🔍 What Are Oncocytomas?

Oncocytomas are rare, typically benign tumors composed of oncocytes—cells filled with abundant mitochondria, giving them granular, eosinophilic cytoplasm :contentReference[oaicite:3]{index=3}. In cats they’ve been found in endocrine-related sites: salivary glands, kidney, nasal cavity, and even the brain's choroid plexus :contentReference[oaicite:4]{index=4}.

1. Where They Occur

• Mandibular & parotid salivary glands: solitary, slow-growing masses beneath the jaw or near the ear canal :contentReference[oaicite:5]{index=5}.
• Kidney: renal oncocytomas, though rare, appear as incidental ultrasound-detected masses and may mimic carcinomas :contentReference[oaicite:6]{index=6}.
• Nasal cavity: nasal oncocytoma documented in an older Siamese cat :contentReference[oaicite:7]{index=7}.
• Choroid plexus (brain): extremely rare intracranial oncocytoma reported :contentReference[oaicite:8]{index=8}.

2. Who’s Affected?

• Usually older cats (median age ~9–15 years).
• No clear sex or breed predisposition—seen across domestic shorthairs and Siamese.
• Occurs in sites harboring epithelial or endocrine tissue.

3. Clinical Signs by Location

• Salivary gland: slow-growing firm mass under jaw; may cause discomfort swallowing or grooming.
• Renal: often asymptomatic; possible weight loss, blood in urine or abdominal mass :contentReference[oaicite:9]{index=9}.
• Nasal: nasal discharge, obstruction, sneezing, face swelling :contentReference[oaicite:10]{index=10}.
• Brain: neurological deficits like ataxia or seizures, depending on brain region involved :contentReference[oaicite:11]{index=11}.

4. Why They Develop

The cause is unknown, though oncocyte formation is thought driven by mitochondrial proliferation in epithelial cell lines :contentReference[oaicite:12]{index=12}. These tumors remain benign, although occasional local invasion and very rare recurrence have been noted :contentReference[oaicite:13]{index=13}.

5. Diagnostic Workflow

1. History & physical exam: check mass size, mobility, and location-specific symptoms.
2. Imaging:
   • Ultrasound for kidney or salivary masses;
   • CT/MRI for nasal or brain cases;
   • Radiographs for chest metastasis exclusion.
3. Sampling: FNA or core biopsy. Oncocytomas display clusters of eosinophilic granular cells with round nuclei :contentReference[oaicite:14]{index=14}.
4. Histopathology: confirms oncocytoma via typical large oncocytes and absence of malignancy; immunohistochemistry aids differentiation from carcinoma :contentReference[oaicite:15]{index=15}.

6. Treatment Approaches

a. Surgical Resection

• Salivary or nasal tumors: local excision usually curative; mandibular mass removal showed excellent long-term outcome :contentReference[oaicite:16]{index=16}.
• Renal tumors: nephrectomy appropriate for solitary masses; cats tolerate kidney removal well :contentReference[oaicite:17]{index=17}.
• Brain lesions: surgical removal of choroid plexus oncocytomas achievable :contentReference[oaicite:18]{index=18}.

b. Adjunctive Therapies

• Radiation: considered if complete excision isn’t feasible (nasal, intracranial).
• Medical management: pain control, supportive care for incompletely excised tumors.

7. Prognosis

• Oncocytomas are generally benign and cured by complete removal.
• Long-term survival documented: >17 months for parotid gland case :contentReference[oaicite:19]{index=19}; several years in renal cases :contentReference[oaicite:20]{index=20}.
• Malignancy risk is very low—but incomplete excision may lead to local recurrence :contentReference[oaicite:21]{index=21}.

8. Follow-Up & Monitoring

• Recheck every 3–6 months with exam and site imaging.
• Periodic ultrasound or MRI for internal tumors.
• Monitor for regrowth or signs of local invasion.

9. Ask A Vet Remote Monitoring 🐾📲

• 📸 Upload photos of masses—track size, appearance, or healing post-surgery.
• 🔔 Receive reminders for medication or vet appointments.
• 🧭 Log appetite, activity, wound changes, or breathing difficulty.
• 📊 Alerts if masses regrow, symptoms recur, or wound healing stalls.
• 👥 Virtual follow-ups to guide further diagnostics or intervention planning.

10. FAQs

Are oncocytomas cancer?

No—they’re benign tumors. Although rare recurrence can happen, wide surgical margins are typically curative.

Could it spread?

Metastasis is extremely unlikely—but local invasion is possible if incomplete excision occurs.

Do cats live well with one kidney removed?

Yes—cats tolerate nephrectomy very well, with minimal long-term complications.

Is radiation needed?

Only if tumors are in locations where surgery isn’t fully curative (e.g., nasal, brain).

11. Key Take‑Home Tips ✅

• Early evaluation: investigate any persistent masses under jaw, in mouth, kidney, nose, or brain symptoms.
• Imaged and sampled: imaging + biopsy critical to rule out malignant tumors.
• Resection is best: surgical removal offers high likelihood of cure.
• Monitor post-op: routine follow-up with exam and imaging.
• Remote support: Ask A Vet assists with monitoring, surgery planning, and ongoing surveillance.

Conclusion

Feline oncocytomas are rare, usually benign tumors arising in glandular tissue—salivary, renal, nasal, or intracranial. With thorough imaging, biopsy, and surgical removal, outcomes are excellent and long-term survival is expected. Remote care support via Ask A Vet streamlines monitoring, enhances compliance, and provides around‑the‑clock reassurance through 2025 and beyond 🐾📲.

If your cat develops a firm mass under the jaw, abdominal signs linked to kidney disease, nasal discharge, or neurological symptoms—seek veterinary consultation and start Ask A Vet monitoring for personalized guidance and peace of mind.