Adenocarcinoma of the frontal sinus is extremely rare. We present a primary frontal sinus adenocarcinoma masquerading as an inverted papilloma (IP). Here, we reviewed various clinical presentations, investigations, and management of frontal sinus adenocarcinoma. A 48-year-old male presented with nasal bridge swelling one month following endoscopic sinus surgery for frontal sinus inverted papilloma. Progressively enlarging swelling with persistent pressure symptoms drew doubts regarding previously proven diagnosis. Imaging studies put us at the management crossroads of malignancy versus infection (osteomyelitis). The complexity of this case prompted a multidisciplinary team approach, eventually leading to a revision surgery for re-evaluation. Re-excision of the frontal sinus tumor was later proven to be adenocarcinoma of the frontal sinus. This case underscores the importance of thorough follow-up and investigation in patients presenting with recurrent or persistent symptoms following sinus surgery. This case highlighted the need for a high index of suspicion and comprehensive diagnostic workup.