Evaluation of bone pathology within the head and neck region, particularly the gnathic bonesis is complex, demonstrating unique pathologic processes. In part, this variation is due to odontogenesis and the embryological cells that may be involved, which can contribute to disease development and histologic variability. As with any boney pathosis, the key is to have clinical correlation, particularly with radiographic imaging prior to establishing a definitive diagnosis. This review will cover those entities that have a predilection for the pediatric population, and while it is not all inclusive, it should serve as a foundation for the pathologist who is evaluating bony lesions involving the craniofacial skeleton.

Cysts encountered in the head and neck typically arise from epithelium that would normally be programmed to form teeth or tooth-supporting structures (odontogenic epithelium). These cysts come with a confusing array of similar-sounding names and histopathologic features that are sometimes shared between conditions. Here we describe and contrast the relatively-common lesions: hyperplastic dental follicle, dentigerous cyst, radicular cyst, buccal bifurcation cyst, odontogenic keratocyst, glandular odontogenic cyst, and the less-common gingival cyst of the new-born and thyroglossal duct cyst. The goal of this review is to help clarify and simplify these lesions for the general pathologist, pediatric pathologist, and surgeon.

Restricted accessAbstractFirst published online April 1, 2023Society for Pediatric Pathologists Abstracts of the 2023 Spring Meeting March 10-11, 2023 Hybrid MeetingVolume 26, Issue 2https://doi.org/10.1177/10935266231164021

MYCN gene amplification is a powerful indicator of poor prognosis of neuroblastoma patients. However, MYCN non-amplified patients still showed heterogeneity in survival outcome. This study aimed to investigate the prognostic role of MYCN immunohistochemistry (IHC) in pre-treatment and post-treatment neuroblastoma tumors. 215 untreated neuroblastoma tumors were stained with anti-MYCN antibody by immunohistochemical staining. 22 post-treatment tumors were used to compare MYCN staining with paired pre-treatment samples. Results were analyzed with other prognostic indicators. Moderate or strong expression of MYCN was associated with unfavorable survival outcomes (P < .001). Prominent staining of MYCN IHC was 95% sensitive and 95% specific for the presence of MYCN gene amplification in this study. Ten of 214 (5%) patients showed prominent MYCN staining but MYCN non-amplification, and had a poor prognosis (29.6 ± 16.4%, 5-year overall survival). Most of cases (7/11, 64%) with high or moderate MYCN expression before chemotherapy showed lower expression in their tumors after chemotherapy. MYCN protein overexpression was not only a sensitive and specific marker for MYCN gene amplification, but also a marker of poor prognosis in patients without MYCN amplification. However, MYCN protein expression was not always consistent before and after treatment.

Papillary intralymphatic angioendothelioma (PILA) is an extremely rare vascular tumor and its pathogenesis is unknown. Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-related overgrowth spectrum (PROS) is a heterogeneous group of disorders caused by mosaicism for activating mutations of PIK3CA and characterized by asymmetric overgrowth, skeletal anomalies, skin lesions, and vascular malformations. An association between PILA and PROS has not been known. We report a case of PILA involving the spleen of a young girl with the clinical and molecular diagnosis of PROS. Sequencing of the patient's germ-line DNA detected a pathogenic PIK3CA variant c.1357G>A in 10.6% of alleles. Splenectomy revealed a 4-cm tumor composed of ectatic lymphatics with intraluminal papillary projections, consistent with PILA. The tumor cells showed immunohistochemical expression of CD31, CD34, ERG, FLI-1, PROX1, and caldesmon, while D2-40 was negative. The latter may suggest that the tumor derived from an endothelial precursor arrested in the final steps of lymphothelial differentiation, in keeping with the known role of the PIK3CA-governed molecular pathway in the progression of vascular progenitors to mature endothelial cells. The data implicates PIK3CA in the pathogenesis of PILA and broadens the spectrum of phenotypic expressions of PROS.

Congenital disorders of glycosylation (CDG) are associated with ciliary dysfunction due to altered glycosylation of ciliary glycoproteins. We describe a severe ciliopathy-like phenotype in a female infant associated with a novel homozygous missense variant NM_004870.4(MPDU1):c.503G>A/p.Gly168Glu. Our findings, based on the co-segregation of the variant with the phenotype and in-silico analysis, implicate this MPDU1 missense variant in this disorder. Matched phenotype includes symmetric growth restriction, facial dysmorphism, ichthyosis, hepatomegaly with severe duct plate malformation, renal cortical tubular and glomerular cysts, moderate cerebral tetraventricular dilatation, and severe pontocerebellar hypoplasia. According to this observation, CDG should be included in the workup of infantile ciliopathy-like disorder.

To establish the incidence of "diabetes-related death" (DRD) in children with known and unknown Diabetes Mellitus (DM) dying unexpectedly, and describe post-mortem (PM) biochemistry findings. PM reports from the previous 16-year period were reviewed. Cases of DRD were extracted. All available demographic, clinical, and autopsy data including laboratory analyses was retrieved. 9/1376 (0.7%) DRD cases were identified. This was attributed to Diabetic Ketoacidosis in 7 and to Death in Bed Syndrome in 2. 4/9 cases were known diabetic and on insulin; whilst in 5/9 cases the diagnosis of DM was at PM. The mean age was 11.6 years (range 2.5-15). At PM, 4 cases were undernourished. The histology demonstrated pancreatic changes in keeping with DM in 3/9 and unremarkable pancreatic findings in 6/9. 3 cases also had autoimmune thyroiditis (1 also had myocarditis and Armanni-Ebstein nephropathy). Toxicological and biochemical analysis showed raised: β-hydroxybutyrate in 6, ketone bodies in 5 cases and raised HbA1c in 3c. Type 1 DM is an infrequent but yet potentially preventable cause of death in children. Our findings highlight the value of routine biochemical and toxicological analysis in all PM examinations of infants and children dying suddenly and unexpectedly.

Mucosal biopsies in eosinophilic esophagitis (EoE) can exhibit lamina propria (LP) fibrosis, which may portend stenotic complications; however, the histologic diagnosis of LP fibrosis is subjective. We sought to assess and improve the consistency of LP fibrosis diagnosis among our pathologist group. At a large pediatric hospital, 25 esophageal biopsy slides from 19 patients (16 with EoE) exhibiting a wide spectrum of LP area, artifacts, and fibrosis severity were scanned into whole-slide images. Staff pediatric pathologists (n = 8) separate from the authors classified each biopsy by LP adequacy and fibrosis severity 1 month before and after completion of an educational tutorial. Consensus was defined as >70% agreement. At baseline, 16/25 (64%) cases reached consensus for no fibrosis (n = 3), fibrosis (n = 7), or inadequate LP (n = 6); agreement was fair (α = 0.34). Post-tutorial, 13/25 (52%) cases reached consensus for no fibrosis (n = 2), fibrosis (n = 7), or inadequate LP (n = 4); agreement was again fair (α = 0.33). There was moderate agreement in grading of fibrosis severity (α = 0.54). We document only fair-to-moderate agreement in the diagnosis of esophageal LP fibrosis and adequacy in a large pediatric pathologist group despite targeted education, highlighting a challenge in incorporating this feature into EoE research and clinical decision-making.