: lentigo maligna, superficial spreading, acral
lentiginous, and nodular. Radial growth describes the
horizontal spread of the melanoma within the epider-
mis and superficial dermis. During this initial stage, the
tumor seems to lack the ability to metastasize. Lentigo
maligna melanomas, superficial spreading melanomas,
and acral lentiginous melanomas are tumors that are in
the radial growth phase.
Lentigo maligna melanomas
are flat, slow-growing nevi that may remain in the radial
growth phase for several decades. They are seen primar-
ily on sun-exposed skin of elderly persons.
Superficial
spreading melanoma,
the most common type of mela-
noma, is seen most commonly in persons who sunburn
easily and have intermittent sun exposure. It is charac-
terized by a raised-edged nevus with lateral growth and
a disorderly appearance in color and outline. It typically
ulcerates and bleeds with growth.
Acral lentiginous
melanoma
has an appearance similar to that of lentigo
maligna, and is seen primarily on the palms, soles, nail
beds, and mucous membranes. Its occurrence is unre-
lated to sun exposure.
After a variable and unpredictable period of time,
melanomas shift from a radial to vertical growth phase,
during which the tumor cells invade downward into the
deeper dermis layers.
11
This growth phase is heralded by
the nodular phase and correlates with the emergence of
a clone of cells with metastatic potential.
Nodular mela-
nomas
are raised, dome-shaped lesions that can occur
anywhere on the body. They are commonly a uniform
blue-black color and tend to look like blood blisters.
Nodular melanomas tend to rapidly invade the dermis
from the start, with no apparent horizontal growth
phase.
Diagnosis and Treatment.
Early detection is critical
with malignant melanoma. Regular self-examination of
the total skin surface in front of a well-lighted mirror
provides a method for early detection. It requires that a
person undress completely and examine all areas of the
body using a full mirror, handheld mirror, and hand-
held hair dryer (to examine the scalp). An
ABCD
rule
has been developed to aid in early diagnosis and timely
treatment of malignant melanoma.
64
The ABCD acro-
nym stands for
a
symmetry,
b
order irregularity,
c
olor
variegation, and
d
iameter greater than 6 mm (1/4 inch
or pencil eraser size). People should be taught to watch
for these changes in existing nevi or the development of
new nevi, as well as other alterations such as bleeding or
itching. Because of the existence of small-diameter mela-
nomas (i.e., <6 mm in diameter), it has been suggested
that people routinely screen their skin for all possible
manifestations of skin cancer. Since their description
over 20 years ago, evidence has accumulated to add an
E for “evolving” to the ABCD rule.
68
The E for evolving
is intended to encourage the recognition of melanomas
at an earlier stage by emphasizing the dynamic nature of
their growth.
Diagnosis of melanoma is based on biopsy findings
from a lesion.
64–66
Because most melanomas initially
metastasize to regional lymph nodes, additional infor-
mation may be obtained through lymph node biopsy.
Consistent with other cancerous tumors, melanoma is
commonly staged using the TNM (tumor, lymph node,
and metastasis) staging system (see Chapter 7) or the
American Joint Committee on Cancer Staging System
for Cutaneous Melanoma, in which the tumor is rated
0 to 4 depending on numerous factors, including extent of
tumor invasion, ulceration, and metastasis.
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Ulceration
and invasion of the tumor into the deeper skin tissue
result in a poorer prognosis. The degree and number
of lymph nodes involved correlate well with overall
survival.
Treatment of melanoma is usually surgical excision,
the extent of which is determined by the thickness of the
lesion, invasion into the deeper skin layers, and spread
to the regional lymph nodes.
64–66
Deep, wide excisions
with elective removal of lymph tissue and the use of skin
grafts were once the hallmarks of treatment. When diag-
nosed in a premetastatic phase, melanoma is now treated
in ambulatory settings, lessening the cost and inconve-
nience of care. Current capability allows for mapping
lymph flow to a regional lymph node that receives lym-
phatic drainage from tumor sites on the skin. This lymph
node, which is called the
sentinel lymph node,
is then
sampled for biopsy. If tumor cells have spread from the
primary tumor to the regional lymph nodes, the sentinel
node will be the first node in which tumor cells appear.
Therefore, sentinel node biopsy can be used to test for
the presence of melanoma cells and determine if radi-
cal lymph node dissection is necessary. When nodes are
positive, consideration is also given to systemic adjuvant
therapy. Although no effective chemotherapy is avail-
able for melanoma, interferon alfa-2b is a biologic ther-
apy available for adjuvant treatment of melanoma. At
this time, however, the use of interferon is controversial.
Clinical trials with other therapies, including combina-
tion chemotherapies, vaccines, and hyperthermic isola-
tion limb perfusion, are ongoing.
64–66
Basal Cell Carcinoma
Basal cell carcinoma is a neoplasm of the nonkeratiniz-
ing cells of the basal layer of the epidermis.
67
It is the
most common invasive cancer in humans; approxi-
mately 75% of all skin cancers are basal cell carcino-
mas.
67
Basal cell carcinomas have a tendency to occur in
fair-skinned persons with a history of significant long-
term sun exposure. They are most frequently seen on
the head and neck, most often occurring on skin that
has hair.
Basal cell carcinomas are slow-growing tumors that
extend wide and deep if left untreated, but rarely metas-
tasize. Advanced lesions are often invasive and ulcer-
ative. Risk factors for extensive spread include a tumor
diameter greater than 2 cm, location on the central part
of the face or ears, long-standing duration, incomplete
excision, and perineural or perivascular involvement.
Histologically, the tumor cells resemble those in the
normal basal layer from the epidermis or follicular
epithelium and do not occur on mucosal surfaces.
67
