A rare case of bronchial glomus tumour of uncertain malignant potential

Introduction: Glomus tumours are typically benign pericytic mesenchymal neoplasms, occurring in the soft tissues of distal extremities, and rarely seen in deep soft tissues and visceral locations. Malignant glomus tumours are exceedingly uncommon. Here, we present a rare case of glomus tumour with uncertain malignant potential, arising in the bronchus of a young female patient. This case report highlights the clinical, radiological, and pathological aspects of this unusual entity, discussing the challenges in diagnosis and management and reviewing relevant literature on its behavior and treatment options. Case Presentation: A 35-year-old lady with progressive breathlessness and cough, was found to have an obstructive mass lesion in the right upper lobe bronchus on CT scan. Check bronchoscopy and biopsy revealed features of a low-grade spindle cell lesion, with the possible differentials of a Glomus tumour and low-grade myofibroblastic tumour. She underwent right upper lobectomy; the final histopathological exam with the aid of immunohistochemistry confirmed the diagnosis of a Glomus tumour of uncertain malignant potential. Post-operatively, due to localised disease with negative surgical margins, she was kept on regular follow-up and was asymptomatic 6 months post-surgery. Discussion: The possibility of a Glomus tumour must be considered for tumours with plump spindle to round cell morphology on a bronchoscopic biopsy. Immunohistochemistry helps to exclude most differentials. The assessment of malignant potential in Glomus tumour requires thorough examination of a completely resected tumour sample. Molecular studies have shown NOTCH1 gene rearrangements in both benign and malignant Glomus tumours. However, it does not help to predict malignant potential in benign-appearing tumours. Conclusion: Bronchial Glomus tumours of uncertain malignant potential are rare tumours requiring more research on molecular markers for prognostication and treatment. This case is presented for its rarity, diagnostic and prognostic challenges.