History

A 9-year-old spayed female domestic shorthair cat was evaluated because of nasal discharge and blood from the right nostril as well as progressive swelling of the bridge of the nose of 2 weeks' duration. At a previous examination performed 1.5 months earlier, the cat had appeared normal. A test for circulating FeLV antigen and anti-FIV antibody was performed 3 years prior to this evaluation, and results were negative; no follow-up testing had been done.

Clinical Findings

At the evaluation, the cat was bright, alert, and responsive. Body condition was considered good. Abnormal physical examination findings included firm facial swelling, which was most prominent between the eyes, and deviation of the nasal planum toward the left (Figure 1). Mucosanguineous nasal discharge was evident from the right nostril and, during handling, gray mucoid discharge was expelled from the left nostril. No other important abnormalities were detected on physical examination.

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Photograph of a 9-year-old spayed female domestic shorthair cat that was evaluated because of nasal discharge and blood from the right nostril and progressive swelling of the bridge of the nose of 2 weeks' duration. Notice the deviation of the nasal planum to the left.

Citation: Journal of the American Veterinary Medical Association 240, 6; 10.2460/javma.240.6.677

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Formulate differential diagnoses from the history, clinical findings, and Figure 1—then turn the page →

Cytologic Findings

Samples of the gray mucoid nasal discharge and 2 fine-needle aspirates of the facial swelling were collected, spread onto slides, and submitted for microscopic examination. All slides were routinely stained with aqueous Romanowsky stain.

Cytologic examination of the nasal discharge samples revealed evidence of septic suppurative inflammation. There were marked numbers of degenerate neutrophils with a few intracellular bacterial rods; bacteria were also present in extracellular locations (Figure 2). The background contained eosinophilic mucus strands. The fine-needle aspirate samples were composed of a monomorphic population of individually oriented round cells with high nuclear-to-cytoplasmic ratios in a background of peripheral blood and lymphoglandular bodies. The round cells were approximately 20 to 25 μm in diameter with oval to irregular nuclei that contained dispersed chromatin and prominent large (and occasionally multiple) nucleoli. The cytoplasm of the round cells was scant to moderate and basophilic with variable numbers of small distinct vacuoles. Rare binucleated cells and mitotic figures were present. Low numbers of vacuolated macrophages were visible with occasional erythrophagocytosis. The fine-needle aspirate findings were suggestive of a round cell neoplasm rather than a carcinoma, in which cells would be seen in cohesive clusters. The morphology of the round cells was consistent with lymphoid origin.

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Photomicrograph of a sample of the nasal discharge (A) and a fine-needle aspirate sample of the nasal swelling (B) of the cat in Figure 1. In the nasal discharge sample, there are numerous degenerate neutrophils. Aqueous Romanowsky stain; bar = 10 μm. In the fine-needle aspirate sample, notice the large individually oriented round cells (lymphocytes) with large prominent nucleoli (arrows) and scant to moderate basophilic cytoplasm with small distinct vacuoles. The cells are much larger than the neutrophils (arrowhead). Aqueous Romanowsky stain; bar = 10 μm. Inset in panel B—Note the 2 mitotic figures (top and center) and an intact lymphocyte (bottom). Aqueous Romanowsky stain; bar = 10 μm.

Citation: Journal of the American Veterinary Medical Association 240, 6; 10.2460/javma.240.6.677

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Gross and Histopathologic Findings

The owners requested euthanasia of the cat, and a necropsy was performed. Gross examination revealed a firm mass (1.5 × 1 × 0.5 cm) at the level of the eyes overlying the frontal bone. The skull was sagittally sectioned, and the architecture of the frontal sinus, nasal cavity, and associated subcutaneous tissues was effaced by an infiltrative, poorly demarcated, tan, and slightly firm neoplasm. Osteolysis of the frontal bone was evident, and neoplastic tissue extended into and expanded the overlying subcutaneous tissue. Within the renal cortex and extending into the renal medulla of the right kidney, there was a 1 × 1 × 1-cm, firm, tan neoplastic mass, which on cut section was unencapsulated but well demarcated.

Nasal cavity and renal tissues were routinely processed and stained with H&E stain for histologic examination. The cranial mass was an unencapsulated, invasive, highly cellular round cell neoplasm within the subcutaneous tissues, bones, and musculature that also effaced the nasal cavity (Figure 3). The neoplastic cells were arranged in sheets and supported by a fine fibrovascular stroma. The neoplastic cells were round with distinct cell margins and had a high nuclear-to-cytoplasmic ratio with scant eosinophilic cytoplasm; the nuclei were round with stippled chromatin and 1 to 2 prominent nucleoli. Epitheliotropism was not present. There were 10 mitotic figures in 10 randomly selected high-power (400×) fields. The epidermis in the region of the mass was severely ulcerated with moderate numbers of neutrophils; neutrophils were also present in the lumen of the nasal cavity along with necrotic debris and myriad bacteria. Immunohistochemical staining was performed on sections of the nasal tumor to evaluate for expression of CD3 and CD79a. Most of the neoplastic cells had strong cytoplasmic expression of CD79a; only scattered CD3-positive cells were detected. Neoplastic cells within the right kidney were similar to those of the nasal mass.

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Photomicrograph of a section of the nasal mass in the cat in Figure 1. Notice the sheet of neoplastic lymphocytes underlying the nasal mucosa (asterisk) and the luminal necrotic debris with degenerate neutrophils (arrow). H&E stain; bar = 200 μm.

Citation: Journal of the American Veterinary Medical Association 240, 6; 10.2460/javma.240.6.677

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Morphologic Diagnosis

Nonepitheliotropic B-cell lymphoma of the nasal cavity with associated suppurative rhinitis and epidermal ulceration and lymphoma of the right kidney.

Comments

Chronic nasal discharge is a nonspecific clinical finding that is often associated with a variety of nasal diseases, including allergic and infectious (viral, bacterial, or fungal) rhinitis, foreign body, nasal polyp, trauma, dental disease, and neoplasia. Neoplasia is a common cause of chronic nasal discharge in cats, particularly when dyspnea or unilateral or bloody nasal discharge is present.^1–3 Although facial swelling and deformity are not specific clinical findings of neoplasia of the nasal cavity, these abnormalities commonly develop in affected cats. Other causes of facial swelling and deformity include rhinitis, foreign bodies, polyps, and fungal infections.¹

Diagnosis of the underlying cause of chronic nasal discharge and facial deformity relies on a combination of results of cytologic, histologic, radiographic, rhinoscopic, and computed tomographic examinations and bacterial and fungal cultures of tissue or discharge samples.¹ For patients with chronic nasal discharge, cytologic examination is often the initial diagnostic step because it is minimally invasive and typically does not require sedation or anesthesia and the results are rapidly available. To provide accurate and useful information, samples collected for cytologic examination must be both cellular and representative of the lesion or disease process; therefore, selection of an appropriate sample is crucial. Samples for cytologic examination may include nasal discharge, flushes or swab specimens of the nasal cavity, fine-needle tissue aspirates of lesions, or impression smears from nasal biopsy specimens.⁴ As illustrated by the case of this report, nasal discharge samples (which are easy to collect) often yield only superficial inflammatory cells and bacteria and cytologic examination of such samples is often of limited value. Samples obtained by flushing or swabbing the nasal cavity often have the same diagnostic limitations as those of samples of nasal discharge. For pathological conditions involving deeper tissues, samples collected by these methods are often not adequate, and neoplasia may be misdiagnosed as rhinitis if the diagnosis is made solely on the basis of findings of examination of superficial samples. More aggressive collection of samples of the nasal cavity via fine-needle aspiration typically results in a more representative sample of deeper tissue, which usually is needed for the diagnosis of nasal neoplasia. Fine-needle aspirates are strongly recommended whenever a well-defined swelling or lesion is identified during physical examination or diagnostic imaging. In the cat of this report, examination of fine-needle aspirate samples of the nasal swelling resulted in a definitive diagnosis of lymphoma. The fine-needle aspirate samples were highly cellular and had a substantially different population of cells, compared with the cells detected in the nasal discharge samples. The nasal discharge was reflective only of exudate and not representative of the neoplastic process. In some cases, even fine-needle aspirate samples obtained directly from a mass may not yield representative cells. If fine-needle aspiration fails to reveal atypical cells when neoplasia is strongly suspected on the basis of clinical findings, histologic examination of biopsy specimens may be required to obtain a diagnosis.

Various types of neoplasia in the nasal cavity of cats have been reported. Lymphoma and epithelial tumors (carcinoma, adenocarcinoma, and squamous cell carcinoma) are the most common,³ with no clear consensus on which type is more frequent. Other less common neoplasms include sarcomas (fibrosarcoma, osteosarcoma, and chondrosarcoma), mast cell tumors, melanomas, plasmacytomas, olfactory neuroblastomas, and benign lesions (hemagioma, chrondroma, and neurofibroma).³

The findings of the microscopic examinations of the fine-needle aspirate samples and tissue sections from the cat of this report were consistent with lymphoma. Nasal lymphoma is most often of B-cell origin (as in this cat) and develops in older (9- to 12-year-old) FeLV-negative cats.^1,5,6 Tumors are locally invasive and associated with a low metastatic rate at the time of diagnosis; however, systemic extension has been reported and enlarged regional lymph nodes should be evaluated.⁶ For cats with nasal lymphoma, treatment involves administration of chemotherapeutic agents or radiation therapy. Among cats with extranodal lymphoma, those with nasal lymphoma in complete remission appeared to have the longest survival times.⁷ Radiation therapy has been used effectively to treat nasal lymphoma in cats, and complete remission is common.⁶

As indicated by the case reported here, it is important to select appropriate samples for reliable cytologic examination and diagnosis of nasal lymphoma. The submission of superficial samples may not reveal underlying pathological changes, and fine-needle aspiration of lesions is strongly recommended whenever possible. For the cat of this report, results of cytologic examination of fine-needle aspirate samples were sufficient to establish a diagnosis of nasal lymphoma, whereas similar evaluation of nasal discharge samples alone could have been misleading.