A challenging case: Painful periocular swelling in a cat - Veterinary Medicine
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A challenging case: Painful periocular swelling in a cat
An ophthalmic examination provides valuable clues for diagnosing an uncommon disorder with mostly nonspecific signs.



Differential diagnoses for bilateral ocular and orbital disease in this case included infectious causes such as systemic fungal disease (cryptococcosis, aspergillosis, blastomycosis, penicilliosis, histoplasmosis)1-9 or aerobic or anaerobic bacteria,10,11 neoplastic processes (lymphosarcoma, squamous cell carcinoma, osteoma, osteosarcoma, fibrosarcoma),10,12,13 and primary inflammatory disorders (eosinophilic, pseudotumor).11,14,15


Because of the patient's fractious nature, the cat was placed under general anesthesia and intubated to allow maintenance of anesthesia with isoflurane while a complete blood count (CBC), a serum chemistry profile, thoracic radiography, and orbital and ocular ultrasonography and aspiration were performed. A temporary tarsorrhaphy of the left eye was also performed to provide corneal protection.

CBC and serum chemistry profile

The only significant abnormalities noted were hyperproteinemia (8.2 g/dl; reference range = 6 to 7.5 g/dl) and a mild mature neutrophilia (15.4 x 103/l; reference range = 2.5 to 12.5 x 103/l), which were both attributed to inflammation.

Thoracic radiography

Thoracic radiography showed a pneumomediastinum with extension into the retroperitoneum, likely induced by barotrauma. Barotrauma most commonly occurs as a complication of mechanical ventilation and results in extra-alveolar air accumulation.

On follow-up radiography, no pulmonary parenchymal abnormalities were found, the pneumomediastinum had resolved, and thoracic radiography results were considered normal.


2. A dorsal oblique plane ultrasonographic image of the left globe showing a diffusely thickened and completely detached retina.
Ocular ultrasonography confirmed a partial retinal detachment in the right eye. A diffusely thickened and completely detached retina was identified in the left eye (Figure 2).

3. A dorsal plane ultrasonographic image of the homogenous left retrobulbar mass displacing the sclera.
Orbital ultrasonography results showed a homogenous retrobulbar mass, measuring 2.2 x 1.5 cm, deforming the posterior sclera on the left side (Figure 3). A similar but smaller (1.9 x 0.8 cm) homogenous mass was noted in the right orbit. Fine-needle aspiration of the left retrobulbar mass was performed for cytologic examination.


4. Cytologic examination findings from the fine-needle aspiration of the left retrobulbar mass seen in Figure 3. Note the macrophage with phagocytosed Histoplasma capsulatum yeast; rare, small, mature lymphocytes; and aggregates of erythrocytes (Diff-Quik—Dade Behring; bar = 20 m).
Moderate numbers of adequately preserved nucleated cells with mild-to-moderate blood contamination were noted (Figure 4). Moderate numbers of small, mature lymphocytes; a few slightly vacuolated macrophages; and a few nondegenerate neutrophils were present. Low numbers of small (2 or 3 m long and 1 or 2 m wide), round-to-oval yeast were present both extracellularly and phagocytosed by the macrophages. These yeast were surrounded by a thin clear halo and contained a small, eccentrically located, crescent-shaped purple nucleus.

The cytologic interpretation was granulomatous inflammation with intracellular Histoplasma capsulatum organisms.


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