Comprehensive study of ancient schwannoma: Exploring histomorphological diversity and diagnostic challenges

Background: Ancient schwannoma is a rare subtype of schwannoma characterized by an extended duration of development and distinctive degenerative changes. These changes encompass relative loss of Antoni type A areas, perivascular hyalinization, hemorrhage, cystic necrosis, calcification, and the presence of atypical nuclei that can mimic sarcomatous pleomorphism. These histologic features often lead to diagnostic challenges, with ancient schwannomas frequently being misdiagnosed as malignant tumors. Objectives: This study aims to provide a comprehensive evaluation of the histomorphological spectrum observed in ancient schwannoma. Methods: A retrospective analysis was conducted on 248 schwannoma cases received at our tertiary health centre, spanning the years 2017 to 2023. Among these cases, 25 were identified as ancient schwannoma. Extensive examination of degenerative changes was performed using hematoxylin and eosin-stained paraffin-embedded tissue sections under light microscopy. Results: Patient ages ranged from 22 to 82 years, with a nearly equal distribution between genders (12 females and 13 males). Tumors were located in various anatomical sites including the forearm, brain, abdomen, retroperitoneum, intradural space, lumbar region, and pelvis. Tumor dimensions varied from 1.5 to 11 cm. Histologically, most cases exhibited nuclear atypia, cystic changes, hemorrhage, and siderophages, along with perivascular hyalinization, myxoid change, calcification, and xanthomatous change. Immunohistochemistry confirmed the neural origin of these tumors. Conclusion: Recognition of the diverse spectrum of secondary changes, coupled with the presence of focal areas showing paucicellular and cellular spindle cell arrangements, is crucial for the accurate diagnosis of ancient schwannoma. This study underscores the importance of histomorphological evaluation in distinguishing these benign tumors from malignant counterparts, thereby guiding appropriate clinical management strategies.