Adequate sampling of gross pathology specimens and attention to microscopic details is crucial in establishing the correct diagnosis in a patient, regardless of a benign pre-surgical diagnosis. Adenoma malignum is a rare HPV-negative variant of well-differentiated adenocarcinoma of the endocervix. It is difficult to diagnose in surgical pathology specimens due to its deceptively-benign appearance. This was a case of a 43-year-old woman with a history of menorrhagia and metrorrhagia and radiology interpretation of degenerating uterine fibroids. Pre-operative Pap testing and hysteroscopic dilatation and curettage were non-contributory. Following surgery, microscopic examination of the cervix revealed well-spaced, deeply-invasive, variably-sized glands with irregular outlines/haphazard arrangements, lined by cells showing mild to moderate cytologic atypia. These cells were positive for p53 and CK7 on Immunohistochemistry and Ki-67 showed a high proliferative index. Monoclonal CEA, calretinin, CD10, and P16 were all negative. A diagnosis of adenoma malignum stage pT1b2 was made. The patient was subsequently placed on platinum-based chemotherapy and is doing well 2 years after her diagnosis. Cases such as this, underscore the importance of adequately sampling surgical resection specimens, with careful attention to microscopic details as incidental pathologies may be unearthed which could have significant implications on a patient's clinical outcome.