MICROSCOPY 1. to 3. Biopsies are from one intraoperative lesion and are described together. There is a pleomorphic neoplasm infiltrating the leptomeningeal space and extending into the cortex along Virchow-Robin space (also seen in specimens 2 and focally in specimen 3). The cells show nuclear pleomorphism with eosinophilic nucleoli and cytoplasmic melanin, and form sheet-like nodules with brain invasion. No necrosis is present and mitotic figures are not seen (0/10 HPF). The neoplastic cells express SOX10 and HMB45 (majority of cells). Ki67 proliferation index is estimated at 5%. The neoplasm shows pleomorphic melanocytes with leptomeningeal spread and brain invasion. The features are of leptomeningeal melanomatosis. Radiological features in favour of metastatic disease is noted, and the differential diagnosis with a primary process is not completely excluded on this histology. Clinical correlation is required.
SUPPLEMENTARY REPORT: c-Kit staining requested by clinician. c-Kit staining is positive.
SUMMARY 1.-3. Cortex, left frontal lobe; Parenchyma, left frontal lobe; Deep lesional tissue - Leptomeningeal melanomatosis, please see description
Report prepared by Dr. Ming Yu, Consultant Pathologist