|
.
·
Squamous Cell Carcinoma
o
These lesions occur in sun-exposed and/or X-rayed areas.
o
They
have the potential to metastasize. There is a
higher probability of metastasis if the lesions are
X-ray-induced and on mucous membranes
Melanocytes
A.
Benign Neoplasms
·
Nevocellular Nevus
o
Nevocellular nevi are common tumors that begin at the
dermal-epidermal interface as flat lesions (lentigo
simplex). The lesions may proliferate into 3
areas.
§
Junctional
– cells form nests along the dermal-epidermal interface
§
Compound
– cells proliferate and migrate down into the dermis
§
Intradermal
– cells are entirely in the dermis; intraepidermal part
is lost
o
Unremoved large nevi that occur at birth have a 20-30%
of becoming cancerous during puberty.
·
Spindle & Epithelioid Cell Nevus of Spitz (Juvenile
Melanoma)
o
This
usually occurs in the teenage years or in your 20s.
o
It
is a histological variant of nevocellular nevus.
·
Blue
Nevus
o
The
nevi are pigmented and occur deep in the
dermis. They appear blue due to the Tyndall
effect of the collagen in the overlying skin.
·
Halo
Nevus
o
A
nevus surrounded by an area of depigmentation
due to an immune reaction against melanocytes.
o
This
condition can occur by itself, an autoimmune disease (e.g.
thyroid), or be due to a distant melanoma.
·
Peutz-Jeghers Syndrome
o
Lentigines
(small, sharply circumscribed, pigmented macules) and
ephelides (tanned macules/freckles) are usually
found around the mouth.
o
Benign polyps in the GI tract
can affect the entire bowel, resulting in perirectal
bleeding and abdominal pain. These polyps can become
cancerous.
B. Malignant Neoplasms: Melanoma
·
Superficial Spreading Melanoma
o
This
is the most common type of melanoma, occurring most
frequently in areas of sun exposure.
o
In
the attempt to produce more melanin due to UV exposure,
melanocytes proliferate and begin accumulating toxic
intermediates from the melanin-producing reaction. This
sets the stage for cancer potentiality.
o
In
men, melanomas usually appear on the upper body.
o
In
women, melanomas usually appear in the upper body except
for those areas covered by bathing suits.
J
·
Lentigo Maligna/Lentigo Maligna Melanoma
o
Presents as large lesions on the face, due to
long years of working in the sun
o
Lentigo Melanoma (**Hutchinson’s Freckle**)
is entirely intraepidermal.
o
Lentigo Maligna Melanoma
extends deeper into the dermis.
·
Nodular Melanoma
o
This
is a rapidly spreading superficial melanoma,
growing deep into the dermis. It is not sun-related.
·
Acral-Lentiginous Melanoma
o
This
condition usually occurs in the African American and
Asian populations.
o
It
is similar to Lentigo Maligna Melanoma, but occurs on
the palms, soles, under the nails, and on
mucous membranes. It is not sun-induced.
How Can You Differentiate a Nevus from a Melanoma?
·
Nevus
= regular shape, surface, & color;
non-ulcerating
·
Melanoma
= irregular shape, surface, & color;
ulcerating
Additional Neoplasms
Mast Cells
·
Cutaneous Mastocytosis
o
Widespread proliferation of mast cells
in the skin, found most commonly in kids
·
Urticaria Pigmentosa
o
Hyperpigmented
(Tyndall effect) lesions of mast cells
o
When
the lesions are stroked, urticaria (histamine-induced
edema) occurs.
Cutaneous T Cell Lymphomas (CTCL)
·
Mycosis Fungoides
o
This
condition is a mixed-cell lymphoma of the skin
(not a fungal cause!), containing a T cell with a
convoluted nucleus (Sézàry cell).
o
The
lymphomas look like mushrooms at advanced stages of the
disease.
·
Sézàry Syndrome
o
This
is a variant of Mycosis Fungoides.
o
It
presents as a generalized erythroderma, in which
the whole body is red due to widespread invasion of the
skin by malignant cells (via blood and renal
circulation), with leukemia of Sézàry cells.
Hemangiomas
·
These are benign proliferations of blood vessels in
the skin, which develop mostly during the first year
of childhood. They usually disappear spontaneously
during adolescence.
·
If
this condition occurs systemically into the brain,
Sturge-Weber Syndrome may result.
o
This
is a neurocutaneous disorder characterized by
angiomas involving the leptomeninges and
ipsilateral port-wine nevi of the face.
·
The
port-wine stain is a cutaneous presentation of angiomas
along the distribution of the trigeminal nerve.
It thickens the skin and does not fade.
o
It
is associated with hemiplagia (neurological
deficit on the opposite side of the body), mental
retardation, and seizures.
Back to the Integumentary System
Index
|
