022. Granular cell tumor of the lung

Background: Granular cell tumor, also known as granular cell myoblastoma, is an uncommon benign tumor with female predisposition, that involves any part of the oral cavity, but the tongue is the most common site. It is considered to be of mesenchymal origin (myoblastic), but at present, the tumor is believed to derive from Schwann cells, and the granularity of the cytoplasm may be associated with accumulation of lysosomes. Cases of granular cell tumors of the lung/ tracheobronchial tree are extremely rare (6-10% of all the granular cell tumors, 0.2% of the lung neoplasms).

Methods: Three cases of granular cell tumor of the lung could be retrieved from files of the Department of Pathology of the “G. Papanicolaou” General Hospital, Thessaloniki at the period 1994-2014. Two of the patients were men of the 5^th decade of life and the third case was about a woman, 52-year-old, with multiple small bilateral intrabronchial tumors. The patients presented with slight chest pain, shortness of breath and cough. An excision biopsy via bronchoscopy was performed in all of them.

Results: Microscopically, the lesions were composed of large polygonal eosinophilic cells with highly granular cytoplasm and indistinct cell membranes, with ill-defined growth pattern. Immunohistochemically, the tumor cells were positive for S-100 protein. Ki 67 was practically zero. The lesions were pathologically diagnosed as granular cell tumors. There are no recurrences after removal.

Conclusions: Lung/tracheobronchial tree is an uncommon site for granular cell tumor, with the tongue being the classical location. In about 10-20% of the patients, the lesions are multiple. Congenital examples have been reported and others have systematic involvement. It is benign, rarely recurs, but occasional lesions with malignant behavior have been described. Granular cell tumor of the tracheobronchial tree usually can be easily excised via bronchoscopy, but when it involves submucosal glands, nerves or peribronchial tissues, should need surgical excision.

Keywords: Lung cancer; bronchoscopy; forceps