Sterile pyogranulomatous nodular dermatitis

46 Sterile pyogranulomatous nodular dermatitis


Pyrexia, pain and a reluctance to move may be evident on physical examination. Single or multiple nodules are normally located on the trunk or on the neck. Nodules present deep within the subcutis would suggest a panniculitis. They may vary in size, ranging from a few millimetres to several centimetres in diameter. The nodules may be well demarcated or ill defined, and on palpation they may appear either soft and/or fluctuant, or hard. Some cases may have draining tracts that release a purulent or even oily exudate (in the case of panniculitis) of variable colour.

In this case:


It is essential to systematically and carefully rule out all the other differential diagnoses in order to make a diagnosis of idiopathic sterile pyogranulomatous dermatitis. In any nodular disease, cytological examination of fine-needle aspirates and/or impression smears of exudate is indicated. A pyogranulomatous inflammation (neutrophils and macrophages) and an absence of microorganisms will be seen in cases of sterile pyogranulomatous disease. Biopsied specimens are essential for bacterial and fungal cultures, and also for histology. Either an excision biopsy of a nodule or a wedge biopsy of a larger lesion should be taken for this purpose. Special staining techniques of histological sections can help to rule out the presence of bacterial and fungal organisms. Ziehl–Neelsen (ZN) stain may reveal acid-fast bacteria such as Mycobacteria and Nocardia. Other bacteria may be identified by their Gram-staining properties. Periodic acid–Schiff (PAS) stain and Gomori’s silver stain are used to identify the presence of fungal elements.

As nodular skin disease is sometimes associated with systemic conditions, haematology and biochemistry, including serum amylase and pancreatic-specific lipase, are indicated, especially if gastrointestinal signs or abdominal signs are present. If pancreatic disease is suspected, abdominal ultrasonography and radiography, followed by exploratory surgery, may be necessary.

In this case the following tests were performed:

Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Sterile pyogranulomatous nodular dermatitis
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