A 24-year-old man presented with long-standing cough and occasional hemoptysis. Endoscopy demonstrated a 2 cm, polypoid tracheal mass. An endoscopic excision was performed resulting in the specimen seen below.
The specimen consists of nests and sheets of bland, uniform polygonal cells in a prominently vascular stroma. Mitotic figures are extremely rare and there is no evidence of necrosis. Clinically, and on initial pathologic examination this was thought to be a typical carcinoid tumor (well-differentiated neuroendocrine carcinoma). However, immunohistochemical stains for neuroendocrine differentiation were all negative.
What is your diagnosis?
The case was submitted in consultation and the features above were noted by us as well. In addition, it was noted that many of the cells had perinuclear halos creating a "fried egg" appearance and that these cells often cuffed around more dialated vascular spaces. Stains for cytokeratin and repeat stains for neuroendocrine markers were negative. A immunohistochemical stain for smooth muscle actin (SMA) is shown below.
This is a nice example of a glomangiopericytoma or glomus tumor. I generally prefer the former, longer term because some clinicians still confuse "glomus tumor" with paraganglioma, particularly in the head and neck region. However, the newer term has yet to be fully accepted, so it's your choice which term to use, and I'll use both, even in this brief text. The skin of the extremities is by far the most common site for glomus tumors, where they represent the "G" in the "ANGEL" of painful cutaneous lesions. However, they can occur sporadically at almost any location. These tumors are composed of cells differentiating towards (who knows if they actually originate from) the specialized pericytes that control blood shunting for temperature regulation. They are virtually always benign, although in some anatomic locations such as the sinonasal region they can be somewhat difficult to remove. Glomus tumors of the trachea are quite rare but a quick search with PubMed or Google will turn up multiple examples, usually in the form of single case reports.