D. Ashley Hill

Zika Virus Infection with Prolonged Maternal Viremia and Fetal Brain Abnormalities

The current outbreak of Zika virus (ZIKV) infection has been associated with an apparent increased risk of congenital microcephaly. We describe a case of a pregnant woman and her fetus infected with ZIKV during the 11th gestational week. The fetal head circumference decreased from the 47th percentile to the 24th percentile between 16 and 20 weeks of gestation. ZIKV RNA was identified in maternal serum at 16 and 21 weeks of gestation. At 19 and 20 weeks of gestation, substantial brain abnormalities were detected on ultrasonography and magnetic resonance imaging (MRI) without the presence of microcephaly or intracranial calcifications. On postmortem analysis of the fetal brain, diffuse cerebral cortical thinning, high ZIKV RNA loads, and viral particles were detected, and ZIKV was subsequently isolated.

Anaplastic lymphoma kinase (ALK) expression in the inflammatory myofibroblastic tumor: a comparative immunohistochemical study.

Inflammatory myofibroblastic tumor (IMT) is an uncommon mesenchymal neoplasm with a variable histologic appearance that may mimic other spindle cell processes, particularly nodular fasciitis, desmoid tumor, and in intra-abdominal locations, gastrointestinal stromal tumor. Recently, gene fusions involving ALK at chromosome 2p23 have been described in IMTs. The resultant ALK protein overexpression in the myofibroblastic component of these tumors is detectable by immunohistochemistry. We examined 73 IMTs, 20 cases of nodular fasciitis, 15 desmoid fibromatoses, and 15 gastrointestinal stromal tumors by immunohistochemistry using ALK-11, a rabbit polyclonal antibody that recognizes the C-terminus of the protein. ALK positivity was detected in 44 of 73 (60%) IMTs. All cases of nodular fasciitis, desmoid fibromatosis, and gastrointestinal stromal tumors were ALK negative (p < 0.001). These findings demonstrate that ALK positivity is common in IMTs, and immunohistochemistry using anti-ALK antibodies can be helpful in the differential diagnosis of these neoplasms. In addition, anti-ALK staining seems to correlate with those IMTs that have the typical tri-patterned histologic appearance and clinical presentation, providing additional support to the premise that IMT is a distinctive clinicopathologic entity within the broad category of inflammatory pseudotumors.

DICER1 Mutations in Familial Pleuropulmonary Blastoma

A rare form of lung cancer in children is associated with mutational disruption of an enzyme that generates small noncoding RNAs. Pleuropulmonary blastoma (PPB) is a rare pediatric lung tumor that is often part of an inherited cancer syndrome. PPBs consist of mesenchymal cells that are susceptible to malignant transformation and cysts lined by epithelial cells. In a subset of patients, overgrowth of the cysts by mesenchymal cells leads to sarcoma formation. Here, we show that 11 multiplex PPB families harbor heterozygous germline mutations in DICER1, a gene encoding an endoribonuclease critical to the generation of small noncoding regulatory RNAs. Expression of DICER1 protein was undetectable in the epithelial component of PPB tumors but was retained in the malignant mesenchyme (sarcoma). We hypothesize that loss of DICER1 in the epithelium of the developing lung alters the regulation of diffusible factors that promote mesenchymal proliferation.

Fusion of the ALK Gene to the Clathrin Heavy Chain Gene, CLTC, in Inflammatory Myofibroblastic Tumor

Inflammatory myofibroblastic tumor (IMT) is a rare, but distinctive mesenchymal neoplasm composed of fascicles of bland myofibroblasts admixed with a prominent inflammatory component. Genetic studies of IMTs have demonstrated chromosomal abnormalities of 2p23 and rearrangement of the anaplastic lymphoma kinase (ALK) gene locus. In a subset of IMTs, the ALK C-terminal kinase domain is fused with a tropomyosin N-terminal coiled-coil domain. In the current study, fusion of ALK with the clathrin heavy chain (CTLC) gene localized to 17q23 was detected in two cases of IMT. One of these cases exhibited a 2;17 translocation in addition to other karyotypic anomalies [46,XX,t(2;17)(p23;q23),add(16)(q24)].

Fusion of ALK to the Ran-binding protein 2 (RANBP2) gene in inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal proliferation of transformed myofibroblasts, with a prominent inflammatory cell component, that can mimic other spindle cell processes such as nodular fasciitis, desmoid tumor, and gastrointestinal stromal tumor. Genetic analyses have recently demonstrated rearrangements of anaplastic lymphoma kinase (ALK), located at 2p23, in a subset of IMTs. Molecular characterizations have identified ALK fusions involving tropomyosin‐3 and ‐4 (TPM‐3 and ‐4), the clathrin heavy chain (CLTC), and the cysteinyl‐tRNA synthetase (CARS) genes as fusion partners. Here we describe two IMTs with a novel ALK fusion that involves the Ran‐binding protein 2 (RANBP2) gene at 2q13, which normally encodes a large (358‐kDa) nucleopore protein localized at the cytoplasmic side of the nuclear pore complex. The N‐terminal 867 residues of RANBP2 are fused to the cytoplasmic segment of ALK in the 1,430–amino acid RANBP2‐ALK chimeric protein. Myofibroblasts that express RANBP2‐ALK exhibit nuclear membrane‐associated ALK staining that is unique compared to the subcellular localization observed with other ALK fusions in IMT, presumably attributable to heteroassociation of the fusion with normal RANBP2 at the nuclear pore. These findings expand the spectrum of ALK abnormalities observed in IMT and further confirm the clonal, neoplastic nature of these lesions.

Pulmonary cysts in early childhood and the risk of malignancy.

Surgery for congenital and early childhood lung cysts is often dictated by symptoms such as respiratory distress, infection or pneumothorax. Asymptomatic cysts present a therapeutic dilemma: surgical intervention and “conservative” observation have advocates. The risk of malignancy in such cysts is considered by some an indication for surgical intervention and is reviewed in this paper. Pleuropulmonary blastoma (PPB) is the most frequent malignancy associated with childhood lung cysts. Although rare, PPB occurs predictably in certain clinical and familial situations. This unique biology of PPB can inform the cyst management decision. The earliest manifestation of PPB is a malignant lung cyst in young children, clinically and radiographically indistinguishable from benign congenital lung cysts. Histopathologic examination differentiates cystic PPB from the benign cystic variants. Surgical excision of cystic PPB (with or without chemotherapy) cures approximately 85–90% of children. If not excised, cystic PPB evolves to cystic/solid or solid high‐grade sarcoma (cure rate 45–60%) by age 2–6 years. Numerous reports of “malignancy in a congenital lung cyst” are now understood as the characteristic progression of cystic PPB. PPB is genetically determined in many cases. Detailed family history may reveal the hallmarks of PPB in the patient or young relatives: a unique constellation of diseases including lung cysts, cystic nephroma, childhood cancers, stromal sex‐chord ovarian tumors, seminomas or dysgerminomas, intestinal polyps, thyroid hyperplasias, and hamartomas. Pneumothorax and multifocal/bilateral lung cysts also characterize PPB. These diagnoses predict that a lung cyst is more likely PPB than a benign congenital cyst. Patients fitting this pattern deserve histologic diagnosis. The genetic basis for this heritable syndrome is unknown but is being actively investigated. Pediatr Pulmonol. 2009; 44:14–30.

Genomic analysis of diffuse pediatric low-grade gliomas identifies recurrent oncogenic truncating rearrangements in the transcription factor MYBL1

Pediatric low-grade gliomas (PLGGs) are among the most common solid tumors in children but, apart from BRAF kinase mutations or duplications in specific subclasses, few genetic driver events are known. Diffuse PLGGs comprise a set of uncommon subtypes that exhibit invasive growth and are therefore especially challenging clinically. We performed high-resolution copy-number analysis on 44 formalin-fixed, paraffin-embedded diffuse PLGGs to identify recurrent alterations. Diffuse PLGGs exhibited fewer such alterations than adult low-grade gliomas, but we identified several significantly recurrent events. The most significant event, 8q13.1 gain, was observed in 28% of diffuse astrocytoma grade IIs and resulted in partial duplication of the transcription factor MYBL1 with truncation of its C-terminal negative-regulatory domain. A similar recurrent deletion-truncation breakpoint was identified in two angiocentric gliomas in the related gene v-myb avian myeloblastosis viral oncogene homolog (MYB) on 6q23.3. Whole-genome sequencing of a MYBL1-rearranged diffuse astrocytoma grade II demonstrated MYBL1 tandem duplication and few other events. Truncated MYBL1 transcripts identified in this tumor induced anchorage-independent growth in 3T3 cells and tumor formation in nude mice. Truncated transcripts were also expressed in two additional tumors with MYBL1 partial duplication. Our results define clinically relevant molecular subclasses of diffuse PLGGs and highlight a potential role for the MYB family in the biology of low-grade gliomas.

Ovarian sex cord-stromal tumors, pleuropulmonary blastoma and DICER1 mutations: A report from the International Pleuropulmonary Blastoma Registry

OBJECTIVE Pleuropulmonary blastoma (PPB) is a childhood cancer arising from pleuropulmonary mesenchyme. This neoplasm is a sentinel disease in a familial tumor syndrome recently found to be associated with germline mutations in DICER1. Observations of ovarian sex cord-stromal tumors (OSCST) in PPB kindreds led to further study. We sought to characterize ovarian tumors seen in probands and families with PPB and PPB-related conditions and define germline DICER1 status. METHODS Patient and family records of pathology-reviewed PPB cases enrolled in the International PPB Registry (IPPBR) were searched for ovarian tumors. Ovarian tumor pathology specimens were obtained and centrally reviewed. Germline DNA from patients with ovarian tumors was tested for DICER1 mutations. Three additional OSCST patients registered in the IPPBR were also tested for mutations in DICER1. RESULTS Among 296 kindreds including 325 children with PPB, we observed three children with both PPB and Sertoli-Leydig cell tumors (SLCT)/Sertoli cell tumors. Among family members of PPB patients, we identified six OSCST (three SLCT, one Sertoli cell tumor, one juvenile granulosa cell tumor, one gynandroblastoma). Age at ovarian tumor diagnosis was youngest in PPB probands and younger in family members than in OSCST in general. Germline DICER1 mutations were identified in four of six patients with OSCST from PPB kindreds and in two of three children with OSCST and no personal or family history of PPB. CONCLUSIONS Primary ovarian neoplasms, particularly OSCST, are a manifestation of the familial PPB syndrome and may be the initial clinical presentation of DICER1 mutations within a family.

Colorectal Carcinoma in Childhood and Adolescence : A Clinicopathologic Review

PURPOSE Pediatric colorectal carcinoma (CRC) is rare, but the available data suggest that it is more likely than adult CRC to be advanced at presentation and to have a poor outcome. We sought to better characterize pediatric CRC. PATIENTS AND METHODS We reviewed the clinical and pathologic features, prognostic factors, and outcome of CRC in 77 children and adolescents (ages 7 to 19 years) referred to St Jude Childrens Research Hospital between 1964 and 2003. RESULTS At presentation, 76 patients had one or more signs or symptoms of CRC (abdominal pain, altered bowel habits, weight loss, anemia). Tumors were evenly distributed between the right and left colon; 62% were mucinous adenocarcinoma. At presentation, 86% of patients had advanced-stage disease; more than half had distant metastases. Overall outcome was poor. Advanced stage and mucinous histology were significant predictors of adverse outcome. Stage-specific survival at 10 years was 67% +/- 27% (stage 1), 38% +/- 15% (stage 2), 28% +/- 11% (stage III), and 7% +/- 4% (stage 4). Although no patient had a diagnosis of polyposis syndrome before diagnosis of CRC, 17 (22%) had colon polyps and eight (including two who previously underwent pelvic radiotherapy) had multiple polyps. CONCLUSION Initial signs and symptoms of CRC are similar in pediatric and adult patients. The strikingly higher frequency of mucinous histology suggests that the biology of CRC differs in pediatric and adult patients and may contribute to poor outcomes. Children should be included in prospective clinical trials for CRC.

Clinical Features and Outcome of Initially Unresected Nonmetastatic Pediatric Nonrhabdomyosarcoma Soft Tissue Sarcoma

PURPOSE To describe the clinical features, response to therapy, and outcome of pediatric patients with initially unresected nonmetastatic nonrhabdomyosarcoma soft tissue sarcoma (NRSTS). PATIENTS AND METHODS We retrospectively reviewed the presenting clinical features and tumor characteristics of all 40 pediatric patients with initially unresected nonmetastatic NRSTS who were seen at our institution between March 1962 and December 1996. A subset of 27 patients for whom complete treatment information was available was analyzed to determine whether response to therapy was associated with local disease control and event-free and overall survival. RESULTS More than 70% of the 40 patients had tumors with high-risk features (tumor size > 5 cm, high grade, invasiveness). For the 27 patients included in the outcome analysis, 5-year event-free survival and survival estimates were 33% +/- 9% and 56% +/- 10%, respectively. Ten (37%) of these patients had a complete or partial response to neoadjuvant chemotherapy and/or radiotherapy, and only two of the 10 had residual tumor after surgery. Combined chemotherapy and radiotherapy seemed more effective than either modality alone in inducing a response, but the response to neoadjuvant therapy did not predict outcome. Most treatment failures were local, and postrelapse survival was poor (19% +/- 10%). CONCLUSION Initially unresected NRSTS constitutes a unique subgroup of pediatric sarcomas that commonly present with high-risk features and respond poorly to neoadjuvant therapy. Only about one third of patients treated with multimodal therapy remain disease-free, and local control is the major limiting factor in achieving cure. More effective risk-directed treatments are needed for this unique subgroup of patients.