Feeding mode influences dynamic gut microbiota signatures and affects susceptibility to anti-CD3 mAb-induced intestinal injury in neonatal mice.

Feeding modes influence the gut microbiome, immune system, and intestinal barrier homeostasis in neonates; how feeding modes impact susceptibility to neonatal gastrointestinal (GI) diseases is still uncertain. Here, we investigated the impact of dam feeding (DF) and formula feeding (FF) on features of the gut microbiome and physiological inflammation during the first 2 days of postnatal development and on the susceptibility to intestinal injury related to the inflammatory state in neonatal mouse pups. 16S rRNA sequencing data revealed microbiome changes, lower α-diversity, and a distinct pattern of ß-diversity including expansion of f_Enterobacteriaceae and f_Enterococcaceae in the ileum of FF pups compared with DF pups by postnatal day (P)2. Together with gut dysbiosis, the FF cohort also had greater ileal mucosa physiological inflammatory activity compared with DF pups by P2 but maintained normal histological features. Interestingly, FF but not DF mouse pups developed necrotizing enterocolitis (NEC)-like intestinal injury within 24 h after anti-CD3 mAb treatment, suggesting that FF influences the susceptibility to intestinal injury in neonates. We further found that NEC-like incidence in anti-CD3 mAb-treated FF neonatal pups was attenuated by antibiotic treatment. Collectively, our data suggest that FF predisposes mouse pups to anti-CD3 mAb-induced intestinal injury due to abnormal f_Enterobacteriaceae and f_Enterococcaceae colonization. These findings advance our understanding of FF-associated microbial colonization and intestinal inflammation, which may help inform the development of new therapeutic approaches to GI diseases like NEC in infants.NEW & NOTEWORTHY This report shows that a feeding mode profoundly affects gut colonization in neonatal mice. Furthermore, our results demonstrate that formula feeding predisposes mouse pups to anti-CD3 mAb-induced necrotizing enterocolitis (NEC)-like intestinal injury upon inadequate microbial colonization. The study suggests the role of the combined presence of formula feeding-associated dysbiosis and mucosal inflammation in the pathogenesis of NEC and provides a new mouse model to study this disease.

Blocking NF-κB Activation in Ly6c+ Monocytes Attenuates Necrotizing Enterocolitis.

Necrotizing enterocolitis (NEC) is a devastating disease affecting premature infants with intestinal inflammation and necrosis. The neonatal intestinal inflammatory response is rich in macrophages, and blood monocyte count is low in human NEC. We previously found that NF-κB mediates the intestinal injury in experimental NEC. However, the role of NF-κB in myeloid cells during NEC remains unclear. Herein, inhibitor of kappaB kinase ß (IKKß), a critical kinase mediating NF-κB activation, was deleted in lysozyme M (Lysm)-expressing cells, which were found to be Cd11b+Ly6c+ monocytes but not Cd11b+Ly6c- macrophages in the dam-fed neonatal mouse intestine. NEC induced differentiation of monocytes into intestinal macrophages and up-regulation of monocyte recruitment genes (eg, L-selectin) in the macrophage compartment in wild-type mice, but not in pups with IKKß deletion in Lysm+ cells. Thus, NF-κB is required for NEC-induced monocyte activation, recruitment, and differentiation in neonatal intestines. Furthermore, pups with Lysm-IKKß deletion had improved survival and decreased incidence of severe NEC compared with littermate controls. Decreased NEC severity was not associated with an improved intestinal barrier. In contrast, NEC was unabated in mice with IKKß deletion in intestinal epithelial cells. Together, these data suggest that recruitment of Ly6c+ monocytes into the intestine, NF-κB activation in these cells, and differentiation of Ly6c+ monocytes into macrophages are critical cellular and molecular events in NEC development to promote disease.

In Inflamed Intestinal Tissues and Epithelial Cells, Interleukin 22 Signaling Increases Expression of H19 Long Noncoding RNA, Which Promotes Mucosal Regeneration.

BACKGROUND & AIMS: Inflammation affects regeneration of the intestinal epithelia; long noncoding RNAs (lncRNAs) regulate cell functions, such as proliferation, differentiation, and migration. We investigated the mechanisms by which the lncRNA H19, imprinted maternally expressed transcript (H19) regulates regeneration of intestinal epithelium using cell cultures and mouse models of inflammation. METHODS: We performed RNA-sequencing transcriptome analyses of intestinal tissues from mice with lipopolysaccharide (LPS)-induced sepsis to identify lncRNAs associated with inflammation; findings were confirmed by quantitative real-time polymerase chain reaction and in situ hybridization analyses of intestinal tissues from mice with sepsis or dextran sulfate sodium (DSS)-induced mucosal wound healing and patients with ulcerative colitis compared to healthy individuals (controls). We screened cytokines for their ability to induce expression of H19 in HT-29 cells and intestinal epithelial cells (IECs), and confirmed findings in crypt epithelial organoids derived from mouse small intestine. IECs were incubated with different signal transduction inhibitors and effects on H19 lncRNA levels were measured. We assessed intestinal epithelial proliferation or regeneration in H19ΔEx1/+ mice given LPS or DSS vs wild-type littermates (control mice). H19 was overexpressed in IECs using lentiviral vectors and cell proliferation was measured. We performed RNA antisense purification, RNA immunoprecipitation, and luciferase reporter assays to study functions of H19 in IECs. RESULTS: In RNA-sequencing transcriptome analysis of lncRNA expression in intestinal tissues from mice, we found that levels of H19 lncRNA changed significantly with LPS exposure. Levels of H19 lncRNA increased in intestinal tissues of patients with ulcerative colitis, mice with LPS-induced and polymicrobial sepsis, or mice with DSS-induced colitis, compared with controls. Increased H19 lncRNA localized to epithelial cells in the intestine, regardless of Lgr5 messenger RNA expression. Exposure of IECs to interleukin 22 (IL22) increased levels of H19 lncRNA with time and dose, which required STAT3 and protein kinase A activity. IL22 induced expression of H19 in mouse intestinal epithelial organoids within 6 hours. Exposure to IL22 increased growth of intestinal epithelial organoids derived from control mice, but not H19ΔEx1/+ mice. Overexpression of H19 in HT-29 cells increased their proliferation. Intestinal mucosa healed more slowly after withdrawal of DSS from H19ΔEx1/+ mice vs control mice. Crypt epithelial cells from H19ΔEx1/+ mice proliferated more slowly than those from control mice after exposure to LPS. H19 lncRNA bound to p53 and microRNAs that inhibit cell proliferation, including microRNA 34a and let-7; H19 lncRNA binding blocked their function, leading to increased expression of genes that promote regeneration of the epithelium. CONCLUSIONS: The level of lncRNA H19 is increased in inflamed intestinal tissues from mice and patients. The inflammatory cytokine IL22 induces expression of H19 in IECs, which is required for intestinal epithelial proliferation and mucosal healing. H19 lncRNA appears to inhibit p53 protein and microRNA 34a and let-7 to promote proliferation of IECs and epithelial regeneration.

Dissociation of hepatic insulin resistance from susceptibility of nonalcoholic fatty liver disease induced by a high-fat and high-carbohydrate diet in mice.

Liver steatosis in nonalcoholic fatty liver disease is affected by genetics and diet. It is associated with insulin resistance (IR) in hepatic and peripheral tissues. Here, we aimed to characterize the severity of diet-induced steatosis, obesity, and IR in two phylogenetically distant mouse strains, C57BL/6J and DBA/2J. To this end, mice (male, 8 wk old) were fed a high-fat and high-carbohydrate (HFHC) or control diet for 16 wk followed by the application of a combination of classic physiological, biochemical, and pathological studies to determine obesity and hepatic steatosis. Peripheral IR was characterized by measuring blood glucose level, serum insulin level, homeostasis model assessment of IR, glucose intolerance, insulin intolerance, and AKT phosphorylation in adipose tissues, whereas the level of hepatic IR was determined by measuring insulin-triggered hepatic AKT phosphorylation. We discovered that both C57BL/6J and DBA/2J mice developed obesity to a similar degree without the feature of liver inflammation after being fed an HFHC diet for 16 wk. C57BL/6J mice in the HFHC diet group exhibited severe pan-lobular steatosis, a marked increase in hepatic triglyceride levels, and profound peripheral IR. In contrast, DBA/2J mice in the HFHC diet group developed only a mild degree of pericentrilobular hepatic steatosis that was associated with moderate changes in peripheral IR. Interestingly, both C57BL/6J and DBA/2J developed severe hepatic IR after HFHC diet treatment. Collectively, these data suggest that the severity of diet-induced hepatic steatosis is correlated to the level of peripheral IR, not with the severity of obesity and hepatic IR. Peripheral rather than hepatic IR is a dominant factor of pathophysiology in nonalcoholic fatty liver disease.

Bifidobacteria stabilize claudins at tight junctions and prevent intestinal barrier dysfunction in mouse necrotizing enterocolitis.

Whether intestinal barrier disruption precedes or is the consequence of intestinal injury in necrotizing enterocolitis (NEC) remains unknown. Using a neonatal mouse NEC model, we examined the changes in intestinal permeability and specific tight-junction (TJ) proteins preceding NEC and asked whether these changes are prevented by administration of Bifidobacterium infantis, a probiotic known to decrease NEC incidence in humans. Compared with dam-fed controls, pups submitted to the NEC protocol developed i) significantly increased intestinal permeability at 12 and 24 hours (as assessed by 70-kDa fluorescein isothiocyanate-dextran transmucosal flux); ii) occludin and claudin 4 internalization at 12 hours (as assessed by immunofluorescence and low-density membrane fraction immunoblotting); iii) increased claudin 2 expression at 6 hours and decreased claudin 4 and 7 expression at 24 hours; and iv) increased claudin 2 protein at 48 hours. Similar results were seen in human NEC, with claudin 2 protein increased. In mice, administration of B. infantis micro-organisms attenuated increases in intestinal permeability, preserved claudin 4 and occludin localization at TJs, and decreased NEC incidence. Thus, an increase in intestinal permeability precedes NEC and is associated with internalization of claudin 4 and occludin. Administration of B. infantis prevents these changes and reduces NEC incidence. The beneficial effect of B. infantis is, at least in part, due to its TJ and barrier-preserving properties.

Rhabdoid carcinoma of anal canal: role of electron microscopy and immunohistochemistry in establishing lineage.

ABSTRACT Rhabdoid carcinoma is a high-grade carcinoma with rhabdoid features and it is different from rhabdoid tumors that are broadly defined as malignant neoplasms with rhabdoid cellular appearance found primarily in the pediatric population, but adult cases have been reported in many anatomic locations. To date, no cases of anal canal rhabdoid carcinoma have been reported in the adult or pediatric population. We are reporting the first case of anal canal rhabdoid carcinoma, found in a 75-year-old male. We utilized ultrastructural as well as immunohistochemical studies to arrive at our diagnosis. Ultrastructural studies demonstrated the intermediate filament congregating to impart a rhabdoid appearance to tumor cells, and cytokeratin intermediate filaments and short microvilli indicating nature of tumor as carcinoma. Immunohistochemical phenotype showed neoplastic cells were positive for vimentin, pan-cytokeratin AE1/3, p63 and D2-40, which supports the genesis of tumor from skin adnexa. Even in the modern era of surgical pathology that routinely utilizes immunohistochemistry and molecular studies, adequate use of electron microscopy to help pinpoint the diagnosis in challenging cases is important.

Scattered Crypt Intestinal Epithelial Cell Apoptosis Induces Necrotizing Enterocolitis Via Intricate Mechanisms.

BACKGROUND & AIMS: Necrotizing enterocolitis (NEC) is a life-threatening disease affecting mostly the ileum of preemies. Intestinal epithelial cell (IEC) apoptosis contributes to NEC pathogenesis. However, how scattered crypt IEC apoptosis leads to NEC with excessive villus epithelial necrosis remains unclear. METHODS: A novel triple-transgenic mouse model, namely, 3xTg-iAPcIEC (inducible apoptosis phenotype in crypt-IEC), was developed to induce IEC-specific overexpression of Fasl transgene using doxycycline (Dox)-inducible tetO-rtTA system and villin-cre technology. The 3-day-old neonatal 3xTg-iAPcIEC mice and their littermate controls were subcutaneously (s.c.) challenged with a single dose of Dox. Intestinal tissues were processed at different time points to examine scattered crypt IEC apoptosis-mediated NEC development. Gene knockout technology, antibody-mediated cell depletion, and antibiotic-facilitated Gram-positive bacteria depletion were used to study mechanisms. RESULTS: Treatment of 3xTg-iAPcIEC mouse pups with Dox induces scattered crypt IEC apoptosis followed by crypt inflammation and excessive villous necrosis resembling NEC. This progression correlated with elevated Ifng, Rip3, CD8+ T cells, and Gram-positive bacteria in the ileum. Mechanistically, IFN-γ and RIP3-activated signals mediate the effect of scattered crypt IEC apoptosis on the induction of intestinal crypt inflammation and villous necrosis. Meanwhile, pathophysiological events of CD8+ T cell infiltration and dysbiosis with Gram-positive bacteria primarily contribute to excessive villous inflammation and necrosis. Notably, blocking any of these events protects against NEC development in 3xTg-iAPcIEC mouse pups, underlining their central roles in NEC pathogenesis. CONCLUSIONS: Scattered crypt IEC apoptosis induces NEC in mouse pups via IFN-g, RIP3, CD8+ T cells, and Gram-positive bacteria-mediated comprehensive pathophysiological events. Our findings may advance knowledge in the prevention and treatment of NEC.

Melanoma in infants, caused by a gene fusion involving the anaplastic lymphoma kinase (ALK).

We describe the first cases of pediatric melanoma with ALK fusion gene arising within giant congenital melanocytic nevi. Two newborn boys presented with large pigmented nodular plaques and numerous smaller satellite nevi. Additional expansile nodules developed within both nevi and invasive melanomas were diagnosed before 10 months of age in both boys. Oncogenic driver mutations in NRAS and BRAF were absent in both cases. Instead, oncogenic ZEB2::ALK fusion genes were identified in both the nevus and melanoma developing within the nevus. In both cases, tumors were noted by ultrasound in utero, demonstrated significant nodularity at birth, and progressed to melanoma in the first year of life suggesting that congenital nevi with ALK fusion genes may behave more aggressively than those with other mutations. As ALK kinase inhibitors are effective against a range of tumors with similar ALK fusion kinases, identifying ALK fusion genes in congenital melanocytic nevi may provide an opportunity for targeted therapy.

Cytology-histology correlation of myoepithelial tumors harboring EWSR1-POU5F1 fusions: A report of two cases.

Myoepithelial tumors (MET) constitute a group of neoplasms with a variety of morphologic, immunophenotypic, and molecular features. Approximately half of MET of soft tissue harbor EWSR1 gene rearrangements with a subset showing EWSR1-POU5F1 fusions and demonstrating distinctive tendency towards aggressive behavior in children. Histologically, EWSR1-POU5F1-positive MET typically show clear-cell morphology with malignant features including marked pleomorphism and atypical mitotic figures. The cytomorphology of these tumors has not been well characterized. Reported here are the cytomorphologic features of two cases of EWSR1-POUF1-positive MET with histology correlation.

Milk fat globule-EGF factor 8 is a critical protein for healing of dextran sodium sulfate-induced acute colitis in mice.

Milk fat globule-EGF factor 8 (MFG-E8) has been shown to play an important role in maintaining the integrity of the intestinal mucosa and to accelerate healing of the mucosa in septic mice. Herein, we (a) analyzed the expression of MFG-E8 in the gut of wild-type (WT) C57BL/6 (MFG-E8(+/+)) mice with and without dextran sulfate sodium (DSS)-induced colitis, (b) characterized the pathological changes in intestinal mucosa of MFG-E8(+/+) and MFG-E8(-/-) mice with DSS-induced colitis and (c) examined the therapeutic role of MFG-E8 in inflammatory bowel disease by using DSS-induced colitis model. Our data documented that there was an increase in colonic and rectal MFG-E8 expression in MFG-E8(+/+) mice during the development of DSS colitis. MFG-E8 levels in both tissues decreased to below baseline during the recovery phase in mice with colitis. Changes in MFG-E8 gene expression correlated to the levels of inflammatory response and crypt-epithelial injury in both colonic and rectal mucosa in MFG-E8(+/+) mice. MFG-E8(-/-)mice developed more severe crypt-epithelial injury than MFG-E8(+/+) mice during exposure to DSS with delayed healing of intestinal epithelium during the recovery phase of DSS colitis. Administration of MFG-E8 during the recovery phase ameliorated colitis and promoted mucosal repair in both MFG-E8(-/-) and MFG-E8(+/+) mice, indicating that lack of MFG-E8 causes increased susceptibility to colitis and delayed mucosal healing. These data suggest that MGF-E8 is an essential protective factor for gut epithelial homeostasis, and exogenous administration of MFG-E8 may represent a novel therapeutic target in inflammatory bowel disease.

Identification of Differentially Expressed MicroRNAs in Osteosarcoma.

A limited number of reports have investigated the role of microRNAs in osteosarcoma. In this study, we performed miRNA expression profiling of osteosarcoma cell lines, tumor samples, and normal human osteoblasts. Twenty-two differentially expressed microRNAs were identified using high throughput real-time PCR analysis, and 4 (miR-135b, miR-150, miR-542-5p, and miR-652) were confirmed and validated in a different group of tumors. Both miR-135b and miR-150 have been previously shown to be important in cancer. We hypothesize that dysregulation of differentially expressed microRNAs may contribute to tumorigenesis. They might also represent molecular biomarkers or targets for drug development in osteosarcoma.

MFG-E8 Plays an Important Role in Attenuating Cerulein-Induced Acute Pancreatitis in Mice.

Milk fat globule-EGF factor 8 (MFG-E8) is a secreted glycoprotein that regulates tissue homeostasis, possesses potent anti-inflammatory properties, and protects against tissue injury. The human pancreas expresses MFG-E8; however, the role of MFG-E8 in the pancreas remains unclear. We examined the expression of MFG-E8 in the pancreas at baseline and during cerulein-induced acute pancreatitis in mice and determined whether MFG-E8 attenuates the progression of pancreatitis, a serious inflammatory condition that can be life-threatening. We administered cerulein to wild-type (WT) and Mfge8 knockout (KO) mice to induce pancreatitis. Immunoblot analysis showed that MFG-E8 is constitutively expressed in the murine pancreas and is increased in mice with cerulein-induced acute pancreatitis. In situ hybridization revealed that ductal epithelial cells in the mouse pancreas express Mfge8 transcripts at baseline. During pancreatitis, Mfge8 transcripts were abundantly expressed in acinar cells and endothelial cells in addition to ductal epithelial cells. Knocking out Mfge8 in mice exacerbated the severity of cerulein-induced acute pancreatitis and delayed its resolution. In contrast, administration of recombinant MFG-E8 attenuated cerulein-induced acute pancreatitis and promoted repair of pancreatic injury in Mfge8 KO mice. Taken together, our study suggests that MFG-E8 protects the pancreas against inflammatory injury and promotes pancreatic tissue repair. MFG-E8 may represent a novel therapeutic target in acute pancreatitis.

Glypican 3 has a higher sensitivity than alpha-fetoprotein for testicular and ovarian yolk sac tumour: immunohistochemical investigation with analysis of histological growth patterns.

AIMS: Glypican 3 (GPC3) has been reported to be overexpressed in yolk sac tumour (YST), but the sensitivity has not been compared with alpha-fetoprotein (AFP). YST can form numerous growth patterns and the expression of GPC3 in these patterns has not been studied. The aim was to address these aspects. METHODS AND RESULTS: Sections from testicular or ovarian YST were subjected to immunohistochemistry using GPC3 (n = 39) and AFP (n = 24). Overall immunoreactivity for each case and specific histological patterns were semiquantitatively evaluated (0-3+) and intensity of reactivity was scored (0-3). All cases expressed GPC3 (1+, 5%; 2+, 8%; 3+, 87%) with strong intensity (2.9). The majority expressed AFP (58%) but immunoreactivity was often focal (0, 42%; 1+, 33%; 2+, 25%) and intensity was low (1.0). Using GPC3, >75% of the microcystic (n = 38), macrocystic (n = 26), solid (n = 21), glandular-alveolar (n = 8), endodermal sinus (n = 7), polyvesicular vitelline (n = 5), enteric (n = 4) and micropapillary (n = 2) growth patterns displayed 2+ or 3+ positivity. CONCLUSIONS: YST can display a variety of growth patterns that can be confused with other germ cell tumour components. GPC3 detects all growth patterns tested and has a higher sensitivity for detecting YST than AFP.

High WT1 gene expression before haematopoietic stem cell transplant in children with acute myeloid leukaemia predicts poor event-free survival.

WT1 gene expression has been proposed as a useful marker of minimal residual disease in leukaemia. Its utility in paediatric haematopoietic stem cell transplantation (HSCT) has not been studied. We studied the prognostic value of WT1 expression in peripheral blood prior to HSCT in 36 children with acute myeloid leukaemia (AML). Samples were obtained 2 weeks pre-transplant to determine the level of WT1 expression. WT1 expression was normalized using K562 cells as a control and a relative value of 0.5 was chosen as the cut-off point between high and low WT1 expression. The median level of pre-transplant WT1 expression in the 36 patients was 0.09 (range 0.0001-11.0), with 11 patients having WT1 >or= 0.5 and 25, WT1 < 0.5. After HSCT, 76% of patients with high pre-transplant WT1 expression relapsed, in contrast to 0% of the patients with low WT1 expression. Those with high WT1 expression had significantly lower 5-year event-free survival (EFS) (18%, 95% CI 0-40%) as compared to those with low WT1 expression (68%, 95% CI 50-86%, P = 0.007). Multivariate analysis showed that pre-transplant WT1 level is the only significant prognostic factor for the difference in EFS. Our finding suggests that elevated WT1 gene expression before HSCT in paediatric AML predicts relapse and poor long-term EFS. A larger prospective study is warranted to compare the value of high WT1 expression and other markers of minimal residue disease in predicting clinical outcomes after HSCT.

Expression of glypican 3 in hepatoblastoma: an immunohistochemical study of 65 cases.

Glypican 3 is a heparin sulfate proteoglycan bound to the cell surface that is theorized to participate in cell signaling, resulting in embryonic cell growth and differentiation. The GPC3 gene is mutated in Simpson-Golabi-Behmel syndrome, whose features include numerous developmental abnormalities, tissue overgrowth, and an increased risk for embryonal malignancies, including hepatoblastoma. GPC3 has been detected in hepatic stem cells and was recently identified as one of the most overexpressed genes in hepatoblastoma by microarray analysis. The purpose of this study was to analyze the expression of GPC3 in a large series of hepatoblastoma using immunohistochemistry to assess its use as a diagnostic marker. The GPC3 immunoreactivity was semiquantitatively evaluated in 65 cases of hepatoblastoma. In addition, histologic patterns in each tumor were individually assessed for immunoreactivity. All 65 hepatoblastomas had cytoplasmic immunoreactivity for GPC3 with greater than 90% of cases showing strong, diffuse positivity. There was no reactivity in benign liver tissue. Fetal, embryonal, and small cell undifferentiated patterns were diffusely positive in almost all cases, whereas mesenchymal and teratoid patterns were nearly all negative. The high GPC3 expression consistently demonstrated in this study suggests that GPC3 may play a role in the tumorigenesis of hepatoblastoma.

Expression of glypican 3 in ovarian and extragonadal germ cell tumors.

Germ cell tumors (GCTs), rare malignancies that occur in a wide range of locations and display variable histologic patterns, may pose diagnostic challenges. Glypican 3 (GPC3), a membrane-bound heparan sulfate proteoglycan, has been shown to be a novel diagnostic marker in testicular GCT. However, GPC3 expression in ovarian and extragonadal GCT has not been reported. We evaluated GPC3 immunoreactivity in GCTs from 63 patients (57 children and 6 adults), including 14 ovarian and 20 extragonadal primary GCTs and 8 metastases along with 21 primary testicular GCTs for comparison. All 33 yolk sac tumors (YSTs) and both choriocarcinomas were immunoreactive for GPC3. In contrast, a minority of immature (4/10) and mature (4/35) teratomas were positive. No positivity was seen in 6 embryonal carcinomas or 5 germinomas. GPC3 is differentially expressed in ovarian and extragonadal GCTs, with expression predominantly observed in YSTs and choriocarcinoma.

Diffuse lung disease in young children: application of a novel classification scheme.

RATIONALE: Considerable confusion exists regarding nomenclature, classification, and management of pediatric diffuse lung diseases due to the relative rarity and differences in the spectrum of disease between adults and young children. OBJECTIVES: A multidisciplinary working group was formed to: (1) apply consensus terminology and diagnostic criteria for disorders presenting with diffuse lung disease in infancy; and (2) describe the distribution of disease entities, clinical features, and outcome in young children who currently undergo lung biopsy in North America. METHODS: Eleven centers provided pathologic material, clinical data, and imaging from all children less than 2 years of age who underwent lung biopsy for diffuse lung disease from 1999 to 2004. MEASUREMENTS AND MAIN RESULTS: Multidisciplinary review categorized 88% of 187 cases. Disorders more prevalent in infancy, including primary developmental and lung growth abnormalities, neuroendocrine cell hyperplasia of infancy, and surfactant-dysfunction disorders, constituted the majority of cases (60%). Lung growth disorders were often unsuspected clinically and under-recognized histologically. Cases with known surfactant mutations had characteristic pathologic features. Age at biopsy and clinical presentation varied among categories. Pulmonary hypertension, presence of a primary developmental abnormality, or ABCA3 mutation was associated with high mortality, while no deaths occurred in cases of pulmonary interstitial glycogenosis, or neuroendocrine cell hyperplasia of infancy. CONCLUSIONS: This retrospective cohort study identifies a diverse spectrum of lung disorders, largely unique to young children. Application of a classification scheme grouped clinically distinct patients with variable age of biopsy and mortality. Standardized terminology and classification will enhance accurate description and diagnosis of these disorders.

Serous Carcinoma of the Testicle and the Paratesticular Tissue: Case Report and Literature Review.

Ovarian-type epithelial lesions of the testicle and the paratesticular tissue are uncommon, especially invasive serous adenocarcinoma with only 18 cases reported in the literature. Although the majority of these tumors occur in adults with an age range from 16 to 87 years, only 1 patient was less than 10 years old. Herein, we report only the second case of invasive serous adenocarcinoma occurring in the first decade of life, that of a 7-year-old boy. Additionally, clinical presentation, imaging, histopathology, immunohistochemistry, and clinical follow-up of invasive serous adenocarcinoma of the testicle are discussed, along with a review of the literature.

Pathology of Melanotic Schwannoma.

CONTEXT.­: Melanotic schwannoma (MS) is a nerve sheath tumor with a uniform composition of variably melanin-producing Schwann cells and metastatic potential. The MS is an uncommon neoplasm, accounting for less than 1% of all nerve sheath tumors, with a predilection for spinal nerve involvement. Microscopically, the tumors are characterized by spindle and epithelioid cells arranged in interlacing fascicles, with marked accumulation of melanin in neoplastic cells and associated melanophages. The MSs are frequently associated with Carney complex, showing features of psammoma bodies and adipose-like cells. Strict criteria of malignancy in MS are not well developed, although a combination of worrisome histologic features (large, vesicular nuclei, with macronucleoli, brisk mitotic activity, and necrosis) raises concern for aggressive behavior. OBJECTIVE.­: To review the current status of the MS literature, discussing putative etiology, histopathology, current genetics, and differential diagnoses, including overlap with other pigmented tumors. DATA SOURCES.­: Search of PubMed (National Center for Biotechnology Information, Bethesda, Maryland) and the authors' own experiences. CONCLUSIONS.­: The occurrence of MS at several unusual anatomic sites and its spectrum of morphologic patterns can result in significant diagnostic difficulty, and correct diagnosis is particularly important because of its high tendency to recur locally and to metastasize, which highlights the importance of diagnostic recognition, ancillary molecular genetic testing, and close clinical follow-up of patients with MS.