Background: Acute appendicitis is the one of the most common surgical emergencies in world wide. Gold standards method for diagnosis of acute appendicitis is histopathological examination of appendectomy specimen. Appendiceal lumen obstruction caused by faecolith mainly and unusual factors rarely. Spectrums of appendiceal lesions consist of inflammatory lesions to malignant lesions. Methods: The present retrospective study included 159 appendicectomy specimens received in the department of pathology, Narayana Medical College & Hospital. Nellore, Andhra Pradesh, India, during the period of January 2016 to December 2016. Appendicectomy specimens were fixed in 10% formalin and then stained with Haemotoxylin and Eosin staining technique. Results: Among the 159 appendicectomy specimens, Acute appendicitis account for 72 (45.28%) with peak occurrence in the age group 11-20 years (27.67%) and 21-30 years (25.79%) with male predominance (1.74:1). Unusual findings were noted in 21(13.21%) cases on histopathology. Most common unusual findings included chronic obliterative appendicitis (61.90%), followed by acute eosinophilic appendicitis (14.29%) and Carcinoid appendix (9.52%). Other unusual findings include Granulomatous appendicitis, Enterobius vermicularis parasitic infestation and primary adenocarcinoma of appendix. Conclusion: The gross examination of appendix during surgery cannot detect the unusual findings particularly malignancies. Histopathological examination of appendix is essential to avoid the malignancies missed and gives clinician a clear idea regarding treatment strategy.

Keywords: Appendicitis; Carcinoid; Primary Adenocarcinoma; Enterobius Vermicularis.