Anaplastic sarcoma of the kidney (DICER1-sarcoma of the kidney): A report from the International Pleuropulmonary Blastoma/DICER1 Registry.

BACKGROUND: Anaplastic sarcoma of the kidney (ASK) is a DICER1-related neoplasm first identified as a distinctive tumor type through the evaluation of unusual cases of putative anaplastic Wilms tumors. Subsequent case reports identified the presence of biallelic DICER1 variants as well as progression from cystic nephroma, a benign DICER1-related neoplasm. Despite increasing recognition of ASK as a distinct entity, the optimal treatment remains unclear. METHODS: Individuals with known or suspected DICER1-related tumors including ASK were enrolled in the International Pleuropulmonary Blastoma/DICER1 Registry. Additionally, a comprehensive review of reported cases of ASK was undertaken, and data were aggregated for analysis with the aim to identify prognostic factors and clinical characteristics to guide decisions regarding genetic testing, treatment, and surveillance. RESULTS: Ten cases of ASK were identified in the Registry along with 37 previously published cases. Staging data, per Children's Oncology Group guidelines, was available for 40 patients: 13 were stage I, 12 were stage II, 10 were stage III, and five were stage IV. Outcome data were available for 37 patients. Most (38 of 46) patients received upfront chemotherapy and 14 patients received upfront radiation. Two-year event-free survival (EFS) for stage I-II ASK was 81.8% (95% confidence interval [CI]: 67.2%-99.6%), compared with 46.6% EFS (95% CI: 24.7%-87.8%) for stage III-IV (p = .07). Two-year overall survival (OS) for stage I-II ASK was 88.9% (95% CI: 75.5%-100.0%), compared with 70.0% (95% CI: 46.7%-100.0%) for stage III-IV (p = .20). Chemotherapy was associated with improved EFS and OS with hazard ratios of 0.09 (95% CI: 0.02-0.31) and 0.08 (95% CI: 0.02-0.42), respectively. CONCLUSION: ASK is a rare DICER1-related renal neoplasm. In the current report, we identify clinical and treatment-related factors associated with outcome including the importance of chemotherapy in treating ASK. Ongoing data collection and genomic analysis are indicated to optimize outcomes for children and adults with these rare tumors.

Outcomes in ovarian Sertoli-Leydig cell tumor: A report from the International Pleuropulmonary Blastoma/DICER1 and Ovarian and Testicular Stromal Tumor Registries.

OBJECTIVE: Sertoli-Leydig cell tumors (SLCTs) are rare sex cord-stromal tumors, representing <0.5% of all ovarian tumors. We sought to describe prognostic factors, treatment and outcomes for individuals with ovarian SLCT. METHODS: Individuals with SLCT were enrolled in the International Pleuropulmonary Blastoma/DICER1 Registry and/or the International Ovarian and Testicular Stromal Tumor Registry. Medical records were systematically abstracted, and pathology was centrally reviewed when available. RESULTS: In total, 191 participants with ovarian SLCT enrolled, with most (92%, 175/191) presenting with FIGO stage I disease. Germline DICER1 results were available for 156 patients; of these 58% had a pathogenic or likely pathogenic germline variant. Somatic (tumor) DICER1 testing showed RNase IIIb hotspot variants in 97% (88/91) of intermediately and poorly differentiated tumors. Adjuvant chemotherapy was administered in 40% (77/191) of cases, and among these, nearly all patients received platinum-based regimens (95%, 73/77), and 30% (23/77) received regimens that included an alkylating agent. Three-year recurrence-free survival for patients with stage IA tumors was 93.6% (95% CI: 88.2-99.3%) compared to 67.1% (95% CI: 55.2-81.6%) for all stage IC and 60.6% (95% CI: 40.3-91.0%) for stage II-IV (p < .001) tumors. Among patients with FIGO stage I tumors, those with mesenchymal heterologous elements treated with surgery alone were at higher risk for recurrence (HR: 74.18, 95% CI: 17.99-305.85). CONCLUSION: Most individuals with SLCT fare well, though specific risk factors such as mesenchymal heterologous elements are associated with poor prognosis. We also highlight the role of DICER1 surveillance in early detection of SLCT, facilitating stage IA resection.

Prevalence of lung cysts in adolescents and adults with a germline DICER1 pathogenic/likely pathogenic variant: a report from the National Institutes of Health and International Pleuropulmonary Blastoma/DICER1 Registry.

BACKGROUND: Pleuropulmonary blastoma (PPB), the hallmark tumour associated with DICER1-related tumour predisposition, is characterised by an age-related progression from a cystic lesion (type I) to a high-grade sarcoma with mixed cystic and solid features (type II) or purely solid lesion (type III). Not all cystic PPBs progress; type Ir (regressed), hypothesised to represent regressed or non-progressed type I PPB, is an air-filled, cystic lesion lacking a primitive sarcomatous component. This study aims to evaluate the prevalence of non-progressed lung cysts detected by CT scan in adolescents and adults with germline DICER1 pathogenic/likely pathogenic (P/LP) variants. METHODS: Individuals were enrolled in the National Cancer Institute Natural History of DICER1 Syndrome study, the International PPB/DICER1 Registry and/or the International Ovarian and Testicular Stromal Tumor Registry. Individuals with a germline DICER1 P/LP variant with first chest CT at 12 years of age or older were selected for this analysis. RESULTS: In the combined databases, 110 individuals with a germline DICER1 P/LP variant who underwent first chest CT at or after the age of 12 were identified. Cystic lung lesions were identified in 38% (42/110) with a total of 72 cystic lesions detected. No demographic differences were noted between those with lung cysts and those without lung cysts. Five cysts were resected with four centrally reviewed as type Ir PPB. CONCLUSION: Lung cysts are common in adolescents and adults with germline DICER1 variation. Further study is needed to understand the mechanism of non-progression or regression of lung cysts in childhood to guide judicious intervention.

Intronic Germline DICER1 Variants in Patients With Sertoli-Leydig Cell Tumor.

Germline pathogenic loss-of-function (pLOF) variants in DICER1 are associated with a predisposition for a variety of solid neoplasms, including pleuropulmonary blastoma and Sertoli-Leydig cell tumor (SLCT). The most common DICER1 pLOF variants include small insertions or deletions leading to frameshifts, and base substitutions leading to nonsense codons or altered splice sites. Larger deletions and pathogenic missense variants occur less frequently. Identifying these variants can trigger surveillance algorithms with potential for early detection of DICER1-related cancers and cascade testing of family members. However, some patients with DICER1-associated tumors have no pLOF variants detected by germline or tumor testing. Here, we present two patients with SLCT whose tumor sequencing showed only a somatic missense DICER1 RNase IIIb variant. Conventional exon-directed germline sequencing revealed no pLOF variants. Using a custom capture panel, we discovered novel intronic variants, ENST00000343455.7: c.1752+213A>G and c.1509+16A>G, that appear to interfere with normal splicing. We suggest that when no DICER1 pLOF variants or large deletions are discovered in exonic regions despite strong clinical suspicion, intron sequencing and splicing analysis should be performed.

Congenital Pulmonary Airway Malformations With a Reconsideration and Current Perspective on the Stocker Classification.

Congenital cystic pulmonary lesions (CCPLs) are represented by the following entities: congenital pulmonary airway malformation (CPAM), formerly congenital cystic adenomatoid malformation, extra- and intralobar sequestration (EIS), congenital lobar emphysema (overexpansion), and bronchogenic cyst. The developmental model of CPAM histogenesis by Stocker proposed perturbations designated as CPAM type 0 to type 4 without known or specific pathogenetic mechanisms along the airway from the bronchus to the alveolus. This review highlights mutational events either at the somatic level in KRAS (CPAM types 1 and possibly 3) or germline variants in congenital acinar dysplasia, formerly CPAM type 0, and pleuropulmonary blastoma (PPB), type I, formerly CPAM type 4. The potential for overt malignant progression exists in the case of PPB type I and CPAM type 1 in some cases to well-differentiated mucinous adenocarcinoma. On the other hand, CPAM type 2 is an acquired lesion resulting from interruption in lung development secondary to bronchial atresia. The latter is also regarded as the etiology of EIS whose pathologic features are similar, if not identical, to CPAM type 2. These observations have provided important insights into the pathogenetic mechanisms in the development of the CPAMs since the Stocker classification.

A Single Dose of Ibuprofen Impacts IL-10 Response to 164-km Road Cycling in the Heat.

Purpose: The purpose was to determine the effect of a single-dose prophylactic ibuprofen use before a 164-km road cycling event in high ambient temperature on the circulating cytokine and leukocyte responses. Methods: Twenty-three men (53 ± 8 y, 172.0 ± 22.0 cm, 85.1 ± 12.8 kg, 19.6 ± 4.4% body fat) completed a 164-km self-paced recreational road cycling event in a hot, humid, sunny environment (WBGT = 29.0 ± 2.9°C) after consuming 600 mg of ibuprofen (n = 13) or a placebo (n = 10). Blood samples were obtained one to two hours before (PRE) and immediately after (POST) the event, and analyzed for concentrations of circulating cytokines interleukins (IL)-1ß, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, GM-CSF, IFN-γ, and TNF-α and leukocytes (total leukocytes, granulocytes, monocytes, and lymphocytes). Results: Event completion time was 400.2 ± 74.8 min. Concentrations of all cytokines (except IL-1ß, IL-2, IL-5, IL-12, GM-CSF, and IFN-γ) and of all leukocyte subsets increased from PRE to POST. Ibuprofen ingestion attenuated the increase in IL-10 (86% increase with Ibuprofen; 270% increase with placebo). Conclusions: Consuming 600 mg of Ibuprofen prior to a 164-km road cycling event in a hot-humid environment attenuates exercise-induced increases in the concentration of the anti-inflammatory cytokine IL-10, but does not alter the effect of the exercise event on concentrations of other circulating cytokines or leukocyte subset concentrations.

Type I and Ir pleuropulmonary blastoma (PPB): A report from the International PPB/DICER1 Registry.

BACKGROUND: Pleuropulmonary blastoma (PPB) is the most common lung cancer of infancy and early childhood. Type I PPB is a purely cystic lesion that has a microscopic population of primitive small cells with or without rhabdomyoblastic features and may progress to type II or III PPB, whereas type Ir lacks primitive small cells. METHODS: Children with suspected PPB were enrolled in the International PPB/DICER1 Registry. Pathology was centrally reviewed, and follow-up was ascertained annually. RESULTS: Between 2006 and 2022, 205 children had centrally reviewed type I or Ir PPB; 39% of children with type I and 5% of children with type Ir PPB received chemotherapy. Outcomes were favorable, although 11 children (nine with type I and two with type Ir PPB) experienced progression to type II/III (n = 8) or regrowth of type I PPB at the surgical site (n = 3), none of whom received chemotherapy before progression. Age and cyst size in combination were more suitable than either factor alone in predicting whether a particular lesion was type I or Ir PPB. CONCLUSIONS: For young children with type I PPB, outcomes are favorable, but complete resection is indicated because of the risk for progression. Chemotherapy may be useful in a subset of children at increased risk for recurrence/progression. Efforts to risk stratify children with type I PPB to optimize outcomes while reducing treatment-related side effects are underway.

Outcomes for Children With Type II and Type III Pleuropulmonary Blastoma Following Chemotherapy: A Report From the International PPB/DICER1 Registry.

PURPOSE: Pleuropulmonary blastoma (PPB) is the most common primary lung neoplasm of infancy and early childhood. Type II and type III PPB have historically been associated with a poor prognosis. METHODS: Patients with known or suspected PPB were enrolled in the International PPB/DICER1 Registry. Medical records were abstracted with follow-up ascertained annually. All PPB diagnoses were confirmed by central pathology review. Beginning in 2007, the IVADo regimen (ifosfamide, vincristine, actinomycin-D, and doxorubicin) was recommended as a potential treatment regimen for children with type II and type III PPB. This regimen was compared with a historical control cohort. RESULTS: From 1987 to 2021, 314 children with centrally confirmed type II and type III PPB who received upfront chemotherapy were enrolled; 132 children (75 with type II and 57 with type III) received IVADo chemotherapy. Adjusted analyses suggest improved overall survival for children treated with IVADo in comparison with historical controls with an estimated hazard ratio of 0.65 (95% CI, 0.39 to 1.08). Compared with localized disease, distant metastasis at diagnosis was associated with worse PPB event-free survival and overall survival with hazard ratio of 4.23 (95% CI, 2.42 to 7.38) and 4.69 (95% CI, 2.50 to 8.80), respectively. CONCLUSION: The use of IVADo in children with type II and type III PPB resulted in similar-to-improved outcomes compared with historical controls. Inferior outcomes with metastatic disease suggest the need for novel therapies. This large cohort of uniformly treated children with advanced PPB serves as a benchmark for future multicenter therapeutic studies for this rare pediatric tumor.

Revisiting the Threshold for Cancer Genetics Referral in Patients With Wilms Tumor.

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in the Journal of Clinical Oncology, to patients seen in their own clinical practice.

DICER1 tumor predisposition syndrome: an evolving story initiated with the pleuropulmonary blastoma.

DICER1 syndrome (OMIM 606241, 601200) is a rare autosomal dominant familial tumor predisposition disorder with a heterozygous DICER1 germline mutation. The most common tumor seen clinically is the pleuropulmonary blastoma (PPB), a lung neoplasm of early childhood which is classified on its morphologic features into four types (IR, I, II and III) with tumor progression over time within the first 4-5 years of life from the prognostically favorable cystic type I to the unfavorable solid type III. Following the initial report of PPB, its association with other cystic neoplasms was demonstrated in family studies. The detection of the germline mutation in DICER1 provided the opportunity to identify and continue to recognize a number seemingly unrelated extrapulmonary neoplasms: Sertoli-Leydig cell tumor, gynandroblastoma, embryonal rhabdomyosarcomas of the cervix and other sites, multinodular goiter, differentiated and poorly differentiated thyroid carcinoma, cervical-thyroid teratoma, cystic nephroma-anaplastic sarcoma of kidney, nasal chondromesenchymal hamartoma, intestinal juvenile-like hamartomatous polyp, ciliary body medulloepithelioma, pituitary blastoma, pineoblastoma, primary central nervous system sarcoma, embryonal tumor with multilayered rosettes-like cerebellar tumor, PPB-like peritoneal sarcoma, DICER1-associated presacral malignant teratoid neoplasm and other non-neoplastic associations. Each of these neoplasms is characterized by a second somatic mutation in DICER1. In this review, we have summarized the salient clinicopathologic aspects of these tumors whose histopathologic features have several overlapping morphologic attributes particularly the primitive mesenchyme often with rhabdomyoblastic and chondroid differentiation and an uncommitted spindle cell pattern. Several of these tumors have an initial cystic stage from which there is progression to a high grade, complex patterned neoplasm. These pathologic findings in the appropriate clinical setting should serve to alert the pathologist to the possibility of a DICER1-associated neoplasm and initiate appropriate testing on the neoplasm and to alert the clinician about the concern for a DICER1 mutation.

Melanoma secretion of transforming growth factor-ß2 leads to loss of epidermal AMBRA1 threatening epidermal integrity and facilitating tumour ulceration.

BACKGROUND: For patients with early American Joint Committee on Cancer (AJCC)-stage melanoma the combined loss of the autophagy regulatory protein AMBRA1 and the terminal differentiation marker loricrin in the peritumoral epidermis is associated with a significantly increased risk of metastasis. OBJECTIVES: The aim of the present study was to evaluate the potential contribution of melanoma paracrine transforming growth factor (TGF)-ß signalling to the loss of AMBRA1 in the epidermis overlying the primary tumour and disruption of epidermal integrity. METHODS: Immunohistochemistry was used to analyse AMBRA1 and TGF-ß2 in a cohort of 109 AJCC all-stage melanomas, and TGF-ß2 and claudin-1 in a cohort of 30 or 42 AJCC stage I melanomas, respectively, with known AMBRA1 and loricrin (AMLo) expression. Evidence of pre-ulceration was analysed in a cohort of 42 melanomas, with TGF-ß2 signalling evaluated in primary keratinocytes. RESULTS: Increased tumoral TGF-ß2 was significantly associated with loss of peritumoral AMBRA1 (P < 0·05), ulceration (P < 0·001), AMLo high-risk status (P < 0·05) and metastasis (P < 0·01). TGF-ß2 treatment of keratinocytes resulted in downregulation of AMBRA1, loricrin and claudin-1, while knockdown of AMBRA1 was associated with decreased expression of claudin-1 and increased proliferation of keratinocytes (P < 0·05). Importantly, we show loss of AMBRA1 in the peritumoral epidermis was associated with decreased claudin-1 expression (P < 0·05), parakeratosis (P < 0·01) and cleft formation in the dermoepidermal junction (P < 0·05). CONCLUSIONS: Collectively, these data suggest a paracrine mechanism whereby TGF-ß2 causes loss of AMBRA1 overlying high-risk AJCC early-stage melanomas and reduced epidermal integrity, thereby facilitating erosion of the epidermis and tumour ulceration.

A Summary of the Inaugural WHO Classification of Pediatric Tumors: Transitioning from the Optical into the Molecular Era.

Pediatric tumors are uncommon, yet are the leading cause of cancer-related death in childhood. Tumor types, molecular characteristics, and pathogenesis are unique, often originating from a single genetic driver event. The specific diagnostic challenges of childhood tumors led to the development of the first World Health Organization (WHO) Classification of Pediatric Tumors. The classification is rooted in a multilayered approach, incorporating morphology, IHC, and molecular characteristics. The volume is organized according to organ sites and provides a single, state-of-the-art compendium of pediatric tumor types. A special emphasis was placed on "blastomas," which variably recapitulate the morphologic maturation of organs from which they originate. SIGNIFICANCE: In this review, we briefly summarize the main features and updates of each chapter of the inaugural WHO Classification of Pediatric Tumors, including its rapid transition from a mostly microscopic into a molecularly driven classification systematically taking recent discoveries in pediatric tumor genomics into account.

Phenotypic similarities within the morphologic spectrum of DICER1-associated sarcomas and pleuropulmonary blastoma: Histopathologic features guide diagnosis in the LMIC setting.

Extrapulmonary DICER1-associated sarcomas (DS) can harbor morphological features overlapping with pleuropulmonary blastoma. We report three children with intracranial and genital tract sarcomas, suspected to have DS based on a heterogeneous yet defining combination of spindle-cell sarcomatous and blastemal morphology, with rhabdomyomatous differentiation. Foci of immature cartilage at diagnosis (n = 2/3) and increased neuroepithelial differentiation at recurrence (n = 1) were noted. Morphological suspicion prompted somatic testing at reference centers, confirming likely biallelic, loss-of-function, and "hotspot" missense DICER1 variants in all three tumors. This can serve as a model for this diagnosis in resource-limited settings and has implications for germline testing, surveillance, and tumor management.

DICER1-associated hepatic cystic neoplasm with pleuropulmonary blastoma-like features: a novel clinicopathologic diagnosis.

This report documents a unique multicystic neoplasm of the liver in an 8-month-old boy with a heterozygous germline pathogenic DICER1 variant. This neoplasm, initially considered most likely a mesenchymal hamartoma based on imaging, demonstrated the characteristic histologic pattern of embryonal rhabdomyosarcoma residing in the subepithelial or cambium layer-like zone of the epithelial-lined cysts. Thus, although the differential diagnosis includes mesenchymal hamartoma, a young child with a multicystic mass lesion in the liver, lung, or kidney should both raise the possibility of a germline pathogenic DICER1 variant and also not be mistaken for one of the other hepatic neoplasms of childhood.

Thoracic Sertoli-Leydig cell tumor: An alternative type of pleuropulmonary blastoma associated with DICER1 variation.

A 2-year-old boy presented with a large cystic and solid chest mass arising from the lung, radiographically consistent with pleuropulmonary blastoma (PPB). He underwent right lower lobectomy with resection of a well-circumscribed, mixed solid and cystic mass. The solid areas were composed of cords and nests of tumor cells in the myxoid stroma and retiform foci whose pathologic and immunophenotypic findings were consistent with a sex cord-stromal tumor with features of a Sertoli-Leydig cell tumor. Tumor testing showed a pathogenic variant in the DICER1 RNase IIIb hotspot domain. Family history was suggestive of DICER1 germline pathogenic DICER1 variation in absence of a detectable germline variant. He received 12 cycles of chemotherapy with ifosfamide, vincristine, dactinomycin and doxorubicin (IVADo) and surgery with complete response. One year after completion of chemotherapy, imaging studies showed concern for recurrence confirmed by thorascopic biopsy of a pleural-based mass. He is currently receiving cisplatin-based chemotherapy with reduction in tumor size. Review of the literature showed no similar cases; however, review of our pathology files revealed a single similar case of anterior mediastinal Sertoli cell tumor in a 3-year-old girl.

Programmed Death Ligand 1 Expression and Related Markers in Pleuropulmonary Blastoma.

INTRODUCTION: Pleuropulmonary blastoma (PPB), a rare childhood neoplasm of the lung, is linked to pathogenic DICER1 variants. We investigated checkpoint inhibitor markers including Programmed Death Ligand 1 (PD-L1), PD1, CD8 and tumor mutational burden (TMB) in PPB. MATERIAL AND METHODS: Cases were collected from departmental archives and the International PPB/DICER1 Registry. Immunohistochemistry (IHC) for PD-L1, PD-1, CD8 and DNA mismatch repair (MMR) genes were performed. In addition, normal-tumor paired whole exome sequencing (WES) was performed in two cases. RESULTS: Twenty-five PPB cases were studied, consisting of Type I (n = 8, including 2 Ir), Type II (n = 8) and Type III (n = 9). PD-L1 combined positive score (CPS) of 1, 4 and 80 was seen in three (3/25, 12.0%) cases of Type II PPB with negative staining in the remaining cases. PD-1 and CD8 stains demonstrated positive correlation (P < .05). The density of PD1 and CD8 in the interface area was higher than within tumor (P < .05). The MMR proteins were retained. TMB was 0.65 mutations/Mb in type II PPB with high expression of PD-L1, and 0.94 mutations/Mb in one negative PD-L1 case with metastatic tumor. CONCLUSION: A small subpopulation of PPB patient might benefit from checkpoint immunotherapy due to positive PD-L1 staining.

Human muscle stem cells are refractory to aging.

Age-related loss of muscle mass and strength is widely attributed to limitation in the capacity of muscle resident satellite cells to perform their myogenic function. This idea contains two notions that have not been comprehensively evaluated by experiment. First, it entails the idea that we damage and lose substantial amounts of muscle in the course of our normal daily activities. Second, it suggests that mechanisms of muscle repair are in some way exhausted, thus limiting muscle regeneration. A third potential option is that the aged environment becomes inimical to the conduct of muscle regeneration. In the present study, we used our established model of human muscle xenografting to test whether muscle samples taken from cadavers, of a range of ages, maintained their myogenic potential after being transplanted into immunodeficient mice. We find no measurable difference in regeneration across the range of ages investigated up to 78 years of age. Moreover, we report that satellite cells maintained their myogenic capacity even when muscles were grafted 11 days postmortem in our model. We conclude that the loss of muscle mass with increasing age is not attributable to any intrinsic loss of myogenicity and is most likely a reflection of progressive and detrimental changes in the muscle microenvironment such as to disfavor the myogenic function of these cells.

Expression of p53 is significantly associated with recurrence-free survival and overall survival in pleuropulmonary blastoma (PPB): a report from the International Pleuropulmonary Blastoma/DICER1 Registry.

Pleuropulmonary blastoma (PPB) is a primary embryonal malignancy of childhood that is characterized by distinct morphologic types: type Ir (regressed), type I (cystic), type II (cystic and solid), and type III (solid). Prognosis varies by PPB type. Most cases are associated with a germline pathogenic mutation in DICER1; however, there is limited data on the factor(s) at a cellular level that drive progression from type I to type III. In this study, we evaluated the expression of p53 and its prognostic implications. A total of 143 PPB cases were included in the study with the following distribution in PPB types: Ir (14%), I (23%), II (32%), and III (31%). P53 expression by immunohistochemistry (IHC) was recorded as four groups: 0%, 1-25%, 26-75%, and 76-100%. All type I PPBs showed 0-25% p53 expression compared to the higher p53 expression (>25%) in type III PPB (p < 0.0001), to support the argument that p53 has a role in tumor progression. In addition, type Ir with the architectural hallmarks of type I PPB, but lacking the primitive cell population, has negligible p53 expression. High p53 expression (staining observed in >25% of the tumor cells) was significantly associated with age over 1 year (p = 0.0033), neoadjuvant therapy (p = 0.0009), positive resection margin (p = 0.0008) and anaplasia (p < 0.0001). P53 expression was significantly associated with recurrence-free survival (p < 0.0001) and overall survival (p = 0.0350), with higher p53 expression associated with worse prognosis. Comparisons of concordance statistics showed no significant difference in prognostication when using morphologic types compared to p53 expression groups (p = 0.647). TP53 sequence was performed in 16 cases; the most common variant identified was a missense variant (12 cases), and in one case a frameshift truncating variant was noted. Based on these findings, we recommend performing p53 IHC in all newly diagnosed cases of types II and III PPB to further aid in risk stratification.