Intramedullary Spinal Ependymoma with Signet Ring Cell/Adipocytic Morphology- A Rare Case Report

Ependymoma is neuroepithelial tumour with ependymal differentiation that most commonly has ventricular involvement and arises in the cerebrum and spinal cord. It has bimodal age distribution. Incidence rate highest in infant less than one year and second peak is in the 4th decade. Ependymoma with signet ring type of morphology is rare variant. A 57-year-old male patient came with complaints of tingling sensation over bilateral upper limbs. Magnetic Resonance Imaging (MRI) showed cervical intramedullary well defined short segment solid-cystic lesion. Microscopy showed perivascular pseudorosettes and some ependymal rosette focally, in a fibrillary background. Cell forming pseudorosettes have clear vacuolated cytoplasm with eccentrically placed nucleus giving signet ring/mature adipocytic morphology. Thick walled hyalinised blood vessels, occasional mitosis were seen. On histomorphology differential diagnosis were ependymoma with signet ring/adipocytic morphology grade II and metastatic adenocarcinoma with signet ring cell morphology. The cells were positive for Glial Fibrillary Acidic Protein (GFAP), perinuclear dot like positivity for Epithelial Membrane Antigen (EMA). Cell show focal nuclear positivity for Cyclin-D1. MIB-1 (cell proliferation marker) index was 1-2% in highest proliferating. Final impression was ependymoma WHO grade II with signet ring/Adipocytic morphology. Clinically the prognosis of this histological type remains same as conventional ependymoma. These patterns are not decisive for clinical prognosis and treatment. It is necessary to differentiate it from metastasis of signet ring cell adenocarcinoma as the management of such cases is completely different from ependymoma.