D110-18 Out of Place: A Glomus Tumor in the Lung of a Young Woman

Background Pulmonary glomus tumors (GTs) are exceedingly rare mesenchymal neoplasms arising from modified smooth muscle cells of the glomus body, with approximately 50 cases reported in the literature. While typically benign and found in the extremities, their occurrence in the lung parenchyma is highly unusual and may mimic primary or metastatic malignancies radiographically and histologically. Case Presentation We report the case of a 37-year-old female, never-smoker, with a history of childhood asthma, who presented with a persistent cough unresponsive to outpatient antibiotic therapy. A chest X-ray revealed a right upper lobe mass, and subsequent CT imaging demonstrated a 5.7 × 3.6 × 6.5 cm heterogeneous lesion with central fluid components and no evidence of adenopathy or metastatic disease. Retrospective review of prior imaging identified the same lesion two years earlier on the scout view of a CT abdomen, suggesting an indolent process. PET scan demonstrated low-grade uptake, further lowering suspicion for malignancy. The patient underwent robotic right upper lobectomy after intraoperative findings rendered wedge resection unfeasible. Histopathological evaluation revealed a well-circumscribed spindle cell neoplasm composed of bland oval to elongated cells without mitotic activity. Immunohistochemical staining was positive for smooth muscle actin (SMA) and collagen IV but negative for pancytokeratin, ER, PR, MART-1, desmin, HMB-5, TTF-1, and S100, thus, confirming the diagnosis of a benign glomus tumor. The postoperative course was uneventful, and the patient was discharged on postoperative day three. Discussion Pulmonary glomus tumors are rare entities that can pose significant diagnostic challenges due to their nonspecific radiologic features and resemblance to more common neoplastic lesions. Most cases are benign and managed effectively with complete surgical excision. Although our patient’s tumor was relatively large, it demonstrated no histologic features of malignancy as defined by Folpe’s criteria. This case also highlights an important diagnostic pitfall—the lesion had been visible but overlooked on prior CT scout imaging, underscoring the value of carefully reviewing all available radiographic data. Conclusion This case underscores the importance of maintaining a broad differential diagnosis when evaluating lung masses, particularly in younger, low-risk patients. Pulmonary glomus tumors, while rare, should be considered among benign etiologies. Furthermore, clinicians and radiologists should not disregard CT scout views, as these may provide valuable diagnostic clues and prevent unnecessary patient anxiety or delay in diagnosis. This abstract is funded by: None