Clinico-pathological and molecular characteristics of pediatric-juvenile pituitary neuroendocrine tumors (PitNETs): A mono-institutional series

Our purpose was to provide a clinical-pathological overview, evaluate the prognostic value of Ki-67 and p53 in pediatric-juvenile pituitary neuroendocrine tumors (PitNETs) and explore the incidence of somatic variants in SF3B1 in pediatric-juvenile lactotroph PitNET. We present a clinical, morphological, immunohistochemical, and molecular study of 30 patients aged 8 - 20 years (16 females, 53%; 14 males, 47%). Clinical data were available for 21 patients (70%). Nine patients (43%) had mass effect symptoms. Imaging was available for 25 cases (83%). 21 patients (84%) had macro-PitNET or giant PitNET. Most tumors were lactotroph PitNETs (22 cases, 73%). Nine patients out of 22 lactotroph PitNET (41%) were male. Ki-67 and p53 immunostaining were performed in 27 cases. 15 tumors (56%) were p53 positive and exhibited a high Ki-67 index. Of these, 12 tumors (80%) were macro-PitNETs or giant PitNETs. Eight tumors (30%) were p53 negative and had low Ki-67 index, with 5 of these classified as macro-PitNETs (100% of the cases for which this data was available). Genetic analysis of the recurrent <i>SF3B1</i> c.1874G>A p.Arg625His was negative in all 15 tested tumors. In conclusion, pediatric-juvenile PitNETs are often large lesions causing mass effects in almost half of the cases. In our cohort, lactotroph PitNETs were the most frequent PitNETs and present without sex predilection. <i>SF3B1</i> mutations, documented in a proportion of adult lactotroph PitNETs, were not observed in our cohort, potentially hinting at a different molecular background. Our results did not reveal any association between Ki-67 and p53 status and tumor size or invasiveness in pediatric-juvenile PitNETs.