A rare case of mesenteric intranodal schwannoma

Abstract

Intranodal schwannomas are an extremely rare pathology with broad differential diagnoses of benign and malignant spindle cell lesions. This case reports a 71-year-old female who presented with abdominal discomfort and was found to have a 6 cm small bowel mesentery mass. The patient proceeded to have the mass laparoscopically resected. Histological examination revealed an encapsulated lesion composed of spindle cells with remnant lymph node architecture at the peripheries. These findings proposed a broad list of differential diagnoses, including metastatic melanoma, GIST, spindle cell carcinomas, spindle cell sarcomas, myofibroblastoma and leiomyoma. Immunohistochemistry revealed the lesion was positive for neural markers S100 and Sox10, and negative for cytokeratins, melanoma markers and GIST markers, favouring the diagnosis of an intranodal schwannoma. A literature review found only six other cases of intranodal schwannoma. These cases described similar morphology but exhibited great variability in the reported immunohistochemical analysis. This rare case demonstrates the importance of considering broad differential diagnoses in cases of intranodal spindle cell lesions and the use of immunohistochemical methods to exclude more sinister pathologies.