CHAPTER 38 PANNICULITIS 565
Cutaneous Neoplasia
Lipomas: soft; usually well demarcated.
No inflammation or draining tracts.
Aspirates: lipocytes; no inflammatory cells.
Biopsies: confirm diagnosis.
Mast Cell Tumors/Cutaneous Lymphosarcoma/Pancreatic Panniculitis
Multifocal.
May affect the head, legs, and mucous membranes.
Often erythematous.
Variable presentations.
Aspirates: often suggestive.
Biopsies: confirm diagnosis.
Sterile Nodular Panniculitis
Diagnosis made by ruling out other causes of panniculitis.
Tissue cultures negative.
Special stains on histopathologic samples are negative.
DIAGNOSTICS
Occasional regenerative left shift or eosinophilia.
Mild leukocytosis.
Mild normochromic, normocytic nonregenerative anemia.
Antinuclear antibody.
Direct immunofluorescence testing.
Serum protein electrophoresis.
Serum lipase/amylase levels.
Ultrasound: pancreatitis may be a contributing factor (rare).
Bacterial culture and sensitivity testing: necessary for identifying primary or sec-
ondary bacteria.
Fungal and atypical mycobacteria culture.
Aspirates from fluctuant nodules may appear oily, with examination revealing large
numbers of adipocytes in addition to pyogranulomatous inflammation (Figures 38.9,
38.10).Biopsies: negative tissue cultures support diagnosis of sterile nodular panniculitis.
Histopathology divided into four forms: nodular inflammatory aggregates, lobular
(within fat lobules), septal (interlobular connective tissue), and diffuse (involves both
lobular and interlobular septa).Diffuse form most common in dogs.
Septal form most common in cats.