Polymorphous low-grade neuroepithelial tumor of the young (PLNTY)
General description
Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a recently described epileptogenic neoplasm that occurs primarily in children and young adults. The mean age at diagnosis is 22.16 years, with a range of 4-57 years. However, despite its name suggesting it affects only the young, PLNTY has been documented in older adults.
The most common clinical manifestation of PLNTY is drug-resistant epilepsy, occurring in approximately 73.7% of patients chronic and have often been present for years before diagnosis. Other less common presentations include headache, visual disturbances, and incidental findings following trauma.
Long-term epilepsy-associated tumors (LEATs)
Long-term epilepsy-associated tumors are cortically based, WHO grade 1 neoplasms that
- present with a history of ≥ 2 years of pharmacoresistant focal epilepsy,
- occur predominantly in the first two decades,
- grow indolently, and
- often display mixed glial–neuronal differentiation and perilesional cortical dysplasia.
Classic representatives are ganglioglioma and DNET; newer entities such as angiocentric glioma, isomorphic diffuse glioma and PLNTY were later integrated as molecular data accumulated.
References
- Abdelzaher E. Polymorphous low grade neuroepithelial tumor of the young (PLNTY). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumorplnty.html.
- Cerron-Vela, Carmen, et al. "Expanding the Imaging Spectrum of Polymorphous Low-Grade Neuroepithelial Tumor of the Young in Children." American Journal of Neuroradiology 45.4 (2024): 483-487.
Cortical-subcortical mass
PLNTY is an intraparenchymal brain tumor that arises within the brain substance rather than from extraparenchymal structures. The tumors characteristically originate from the cortex and subcortical white matter, demonstrating a cortical-subcortical distribution pattern in approximately 80% of cases.
The temporal lobe is the most frequent location, accounting for approximately 65-80% of cases, with a notable right-sided predominance.
PLNTY demonstrates variable margin characteristics depending on the age group. In pediatric cases, ill-defined margins are seen in 90% of cases, while well-circumscribed margins with clear demarcation from surrounding brain tissue may be observed in adult cases.
PLNTY typically demonstrates iso- to hypointense signal intensity on T1-weighted images relative to normal brain tissue. The tumors characteristically show heterogeneous hyperintense signal on T2-weighted and FLAIR sequences. PLNTY typically does not demonstrate restricted diffusion on diffusion-weighted imaging (DWI), with no abnormal signal on apparent diffusion coefficient (ADC) maps. Contrast enhancement in PLNTY is typically minimal or absent, occurring in only a minority of cases (approximately 25-40%).
Calcification is one of the most characteristic CT features of PLNTY, present in 70-91% of cases. The calcifications may evolve over time: in pediatric cases, punctate calcifications (also called "salt and pepper pattern") are more common, while coarse, central calcifications are typical in adult cases.
Cystic components are present in the majority of PLNTY cases (approximately 80-89%), typically located at the tumor periphery. The cystic areas appear hypointense on T1-weighted images and hyperintense on T2-weighted and FLAIR sequences.
PLNTY typically produces minimal mass effect and perilesional edema due to its slow growth pattern. Hemorrhage and necrosis are also characteristically absent in PLNTY.
Transmantle sign
In some pediatric cases, a transmantle-like sign can be observed, representing extension of abnormal tissue from the ventricular surface to the cortex, though this is not a consistent feature.