Malignancy mimics- diagnostic perplexities for oral and maxillofacial pathologists

OBJECTIVE: In pathology practice, one frequently encounters benign lesions which superficially resemble malignancy clinically and histopathologically. The diagnostic pitfalls can be avoided if the approach exemplified in the present study is followed. We expect that familiarity of these cases will be helpful for pathologists at the beginning of their career. METHODS: Clinical case records of all the pathological specimens reported in our laboratory from January 2018 to September 2019 were queried. Cases displaying pseudotumor features were reviewed along with the special stains were performed and immunohistochemistry (IHC) studies. A working classification of pseudotumors presenting in the oral cavity was proposed. RESULTS: Immunoglobulin G4-related disease, nodular fasciitis, fibrolipoma, odontogenic keratocyst with giant cell granuloma, juvenile ossifying fibroma with central giant cell granuloma and tumor-induced osteomalacia were the most common diagnoses where the tissue specimens resembled malignancies on routine clinicoradiological evaluation and light microscopy of tissue specimens. Their differential diagnosis and the pathological diagnostic dilemmas are explained. We have also highlighted the importance of correlating clinical, radiological and microscopic details with the findings deduced from advanced pathological aids to establish the final diagnosis. CONCLUSIONS: Pathologists should be aware of the conditions where the diagnosis of malignancy needs stricter evaluation to rule out malignant mimics. In such scenarios, correlation of light microscopy findings with clinical and radiological details cannot be overemphasized. Advanced pathological aids such as IHC, where necessary are often indispensable for reaching the accurate diagnosis in these cases.