Page 1507 - Clinical Small Animal Internal Medicine

164 Canine Sterile Papular and Nodular Skin Diseases 1445

Clinical Signs systemic signs reported include peripheral lymphade-
VetBooks.ir Clinically, SNP manifests as single or multiple subcu- nopathy, joint effusion and pain, vomiting, and abdomi-
nal pain.
taneous nodules varying in size from a few millimeters
to several centimeters in diameter. Lesions can be of
normal skin color or be erythematous or bluish in Diagnosis
color. Initially, the nodules are firm but they may liq- Sterile nodular panniculitis must be differentiated from
uefy and become soft. Some lesions regress while oth- other forms of panniculitis and other diseases with simi-
ers develop draining tracts and become ulcerated lar clinical presentation, including infectious diseases
(Figure 164.3). such as bacterial, fungal or mycobacterial infection, ster-
Well‐delineated ulcers are characteristic. Draining
lesions discharge an oily, clear to yellowish brown mate- ile granuloma and pyogranuloma syndrome, foreign
bodies, injection site reaction, insect bite, drug reaction,
rial, which may also be hemorrhagic (Figure 164.4). and neoplasia. Sterile nodular panniculitis is diagnosed
Nodules may heal with scarring and are more com-
monly found on the trunk but can occur anywhere. based on the patient’s history and clinical signs, exclu-
sion of other causes of panniculitis, and cytologic and
Fever, lethargy, and anorexia are commonly seen in dogs histopathologic findings. It can be a cutaneous marker of
with multiple lesions; these signs occur simultaneously a concurrent disease process so a systematic diagnostic
or just before the beginning of nodule formation. Other
approach is needed to help identify a possible etiologic
factor.
A complete history, physical examination, and mini-
mum database including hemogram, chemistry profile
and urinalysis can serve as guides in deciding which
additional test(s) will be useful in the diagnosis. In a
recent study, neutrophilia, increased alkaline phos-
phatase (ALP), mild hypoglycemia, and hypoalbumine-
mia were present in over 50% of cases with systemic
involvement. Cytologic evaluation of aspirates from
intact lesions can vary in appearance from suppurative
to pyogranulomatous or granulomatous with fat droplets
or cells present and no microorganisms. Aspirates from
deep firm nodules may show spindle cells that resemble
neoplastic cells. The definitive diagnosis can be based
only on histopathologic findings. Wedge biopsies should
be performed to collect samples that include the epider-
mis, dermis, and subcutaneous tissue. The sample should
Figure 164.3 Multifocal areas of ulceration on the lateral thorax of
a Labrador retriever with sterile nodular panniculitis. be collected aseptically if submitted for fungal, bacterial
(aerobic/anaerobic), and mycobacteria cultures. Bacterial
and fungal cultures of intact nodules yield no growth.
Special stains of biopsy samples can be used to help elim-
inate bacteria and fungi as causative agents. Some organ-
isms are difficult to culture or identify with routine
methods, and molecular studies like polymerase chain
reaction (PCR) are necessary. This is particularly true for
mycobacteria and Leishmania.

Therapy
Surgical excision of solitary masses can be curative. Dogs
with multiple lesions are treated with immunosuppres-
sive drugs. In dogs, oral prednisone or prednisolone is
usually effective at 2 mg/kg/day for two weeks; then, the
patient should be reevaluated. If remission is achieved
Figure 164.4 Oily, hemorrhagic discharge from an ulcerated
nodule in a Weimaraner with sterile nodular panniculitis. within that time, the dose should be decreased by 25%
Source: Courtesy of Dr Melanie Hnot. every seven days until the lowest effective dose is given