INTRODUCTION: Oncocytoma is an uncommon tumor of epithelial origin. It is characteristically composed of large eosinophilic cells with small round nuclei and large nucleoli. They commonly occur in the kidney, salivary glands, and thyroid. Their occurrence in the lungs is extremely rare with less than 10 cases reported in the literature. We are reporting a case of 26 years-old man with persistent pulmonary infiltrates found to have pulmonary oncocytoma.
CASE PRESENTATION: A 26 year old nonsmoker male with a past medical history of depression, sinusitis, and hepatitis C infection with undetectable viral load, was initially referred to the chest clinic for a + PPD and an right mid lung filed infiltrate on chest x-ray. He complained of brownish sputum with blood tinged at the time for about two days. He denied any constitutional symptoms. A chest CT scan showed an infiltrate in the superior segment of his right lower lobe that was treated with a 14 day course of a macrolide. Sputum AFB smear and cultures were negative. A repeat CT scan showed persistent infiltrates for which he underwent fiberoptic bronchoscopy and transbronchial biopsy which was nondiagnostic. After two years of lost follow up, he had a CT scan which showed a mass which was more confluent, and a PET scan which showed borderline neoplastic activity (SUV of 2.7). Repeat bronchoscopy and biopsy was diagnostic of bronchial oncocytic hyperplasia. Case was discussed in the chest multidisciplinary conference and patient was scheduled to undergo right lower lobe lobectomy.
DISCUSSIONS: Oncocytomas are uncommon tumors composed of mitochondria-rich oxyphilic cells called oncocytes. They are usually considered to be benign lesions. High grade tumors with metastases are occasionally seen in a small percentage of cases. They were first described in the salivary glands of man in 1897. Later, they were also found in glands of the tongue, pharynx, esophagus, and trachea, with the parotid and the submandibular gland being the most common sites. Oncocytomas also account for about 5% of kidney tumors. The characteristic feature of an oncocyte is its granular eosinophilic cytoplasm, which is due to mitochondrial hyperplasia. As hyperplasia of other cytoplasmic organelles can produce cytoplasmic eosinophilia. Some case are problematic in terms of making an accurate diagnosis, due mainly to the large number of differential diagnoses involving tumors, ranging from overtly malignant to clearly benign. Sometimes electromicroscopic study may be essential to confirm such diagnosis.Fewer than ten case reports of pulmonary oncocytomas have been reported to our knowledge in the literature. Most reported patients were relatively asymptomatic. They were found to have a mass on chest X-Ray. The diagnosis was reached only after excision in the majority of cases. To our knowledge there was one case report of a diagnosis being obtained by transbronchial biopsy. Oncocytomas are usually benign tumors. They should be considered in the differential diagnosis of mass lesions in the lung, making the appropriate diagnosis is imperative as adequate surgical excision is usually curative.
CONCLUSION: The importance of identifying pulmonary oncocytomas lies not only in ruling out a metastatic tumor but also because of its ability to mimic pulmonary tumors with diverse clinical outcomes. Adequate surgical excision is usually curative.
DISCLOSURE: Gerald Tarirah, No Financial Disclosure Information; No Product/Research Disclosure Information