A “polymorphous low-grade neuroepithelial tumor of the young (PLNTY)” diagnosed in an adult. Report of a case and review of the literature
- Department of Medical, Surgical Sciences and Advanced Technologies “G.F. Ingrassia”, Anatomic Pathology, University of Catania,
- Department of Medical, Surgical Sciences and Advanced Technologies “G.F. Ingrassia”, Neurological Surgery, Policlinico “Rodolico-San Marco” University Hospital, University of Catania, 95123 Catania,
- Neuropathology Unit, Catholic University, Fondazione Policlinico Universitario “A. Gemelli” IRCSS, Rome, Italy.
Giuseppe Broggi, Department “G.F. Ingrassia”, University of Catania, Catania, Italy.
DOI:10.25259/SNI_500_2021Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Giuseppe Broggi1, Francesco Certo2, Roberto Altieri2, Rosario Caltabiano1, Marco Gessi3, Giuseppe Maria Vincenzo Barbagallo2. A “polymorphous low-grade neuroepithelial tumor of the young (PLNTY)” diagnosed in an adult. Report of a case and review of the literature. 20-Sep-2021;12:470
How to cite this URL: Giuseppe Broggi1, Francesco Certo2, Roberto Altieri2, Rosario Caltabiano1, Marco Gessi3, Giuseppe Maria Vincenzo Barbagallo2. A “polymorphous low-grade neuroepithelial tumor of the young (PLNTY)” diagnosed in an adult. Report of a case and review of the literature. 20-Sep-2021;12:470. Available from: https://surgicalneurologyint.com/surgicalint-articles/11122/
Background: Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a rare neuropathological entity, recently introduced in neuro-oncology. These tumors, histologically similar to oligodendrogliomas, cause epilepsy, occurring in children and young adults. Only few cases of PLNTY have been described in literature and all reported cases invariably focused on the onset of these tumors in children and young adults.
Case Description: We report the case of a 50-year-old woman suffering from epilepsy since the 1st year of her life. Computed tomography scan and magnetic resonance imaging of the brain documented the presence of a calcified mass involving left temporal lobe. The tumor was surgically excised and the histological examination showed a hypocellular and massively calcified neoplasm with morphological and immunohistochemical features consistent with the diagnosis of “PLNTY.”
Conclusion: A review of the literature revealed that there are 31 cases of PLNTY reported in literature, most of which are children or young adults. The present case represents the second PLNTY diagnosed in a middle-aged adult to the best of our knowledge, suggesting that PLNTY should always be included in the differential diagnosis of low-grade brain tumors, also in adult patients.
Keywords: Adult, Case report, Epilepsy, Neuroepithelial tumor, Polymorphous low-grade neuroepithelial tumor of the young
Low-grade neuroepithelial tumors represent a wide spectrum of brain lesions characterized by heterogeneous histological and molecular features, indolent biological behavior (WHO Grade I and II) and frequent association with early onset of epilepsy in children and young adults.[
We herein report a rare case of PLNTY presenting as an extensively calcified mass located to the left temporal lobe, in a 50-year-old woman with a long time history of drug-resistant epilepsy. A critical review of the scientific literature on PLNTY, highlighting that this tumor may be potentially diagnosed at any age and should not be considered only as a pediatric tumor, is also included.
History and clinical findings
A 50-year-old lady, left handed, was referred to the department of neurological surgery, because of a drug-resistant epilepsy. She had a medical history, featured by the onset of seizures since early childhood. The patient was treated over several years with a combination of different anti-epileptic drugs, but she never obtained a complete control of seizures. During the past 2 years before admission, the patient experienced the worsening of crises. These were featured by mental confusion, reduced consciousness, dyskinesia in the upper right limb, and gaze deviation towards the right side. The crises occurred with a frequency of 3–4 episodes per day and occasionally had secondary generalization. She had also hypothyroidism. When the patient was hospitalized, neurological examination revealed moderate mental impairment with slowed speech and gait. Neuroradiological assessment was performed. Brain computed tomography (CT) revealed the presence of a densely calcified lesion involving left temporal lobe and insula [
Preoperative neuroradiological assessment. Computed tomography scan (a) demonstrating the presence of a densely calcified left temporal and insular lesion. FLAIR sequences of magnetic resonance (MR) scan confirmed the presence of the calcified tumor (b). Postoperative MR confirmed the complete resection of the lesion (c).
The patient was positioned supine with the left shoulder elevated and head 60° rotated to the right side and fixed by radiolucent three-point Mayfield clamp. Preoperative CT scan with and without iodinate contrast was performed after positioning. Images of postpositioning CT scan were merged with preoperative MRI and used for neuronavigation. Motor evoked potentials, somatosensory evoked potentials and direct monopolar and bipolar cortical and subcortical stimulation were used for neuromonitoring. The intraoperative imaging protocol used in the present case has been previously detailed.[
Postoperative course and outcome
Postoperative MRI confirmed the radical resection of the lesion [
Grossly, the tumor sample consisted of multiple fragments, markedly hard in consistency, measuring 2 cm in aggregate diameter. Histologic examination showed an extensively calcified and hypocellular lesion [
Histological examination. (a) Low magnification showing the densely calcified nature of the tumor mass (hematoxylin and eosin; original magnification 25×); (b) tumor was mainly composed of small and roundish cells with oligodendroglioma-like morphology intermingled with calcifications ranging from small calcospherules to larger and confluent psammomatous bodies (hematoxylin and eosin; original magnification 150×); (c) a less represented neoplastic component with astrocytic-like morphology was also found (hematoxylin and eosin; original magnification 50×); (d) neoplastic cells were diffusely and strongly stained with CD34 (immunoperoxidase; original magnification 50×).
Apart from the most common glial tumors,[
Based on both the facts that PLNTY has a distinct DNA methylation profile and almost invariably presents genetic features involving the MAP kinase pathway components, such as BRAF-V600E mutations or FGFR3- transforming acidic coiled-coil-containing protein 3 (TACC3), FGFR2-KIAA1598, and FGFR2-CTNNA3 fusions, it has now been widely accepted that PLNTY is a distinct tumor entity, belonging to the wide spectrum of low-grade neuroepithelial neoplasms.[
The unusual age of onset of the present case led us to critically perform a literature review and we found that, since its first description,[
The two most peculiar features of the present case were the age at the diagnosis and the onset as a lowly cellular and diffusely calcified nodule. Even in this regard, we retrospectively reviewed the scientific literature to investigate the presence of papers focusing on the calcified aspect of PLNTY nodules; Johnson et al. in 2019[
On the histopathological point of view, as PLNTY is a round cell with clear perinuclear halo tumor; the differential diagnosis usually includes CNS round/clear cell neoplasms (oligodendroglioma, clear cell ependymoma, and PA with oligodendroglioma-like features) that, however, can be excluded due to the combination of morphological, immunohistochemical (CD34 strong and diffuse expression), and molecular features of PLNTY.[
Moreover, the diagnostic pre- and intra-operative diagnostic assessment used in this case and commonly applied at our institution for all intrinsic brain lesion allowed a thorough study of imaging features of PLNTY. These tumors have common radiological features with calcified cavernous malformations and oligodendrogliomas. i-US revealed a hyperechoic lesion with characteristic posterior shadowing due to the presence of calcium. We also documented that these lesions do not show any 5-ALA induced fluorescence, under ultraviolet light. The present case represents the second confirmed report of PLNTY arising in a middle-aged patient and it led us to reflect on the real need to no longer consider PLNTY as a tumor of the pediatric/young age; although it is likely that, being a slow-growing neoplasm, PLNTY arises at an early age and then is diagnosed late, it is also true that, as PLNTY is associated in almost all cases with the onset of seizures, the hypothesis that a patient can neglect the symptoms and not undergo further diagnostic tests is quite remote.
The present case emphasizes the concept that, in the presence of an appropriate clinicoradiological context, neuroradiologists, neurosurgeons, and neuropathologists must include PLNTY in the differential diagnosis even in presence of an adult patient.
Patient’s consent not required as patients identity is not disclosed or compromised.
There are no conflicts of interest.
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