Are we over treating Pineal Parenchymal tumour with intermediate differentiation? Assessing the role of localised radiation therapy and literature review

Abstract

Pineal Parenchymal tumour with intermediate differentiation (PPTID) is a rare disorder, first classified by World Health Organisation in 2000. There are very few published data available and optimal management is yet to be determined. Management has varied from surgery alone to craniospinal radiotherapy with or without chemotherapy. We present our experience of PPTID treated with radiotherapy alone. We conducted a retrospective review of patients who were diagnosed with PPTID and treated with radiation therapy at our institute from 2010 onwards. Between January 2010 to January 2013, 5 patients of PPTID were treated at our institute. Median age is 44 (range 24-62). All patients had preoperative MRI scan of brain and spine. Imaging did not identify any spinal dissemination. None of the patients underwent a gross total resection, due to the tumour location and technical difficulties. All patients were treated with external beam radiation therapy to primary lesion only with a dose of 54 Gy in 30 fractions after surgery. 4 patients had good partial response and the remaining 1 has stable disease. After 21.4 months of median follow up no disease recurrence was reported. So far there is no evidence of cerebral white matter abnormalities on MRI scan or neurocognitive disorders. Our experience indicated that localised radiation therapy could be an effective treatment strategy for PPTID, considering the long natural course of the disease and the late adverse effects of intensive treatment.

Keywords: Chemotherapy; Pineal Parenchymal tumour; Pineal Parenchymal tumour with intermediate differentiation (PPTID); Radiotherapy.

Fig. 1

a Malignant pineocytes with stippled nuclear chromatin and moderately eosinophilic cytoplasm arranged around a Homer-Wright rosette.                         b MIB-1 demonstrating a low proliferative index. c Frozen section image: tumour appear more closely packed with denser chromatin. Apoptotic bodies are visible (arrow). d Synaptophysin immunochemistry showing granular cytoplasomic positivity. e Strong neurofilament staining on all cells

Fig. 2

a Malignant pineocytes exhibit increased nuclear pleomorphism. A mitotic figure is present (arrow). b MIB-1 demonstrating higher proliferative index. c Weak, patchy neurofilament staining positivity most cells are negative

Fig. 3

CT scan a shows homogenous mass in pineal region with peripheral calcification and obstructive hydrocephalus. b T2-weighted MRI shows multiple small cysts within the mass and probable invasion of left thalamus, c confirmed on T1-weighted scan after intravenous Gadolinium. d Diffusion-weighted scan (b = 1000) shows small area of diffusion restriction anteriorly within the tumour (confirmed on Apparent Diffusion Coefficient map), close to the left thalamus

Fig. 4

T1-weighted MRI scan after intravenous Gadolinium a shows patchy enhancement of mass in pineal region and obstructive hydrocephalus. No evidence of local invasion. b Single-voxel MR spectroscopy (TE = 144) shows moderate elevation of Choline, reduction in NAA and inverted lactate doublet

Fig. 5

Patient with good PR (partial response). Axial and coronal T1-weighted MRI scans with intravenous Gadolinium, before (a and b) and after (c and d) treatment