Page 25 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 1-10 Anatomy, Physiology, and Embryology

MORPHOLOGY: MACULES, PATCHES, AND VESICULO-PUSTULES

MORPHOLOGY (Continued)

be present. Most authors agree that nodules are typi-
cally larger than 1 cm in diameter, and they can be
much larger.
A tumor is generally considered to be larger than
2 cm in diameter, and the term should be reserved
exclusively for the description of malignant neoplasms.
The words tumor and nodule are sometimes used inter-
changeably, which has caused confusion. Tumors can be
elevated from the skin and located entirely in the epi-
dermis, or they can be space-occupying lesions in the
dermis or subcutaneous tissue. Tumors often develop
necrosis over time because of their neoplastic nature. A
classic example of a skin tumor is a fungating tumor, as
seen with mycosis fungoides.
Hives or wheals are also known as urticaria; this is a
very specific term used to describe evanescent, pink-
red, pruritic plaques that spontaneously develop and
remit within 24 hours. They tend to be extremely pru-
ritic. Dermatographism is commonly seen in associa-
tion with hives. Vitiligo. Depigmented macules
Blistering disorders are common pathological condi-
tions, and their lesions may be described as vesicles or
bullae. A vesicle is defined as a fluid-filled elevation less
than 1 cm in diameter. A bulla is a fluid-filled epidermal
cavity larger than 1 cm in diameter. Blisters are most
often filled with serous fluid, but they can be filled with
a purulent exudate or a hemorrhagic infiltrate. Bullae
are often described as flaccid or as firm and intact.
Pustules are small elevations in the epidermis that are
filled with neutrophilic debris. The infiltrate within a
pustule may be sterile or infectious in nature. An
example of a sterile pustule is pustular psoriasis. An
example of an infectious pustule is folliculitis.
Secondary lesions are often encountered in the der-
matology clinic and are of utmost importance when
describing skin lesions and rashes. The word scale is
used to describe exfoliating keratinocytes that have
typically built up in such a mass that there is obvious
surface change to the skin. Normal shedding of kerati-
nocytes occurs on a daily basis, so a small amount of
scale is found on every human’s skin. It is the collection
in large quantities that allows one to use scale as a
descriptive term. Scale must be differentiated from
crust. Crust is produced by the drying of blood, serum,
or purulent drainage. Most commonly, a crust is
described as a scab.
Excoriations are secondary lesions that develop as a
result of repetitive scratching. Excoriations are typically Tinea faciei. Annular scaly patches Herpes simplex virus. Tender
vesiculo-pustules on a red base
linear but can be seen in many bizarre configurations. with a leading edge of scale
Erosions are seen in many skin disorders, most
commonly superficial blistering diseases, in which the
upper layers of the epidermis have been removed,
leaving a shallow, denuded erosion. Erosions are
defined as breaks in the epidermis. This is in contrast Scar is another secondary descriptive term used to and thickened from the chronic rubbing. A classic
to ulceration, which is defined as a break in the skin describe the healing of the epidermis and dermis, example of lichenification is lichen simplex complex.
that extends into the dermis or subcutaneous tissue or, usually in a linear or a geographic pattern, caused by The last of the secondary descriptive lesions dis-
in severe cases, muscular tissue. A fissure is often seen some form of trauma or end-stage inflammatory cussed here are burrows. Burrows are seen as tiny,
on the palms or soles; it is a full-thickness epidermal process. Fresh scars are typically pink to red; over time, irregularly shaped, serpiginous or linear scale, often
break that follows the skin lines. Fissures have very they mature, becoming flattened and more pale. with a tiny black dot at one end. They are pathogno-
sharply defined borders and are typically only a few Lichenification is seen as an end process in chroni- monic for the diagnosis of scabies, and the tiny black
centimeters long. cally rubbed skin. The skin lines become accentuated dot represents the scabies mite.

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 11