Histopathological Spectrum of Rare and Diverse Lesions of Vestigial Appendix: A Cross-sectional Study from a Tertiary Care Hospital in Marathwada Region of Maharashtra, India

Introduction: The appendix, though often associated with acute appendicitis, can present with a variety of pathologies, some of which have significant clinical implications. These include rare inflammatory, infectious, and neoplastic conditions that highlight the diagnostic and therapeutic importance of histopathological evaluation. Aim: To study the spectrum of diverse appendiceal lesions, focusing on their histopathological characteristics and clinical relevance. Materials and Methods: The present retrospective crosssectional study analysed 32 appendectomy specimens with rare lesions (January 2022- May 2024) in the Department of Surgical Pathology of a Tertiary Care Hospital in the Marathwada Region of Maharashtra, India. Histopathological evaluation included Haematoxylin and Eosin (H&E) staining, special stains {e.g., Ziehl-Neelsen, Periodic Acid-Schiff (PAS) stain}, Tuberculosispolymerase Chain Reaction (TB-PCR), and Immunohistochemistry (IHC) for neoplastic cases. Demographics, clinical-radiological data, and histopathological parameters (H&E, special stains, IHC) and TB-PCR wherever needed were analysed. Results were presented as frequencies/percentages using Statistical Package for Social Sciences (SPSS) v24.0 software. Results: Histopathological analysis identified 13 distinct pathologies among 32 cases: tuberculous appendicitis 5 5 (15.6%), Low-grade Appendiceal Mucinous Neoplasms (LAMN) 8 (25%), appendiceal neuromas 8 (25%), Inflammatory Myofibroblastic Tumour (IMT) 1 (3.1%), and leukaemic infiltration 1 (3.1%). Other significant findings included deposits of mucinous adenocarcinoma 1 (3.1%), Neuroendocrine Tumour (NETs) 1 (3.1%), and appendiceal diverticulum 1 (3.1%). Infectious aetiologies included tapeworm 1 (3.1%) and parasitic infestations 2 (6.25%) and one case of amoebic appendicitis 1 (3.1%). Additionally, mesothelial inclusion cysts 1 (3.1%) and lymphangiectasia 1 (3.1%) were identified. The clinical relevance of each lesion was evaluated by reviewing patient records and operative notes wherever available, and interpreting the potential diagnostic and therapeutic implications of the histological findings. Conclusion: Histopathological evaluation of appendectomy specimens is crucial for identifying diverse appendiceal lesions, many of which may mimic acute appendicitis clinically. Gross (especially the base of the appendix) and microscopy of every appendix needs to be studied meticulously, irrespective of the clinical diagnosis. Early identification and accurate diagnosis are essential for guiding patient management and improving outcomes. While tuberculous appendicitis and parasitic infections are more common in endemic regions, neoplastic lesions such as LAMN and NETs carry significant implications for prognosis and treatment. Rare entities like appendiceal neuromas and IMT further emphasise the diagnostic value of histopathological examination.