Pulmonary granular cell tumour presenting as an incidental endobronchial lesion in a child: a case report

Pulmonary granular cell tumour is a seldom-seen Schwann cell-derived lesion, particularly in children, and most frequently endobronchial in the case of the respiratory tract. A 12-year-old boy presented with cough, rhinorrhoea and mild breathlessness and imaging performed at another site revealed atelectasis of the right middle lobe. Bronchoscopy showed the right middle lobe bronchus narrowing, and an incidental whitish lobulated polypoid lesion at the genesis of the right upper lobe bronchus. Endobronchial biopsy was done and histopathology revealed bronchial mucosa was stretched by cells with great cytoplasmic granules and smooth nuclei. Positiveness of S100 and CD68 with negativity of cytokeratin, INSM1, p40 and smooth muscle actin on immunohistochemistry confirmed granular cell tumour. Although the lesion appeared relatively benign bronchoscopically, PET-CT was performed to further characterize the lesion and assess its metabolic activity and extent before management. Biopsy and bronchoalveolar lavage microbiological tests were negative to tuberculosis, fungal elements and bacterial growth. As indicated in this case, endobronchial granular cell tumour can be incidentally discovered during bronchoscopy and diagnosis requires histopathology with immunohistochemistry. The management should be personalised based on the symptoms, size of tumour, airway obstruction and follow-up results.