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Section 11 Precancerous Lesions and Cutaneous Carcinomas 233
Helix
Lower
lip
In bald
individuals
Figure 11-6. Squamous cell carcinoma: predilection
sites.
Sex. Males > females, but SCC can occur more
frequently on the legs of females.
Exposure. Sunlight. Phototherapy and PUVA
(oral psoralen + UVA). Excessive photochemotherapy
can lead to promotion of SCC, particularly
in patients with skin phototypes I and II
or in patients with history of previous exposure
to ionizing radiation.
Race. Persons with white skin and poor tanning
capacity (skin phototypes I and II) (see
Section 10). Brown- or black-skinned persons
can develop SCC from numerous etiologic
agents other than UVR.
Geography. Most common in areas that have
many days of sunshine annually, i.e., in Australia
and southwestern United States.
Occupation. Persons working outdoors—farmers,
sailors, lifeguards, telephone line installers,
construction workers, and dock workers.
Human Papillomavirus
Most commonly oncogenic HPV type-16, -18,
-31 but also type-33, -35, -39, -40, and -51 to
-60 are associated with epithelial dysplasia,
SCCIS, and invasive SCC. HPV-5, -8, -9 have
also been isolated from SCCs.
Other Etiologic Factors
Immunosuppression. Solid organ transplant
recipients, individuals with chronic immuno-
suppression of inflammatory disorders, and
those with HIV disease are associated with
an increased incidence of UVR- and HPVinduced
SCCIS and invasive SCCs. SCCs in
these individuals are more aggressive than in
nonimmunosuppressed individuals.
Chronic Inflammation. Chronic cutaneous lupus
erythematosus, chronic ulcers, burn scars,
chronic radiation dermatitis, and lichen planus
of oral mucosa.
Industrial Carcinogens. Pitch, tar, crude paraffin
oil, fuel oil, creosote, lubricating oil, and
nitrosoureas.
Inorganic Arsenic. Trivalent arsenic had been
used in the past in medications such as Asiatic
pills, Donovan pills, and Fowler solution (used
as a treatment for psoriasis or anemia). Arsenic
is still present in drinking water in some geographic
regions (West Bengal and Bangladesh).
Clinical Manifestation
Slowly evolving—any isolated keratotic or
eroded papule or plaque in a suspect patient
that persists for over a month is considered
a carcinoma until proved otherwise. Also,
a nodule evolving in a plaque that meets the
clinical criteria of SCCIS (Bowen disease), a
chronically eroded lesion on the lower lip or
on the penis, or nodular lesions evolving in
or at the margin of a chronic venous ulcer or
within chronic radiation dermatitis. Note that
SCC usually is always asymptomatic. Potential
carcinogens often can be detected only after
detailed history.
Rapidly evolving—invasive SCC can erupt
within a few weeks and there is often painful
and/or tender.
For didactic reasons, two types can be
distinguished:
1. Highly differentiated SCCs, which practically
always show signs of keratinization
either within or on the surface (hyperkeratosis)
of the tumor. These are firm or hard
upon palpation (Figs. 11-7 to 11-9 and Figs.
11-11 and 11-12).
2. Poorly differentiated SCCs, which do not
show signs of keratinization and clinically
appear fleshy, granulomatous, and consequently
are soft upon palpation (Figs. 11-5
and 11-10).
Differentiated SCC
Lesions. Indurated papule, plaque, or nodule
(Figs. 11-1, 11-7 and 11-8); adherent thick