Patients can be seen where “fungal debris,” “mycetoma,” or “mass-like obstruction” of the sinonasal tract is suspected clinically but lack fungus and instead have granular, eosinophilic debris and bacterial colonies. We report and characterize 15 such cases, tentatively termed “bacteromas,” compared with randomly selected cases of mycetoma and allergic fungal sinusitis (AFS). Pathology reports from 2016 to 2021 were searched. All candidate cases were examined microscopically and included if they had granular, amorphous debris with negative Grocott methenamine silver staining and lacked diagnostic features of other entities. The 7 males and 8 females ranged from 21 to 78 years old. Imaging frequently revealed opacification of the paranasal sinuses. Operative reports showed all to have paranasal sinus involvement. Most were unilateral (13/15, 87%). The maxillary sinus was involved in 11/15 (73%) cases, sphenoid sinus in 2/15 (13%), and frontal and ethmoid sinuses in 1/15 (7%), each. Bacteroma patients frequently had a history of allergic rhinitis (8/15, 53%), more than mycetomas (1/15, 7%) and AFS (5/15, 33%) (P=0.0142). Facial pain was a common presenting symptom (13/15, 87%) in bacteromas compared with mycetomas (5/15, 33%) or AFS (1/15, 7%). Morphologically, cases consisted of large aggregates of paucicellular to acellular debris with a characteristic densely eosinophilic granular appearance, commonly associated with bacteria. Four of the 10 cultured patients grew Pseudomonas aeruginosa. Course posttreatment ranged from symptom resolution 1 week postoperatively to recurrent infections and symptoms 23 months from the initial operation. In summary, “bacteroma” is a heretofore undescribed pathologic entity of the sinuses that appears to be related to chronic bacterial infection and is distinct from mycetoma, AFS, and rhinolithiasis.