Clinicopathological Study of Extra-Axial Small Round Cell Tumors of the Cranium

The cranium is a host to a variety of neoplasms and includes small round cell tumors (SRCTs) as an important malignant subset. Although SRCTs are histomorphologically similar, they are histogenetically diverse comprising of malignancies of epithelial, hematolymphoid, neuroectodermal, and mesenchymal origin.

The study aimed to review the clinical and pathological profile of cranial SRCTs.

Study is a retrospective review (clinical, imaging, and histopathology) of cranial (extra-axial) SRCTs diagnosed on histology (period: 3.5 years).

Study included 126 cases constituting 1.5% of all intracranial neoplasms and age ranging from 11 months to 82 years (mean: 34.3 years; M:F = 1.46:1). Peripheral primitive neuroectodermal tumors (pPNET-8.2%) was the commonest neoplasm followed by plasmacytoma (14.2%), poorly differentiated carcinomas (13.5%), lymphomas (9.5%), and sarcomas (8.7%). Rare tumors included glioma (undifferentiated) deposits, germ cell tumors, melanoma, neuroendocrine neoplasms, and embryonal tumor. Children constituted one-third of the total with PNETs, embryonal tumors, and round cell sarcomas being the common neoplasms. Elderly patients constituted 14% with plasmacytomas and epithelial neoplasms being common. Three percent of the tumors remained unclassified. Clinical symptomology was location dependent, headache being the commonest followed by visual symptoms. Radiopathological discordance was high (60%).

SRCTs are unusual tumors with a wide spectrum of histogenesis, biology and clinical presentation. Their rarity in cranium, atypical localization, overlapping clinical, and imaging features pose significant difficulty for clinicians, radiologists, and pathologists. A combined algorithmic analysis of the clinical, radiological, and histolopathological findings, supplemented with immunohistochemistry can aid in specific diagnosis which is crucial for optimal management.