Great Mimics in Oncology: A Retrospective Study from a Tertiary Care Centre of Eastern India.

A number of benign diseases can masquerade as malignancy leading to unnecessary treatment. Vice versa, many benign-looking tumours when operated turns out to be malignant. While the latter necessitates extra surgery for oncological clearance, the former directly harms the patient impacting their lives seriously. Data pertaining to such "misdiagnosis" is scarce and there is an urgent need to document such cases to prevent public harm. We carried out a retrospective study to identify characteristic of such cases which were actually benign but operated upon with a diagnosis of malignancy. This is a retrospective study done at the Department of Surgical Oncology, Institute of Post Graduate Medical Education & Research (I.P.G.M.E&R). Databases from January 2022 to August 2023 were searched for patients who were initially diagnosed as cases of malignancy but later turned out to be benign. Demographic and clinicopathological data were retrieved and analysed. Out of 345 major cases, 18 cases were misdiagnosed as cancer. Three cases mimicked breast lump, two cases misdiagnosed as lymphoma, and one case each diagnosed as primary peritoneal carcinoma, carcinoma ovary, carcinoma gallbladder, and soft tissue tumour. Two cases turned out to be tuberculosis (TB), and one case was rare Castleman disease, while an unusual diagnosis of Ig4 disease was made on histopathology. Although mortality was zero, one patient had perioperative morbidity in the form of bleeding, post-op infection, and prolonged hospital stay while another patient received intraoperative brachytherapy unnecessarily. Out of 18 cases, ten cases had a preoperative cytology report suggestive of neoplasm, in three cases the biopsy/fine needle aspiration cytology (FNAC) report was inconclusive, while five patients were diagnosed based solely on clinical and radiologic findings due to an inconclusive cytology report. A benign entity can mimic cancer almost anywhere in the body. Due to close clinical, radiologic, and cytological findings, such situations are not uncommon in day to day practice. High degree of suspicion, good interdisciplinary communication, and review of slides by an experienced cytopathologist can help prevent such misdiagnosis to a good extent.