Page 1444 - Clinical Small Animal Internal Medicine

1382 Section 12 Skin and Ear Diseases

solely on the area(s) that the owner mentions or you may is critical in refining the list of differentials. Also, know-
VetBooks.ir miss hidden, subtle lesions that can offer important diag- ing how primary lesions typically evolve into secondary
lesions gives the clinician a better understanding of dis-
nostic clues pertaining to the underlying disease process.
A well‐lit room is essential and a hand‐held magnifying
ously and is a reflection of the underlying disease process;
lens may be useful for close examination of lesions. In ease progression. A primary lesion develops spontane-
some instances, the hair may need to be clipped to thus these lesions are the most important to identify.
allow for proper visualization. Painful or “uncoopera- Secondary lesions evolve from primary lesions or are
tive” patients may require sedation. created by the patient scratching or external forces such
Many dermatologists prefer to start with the nose and as trauma, medications, and infection of primary lesions.
head region and work caudally, including all accompany- Some lesions can be considered primary or secondary.
ing mucosal and mucocutaneous surfaces. The interdigi- Table 157.2 provides a list and description of basic cuta-
tal spaces, claws, ungual folds, and pawpads must always neous lesion morphology. An accompanying figure is
be evaluated with the patient either standing or in lateral provided for most of these lesions which elaborates on
recumbency. Part the hair or roll the skin into individual their significance/pathomechanism and provides exam-
folds to separate the hair and allow for easier evaluation ples of differentials (Figures 157.1–157.18).
of the cutaneous surface and follicular ostia while also
noting the haircoat quality, color, and luster. Throughout
the evaluation, look for evidence of pruritus, such as Table 157.2 Terminology used to describe lesion morphology
excoriations and salivary staining, the latter of which
commonly manifests as a brownish‐red discoloration of Lesion Definition
the haircoat. An otoscopic examination should be per-
formed in all patients. Examination findings can be doc- Primary lesions
umented using topography maps available at www.vin. Macule/patch Circumscribed, flat, nonpalpable
com or in the texts listed in the Further Reading section. (see Figure 157.1) change in skin color <1 cm. If larger,
These maps allow for quick illustration of lesion distribu- termed a patch
tion and character during the initial consultation and subse- Papule/plaque Solid elevation of skin ≤1 cm in
quent rechecks which assist the clinician in making (see Figure 157.2) diameter. Plaque formed by confluence
comparisons regarding disease progression between of papules >1 cm in diameter. Can be
appointments. The patient should be auscultated, and follicular or nonfollicular
the lymph nodes and abdomen palpated. These aspects of Vesicle/bulla Circumscribed, elevated skin lesion
a general examination are important as they can reveal (see Figure 157.3) containing fluid ≤1 cm in diameter. If
greater than 1 cm, termed a bulla. Can
an underlying systemic disease which may be giving rise be intraepidermal or subepidermal
to the dermatologic changes. Also, findings on a general Pustule A vesicle containing purulent exudate.
PE may dictate or change the choice of drug therapy. For (see Figure 157.4) Can be follicular or nonfollicular
instance, the discovery of a cardiac murmur in a feline Wheals Flat‐topped sharply circumscribed
patient may prompt the clinician to be more cautious (see Figure 157.5) elevation of the skin caused by edema.
with the administration of injectable glucocorticoids, If regionalized or generalized, referred
given that cats are at increased risk of developing con- to as angioedema
gestive heart failure when receiving them, especially Nodule/tumor Solid or cystic elevation of skin >1 cm
methylprednisolone acetate. (see Figure 157.6) in diameter. Tumor if >2 cm in diameter
During the course of the PE, the clinician must learn to Secondary lesions
identify the major features of the skin lesions. This will Epidermal collarette Circular lesion with a rim of loosely
allow the disease to be placed in diagnostic categories (see Figure 157.7) adhered scale or peeling keratin. Often
that facilitate diagnosis. Most important are the type of described as the "footprint" of a
lesions (primary or secondary) and lesion distribution pustule or vesicle
(body sites involved). Proper identification of lesions is Excoriation Superficial excavations of the epidermis
crucial, as they can be correlated with specific diseases. (see Figure 157.8) that may be linear or punctate
Erosion/ulceration Superficial epidermal defect that heals
(see Figure 157.9) without scarring due to trauma or
Morphology of Lesions inflammation. If deep enough to affect
the dermis, an ulcer occurs and heals
Lesion morphology refers to the categorization of cuta- with scarring
neous lesions as primary, secondary, or either primary or Scar Formation of fibrous tissue in place of
secondary. The ability to accurately identify these lesions damaged dermis or subcutaneous
as well as having an understanding of their development tissue