Unexpected Presentations of Histiocytic Disorders as Mass Lesions in the Central Nervous System and Spine

Abstract Introduction/Objective A number of neoplastic and non-neoplastic hematolymphoid lesions can involve the CNS and spine. The majority are lymphomas, but some are rare lesions that mimic primary neoplasms clinically, radiologically, and even pathologically. Here, we present our experience of such cases. Methods/Case Report Pathology archives were searched, and five cases representing different challenges were identified to review clinical, radiological, and pathologic features. Case 1. 31-year-old female presented with vision changes and hearing loss and numerous supratentorial extra-axial masses, suspicious for meningiomatosis. Extensive lymphoplasmacytic infiltrate was seen at Intraoperative consult (IOC). Final diagnosis was Rosai-Dorfman disease with features of IgG4 related disease. Case 2. 31-year-old female with Chronic myeloid leukemia (CML), which progressed to AML presented with a right frontal brain mass. IOC displayed atypical hematolymphoid infiltrate. Final diagnosis was myeloid sarcoma. Case 3. 29-year-old male presented with a T10 vertebral lesion. IOC showed hypercellular tissue with atypia and was deferred. Subsequently, histiocytic sarcoma was diagnosed. Case 4. 22-year- old male presented with a T3-T4 intradural, extramedullary mass radiologically thought to be a meningioma. No IOC was requested. Final diagnosis was juvenile xanthogranuloma. Case 5. 36-year-old male presented with a C7-T1 dura-based mass. IOC revealed granulomatous inflammation, eventually resulting in a diagnosis of non-necrotizing granulomatous inflammation, suggesting sarcoidosis. Results (if a Case Study enter NA) NA Conclusion These cases highlight the importance of incorporating all clinical and radiological findings into pathologic evaluation, while being alert for mimickers and pitfalls. Both practicing general surgical pathologists and neuropathologists should remain alert to such unexpected and unusual cases especially at the time of IOC and initiate appropriate work-up with expedited diagnostic protocols such as intraoperative cultures, flow cytometry, and cytogenetics, as the differential diagnosis is broad with inflammatory, infectious, and neoplastic possibilities, presenting a variety of challenges.