Dina El Demellawy

Congenital mesoblastic nephroma: a study of 19 cases using immunohistochemistry and ETV6-NTRK3 fusion gene rearrangement

Mesoblastic nephroma (MN) is the most common renal tumour in the first 3 months of life and accounts for 3-5% of all paediatric renal neoplasms. To further understand the morphological variants of MN, we identified 19 cases of MN (five classic, eight cellular and six mixed) and examined each case for markers known to be important in urogenital embryological development (PAX8, WT1 and RCC), stem cell associated markers (Oct 4, CD34 and c-kit), muscle/myofibroblastic markers (muscle specific actin, calponin and h-caldesmon), aberrant transcription factors, cell cycle regulation and other oncogenic proteins (p16, cyclin D1 and beta-catenin). Fluorescence in situ hybridisation (FISH) testing for ETV6-NTRK3 gene fusion/rearrangement revealed further differentiation between the subtypes with ETV6-NTRK3 gene fusion detected in 0/5 of the classic MN, 8/8 of the cellular MN and 5/6 of the mixed MN cohorts, respectively. Our results conclude that cyclin D1 and beta-catenin may be useful markers for differentiating between cellular MN and classic MN when the histology is not conclusive. The absence of expression of stem cell markers and markers involved in urogenital development suggests that MN is not a nephroma and most likely represents a soft tissue tumour, with congenital infantile fibrosarcoma representing cellular MN with a predilection to arise in the kidney. In addition, the immunophenotype and genetic fingerprint of mixed MN most likely represents a heterogenous group of tumours that are mostly cellular type, with areas that are phenotypically less cellular.

Methylation status of the chromosome arm 19q MicroRNA cluster in sporadic and androgenetic-Biparental mosaicism-associated hepatic mesenchymal hamartoma.

The C19MC gene on chromosome band 19q13.4 encodes a cluster of 46 microRNAs; those microRNAs are normally only expressed from the paternal allele and in the placenta. Placental expression correlates with selective demethylation of the paternal C19MC promoter, in contrast to methylation of both maternal and paternal alleles in nonplacental tissues. Prior investigations demonstrated “ectopic” activation of this gene in most hepatic mesenchymal hamartomas, including sporadic tumors and others with androgenetic-biparental mosaicism (subset of cells are diploid, but contain only paternally derived chromosomes). In the present investigation of C19MC promoter methylation status in a series of 14 mesenchymal hamartomas, a demethylated allele was identified in 6 tumors, including all 4 with androgenetic-biparental mosaicism. Conversely, only methylated alleles were cloned from sporadic hamartomas, including 3 tumors with chromosomal rearrangements thought likely to activate C19MC expression independent of the native promoter. In conjunction with published data, the findings suggest multiple molecular mechanisms for C19MC activation in hepatic mesenchymal hamartoma, including the existence of a normal placental imprinting pattern in mesenchymal cells in a subset of cases. Some or all of the latter hamartomas may result from placental “grafting,” a hypothesis supported by endothelial expression of the placental vascular marker, glucose transporter-1, in 1 of the 6 cases with a demethylated allele.

Value of histopathology for predicting the post-operative complications of ileo-anal anastomosis (J-pouch) procedure in children with refractory ulcerative colitis.

The J-pouch is a surgical procedure offered to children with refractory ulcerative colitis (UC) who have undergone subtotal colectomy to reconstruct a reservoir function with ileo-anal anastomosis. Unfortunately, post-operative complications may occur and can compromise the pouch function. We assessed rectal histopathology to determine whether severity of inflammation in the rectum prior to the creation of the J-Pouch was associated with post-operative complications. We retrospectively reviewed the histopathology of all J-pouch procedure specimens from paediatric patients during the period 2000-2013 using an objective grading system that assesses the chronicity and activity of the UC disease. We analysed the parameters for association with the post-operative complications. A classification tree algorithm was generated to predict the risk of complication based on histopathological parameters. A total of 28 paediatric patients were identified, among whom 10 developed post-operative complications (35%). The activity score at the recto-anal margin was higher among the patients with post-operative complications (mean 7.3±3.1 versus 4.8±3.1; p=0.04). The involvement of more than 5% colonic crypts with epithelial neutrophilic infiltration at the recto-anal margin was found to be an independent parameter that would stratify the patients into low-risk or high-risk group for developing complications (17% versus 64%; p=0.04). An association between UC disease activity at the recto-anal margin and post-operative J-pouch complications was determined. Potentially, this association suggests that a histopathological assessment of the recto-anal transitional zone may have value in guiding the surgeon on the risk of post-operative complications.

Does MAP2 have a Role in Predicting the Development of Anti-NMDAR Encephalitis Associated with Benign Ovarian Teratoma? A Report of Six New Pediatric Cases:

Anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis is a potentially fatal neurologic syndrome in which patients present with a spectrum of central nervous system deficits. Sixty percent of the cases can be attributed to the presence of tumors, most often ovarian teratomas. This report examines 6 pediatric patients who presented with neurologic deficits associated with the presence of such tumors. These cases illustrate a perplexing phenomenon, where benign teratomas could have a possible association with anti-NMDAR encephalitis. The purpose of this study was to compare the histology and immunohistochemistry of tumors associated with this syndrome to ovarian teratomas found in patients presenting with no neurologic symptoms. After obtaining institutional review board approval, 57 cases of ovarian teratomas were identified at our institution over 12 years. Six patients were identified with anti-NMDAR encephalitis. A panel of immunostains, including S100, GFAP, MAP2, and NeuN was applied to patients tumor sections as well as the 6 controls from age-matched patients. No qualitative histologic or immunohistochemical differences were seen between the study cases and control group. Because no qualitative differences were identified between the study cases and the control group, testing of paired serum and cerebrospinal fluid remains the best method for diagnosis of anti-NMDAR encephalitis. Tumor banking with molecular analysis of ovarian teratomas, including whole-genome sequencing and comparative genomic hybridization between ovarian tissue saved from patients with and without anti-NMDAR encephalitis, is necessary to fully understand the etiopathogenesis of anti-NMDAR encephalitis.

Idiopathic Intervertebral Disc Calcification in Childhood: An Atypical Case of an Uncommon Entity for Pediatric Pathologists

Calcification of the intervertebral disc is a common occurrence in the adult population, but it is rare in children. However, its radiological and clinical findings are well described in the pediatric age group, with close to 150 publications on record. In contrast, little information is available regarding the histological features of this entity, which may prove to be challenging to surgical pathologists. Here we provide a detailed description of a young patient with an inflammatory retropharyngeal mass originating in a calcified intervertebral disc. A review of the pathological features described in the literature in English, with pathogenic considerations, is presented.

Early Onset Allergic Proctitis in a Preterm Neonate—A Case Report and Review of the Literature

Cow’s milk protein allergy/intolerance (CMPA/CMPI) is a common entity in the pediatric population with a nonspecific presentation ranging from gastrointestinal symptoms to systemic manifestations. Most infants with CMPI are term, and symptoms often appear in the week following the introduction of cow’s milk-based formula. There is typically a significant delay in the onset of milk allergy in premature infants compared to full term. We report a rare case of a premature neonate who presented with symptoms of CMPA within the first 2 days of life.

Rickets: Historical, Epidemiological, Pathophysiological, and Pathological Perspectives

Rickets was a common metabolic disease of bone a century ago in Europe, North America, and East Asia (mainly due to vitamin D deficiency) but was largely eradicated in growing children by use of cod liver oil and the introduction of vitamin D fortification of milk in the 1930s in the United States. Vitamin D deficiency (VDD) remains the most common form of metabolic bone disease that is entirely preventable and treatable. Historically, rickets has appeared in sporadic epidemics and, despite the introduction of numerous preventive strategies, VDD has remained a global health problem amongst children. Moreover, developed countries such as Canada, Australia, the United Kingdom, and the United States have not been exempt from this. The radiological and histological features of rickets are both distinctive and characteristic and they reflect the underlying pathophysiological issue of decreased mineralization of bone as a result of VDD. The radiological features include 1) metaphyseal cupping and fraying, 2) poor mineralization of epiphyseal centers, 3) irregular and widened epiphyseal plates, 4) increased distance between the end of shaft and epiphyseal center, 5) cortical spurs at right angles to the metaphysis, 6) coarse trabeculation, and 7) periosteal reactions. Fractures may also be evident. The histological features of rickets reflect the failure of cartilage to mineralize and undergo resorption. This results in 1) disordered proliferation of chondrocytes in the hypertrophic zone secondary to a lack of apoptosis, 2) loss of the columnar arrangement of chondrocytes that results in thickening and disorganization of the hypertrophic zone, 3) tongue-like projections of cartilage that extend into the spongiosa, 4) irregularity of the limit between the proliferative and hypertrophic zones, and 5) penetration of blood vessels into the hypertrophic zone. The case of a premature 3-month-old female infant, born in the winter months in the arctic region of Canada who died from a lobar pneumonia with an incidental finding of radiological and pathological evidence of rickets, is presented. The case is used to review the entity of rickets from historical, pathophysiological, radiological, and histological perspectives.

Color image processing in Hirschsprung's disease diagnosis

Hirschsprungs disease is a gut motility disorder, which can affect newborns and children, characterized by absent ganglion cells within the rectum or colorectum. Surgical intervention involves a pull-through operation, connecting ganglionic segments together after excising the aganglionic segment. Subjective examination of seromuscular biopsies and resected segment for ganglion cells by a pathologist is the standard of care for Hirschsprungs patients. This paper explores the feasibility of an objective approach using multistage color image processing to segment the muscularis propria, identify regions of interest within, separate plexuses in the regions of interest, and detect and quantify ganglion cells within individual plexuses. Results observed on one test case showed that this multistage approach was able to segment muscularis propria with results comparable to manual segmentation at 77.3% region-coincidence. Regions of interest were identified with 100% accuracy, all containing at least one plexus, with 0 false negatives. Automatic plexus segmentation had a precision of 88.5% and recall of 90.2%. Automated ganglion detection achieving a precision of 85.7% and recall of 72.0%. Preliminary results are encouraging but performance needs improvement. The main issues encountered is the varying colour contrast within an image and the use of an imperfect feature set for classification.

Neurogenic Ovarian Cyst--A Rare, Monodermal Teratoma.

To the Editor, Monodermal teratomas (MNs) are a subtype of teratomas with tissue derived from only a single germ line. Other than struma ovarii, MNs composed of other mature tissues are exceedingly rare. A 10-year-old girl presented with a urinary tract infection. Abdominal ultrasound revealed a large, fluidfilled mass (Fig. 1), initially interpreted as a distended bladder. However, catheterization failed to relieve the mass. An abdominal computed tomography scan showed a right ovarian cyst (7.9 3 6.7 3 5.2 cm), which was percutaneously drained. She underwent a laparoscopic cystectomy for removal of the entire cyst. Grossly, the tissue of the multiple tan and brown, rubbery cyst wall measured from 1.2 3 0.9 3 0.4 cm to 6 3 2.5 3 0.3 cm. Histologically, the cyst showed mature central nervous system (CNS) tissue with ribbons of neuroglial tissue with astrocytes, occasional Rosenthal fibers, oligodendrocytes, ependymal cells (EC), and a few scattered neurons with an overlying arachnoid layer (Fig. 2). Cerebellar components with a molecular layer, internal granular cell layer, and Purkinje cells (Fig. 2, inset) were identified. Rare choroid plexus elements were noted. No native ovarian parenchyma, nonneurogenic tissues, or immature elements were present. The striking organoid nature of this tumor was further characterized by immunohistochemistry (IHC) (Table 1). Strong staining for glial fibrillary acidic protein (GFAP) confirmed the presence of a dense, fibrillary, astrocytic background. Arachnoid-covering cells were outlined with vimentin and epithelial membrane antigen (EMA), the latter also outlining the apical surface of the ependymal cells. Both neurofilament (NF) and NeuN highlighted mature neurons in the remnants of the cortex, the small neurons of the cerebellar internal granular layer, and the Purkinje cells. Protein Gene Product (PGP) 9.5 was positive in the few axonal processes present and showed a peculiar cross-reaction with ependymal cells.