Laura S. Finn

IgA Plasma Cell Infiltration of Proximal Respiratory Tract, Pancreas, Kidney, and Coronary Artery in Acute Kawasaki Disease

The etiology and pathogenesis of Kawasaki disease (KD) remain unknown. As previously reported, in US patients with acute KD, IgA plasma cells (PCs) infiltrate the vascular wall. To determine whether IgA PCs are increased at mucosal sites in KD and to determine whether other nonvascular KD tissues are infiltrated by IgA PCs, the cells were immunolocalized and quantitated in tissue sections taken from 18 US and Japanese patients who died of acute KD and from 10 age-matched controls. IgA PCs were significantly increased in the trachea of patients who died of acute KD, compared with controls (P<.01), a finding that was similar to findings in children with fatal respiratory viral infection. IgA PCs also infiltrated coronary artery, pancreas, and kidney in all KD patients. These findings strongly support entry of the KD etiologic agent through the upper respiratory tract, resulting in an IgA immune response, with systemic spread to vascular tissue, pancreas, and kidney.

Polyomavirus Nephropathy in Pediatric Kidney Transplant Recipients

Given the limited information regarding BK virus‐associated nephropathy (BKVN) in pediatric kidney transplant recipients, we assessed the incidence, risk factors, clinical and virologic features of BKVN in pediatric renal transplant recipients at a single transplant center by means of a retrospective cohort study. Histologically confirmed BKVN developed in 6 of 173 (3.5%) kidney transplant recipients at a median of 15 months post‐transplant (range: 4–47 months). At a median follow‐up of 28 months (range: 5–32), all patients had functioning grafts with mean creatinine and GFR of 1.9 mg/dL and 58 mL/min/1.73 m2, respectively. At the time of diagnosis, all cases had viruria (median 6.1 × 106 copies/mL, range: 105 to 3.9 × 108 copies/mL) and viremia (median 21 000 copies/mL, range: 10 000–40 000 copies/mL). Recipient seronegativity for BKV was significantly associated with the development of BKVN (p = 0.01). BKVN is an important cause of late allograft dysfunction and is strongly associated with recipient seronegativity in pediatric kidney transplant recipients. Further studies to confirm this finding and to define the clinical utility of routine pre‐transplant BKV serologic testing are warranted.

Calretinin Immunohistochemistry versus Acetylcholinesterase Histochemistry in the Evaluation of Suction Rectal Biopsies for Hirschsprung Disease

Diagnosis of Hirschsprung disease (HSCR) relies on histologic and/or histochemical staining of sections from suction rectal biopsies. Acetylcholinesterase histochemistry (AChE) facilitates diagnosis but is not universally employed, in part because it requires special tissue handling. Calretinin immunohistochemistry (IHC) may be a useful alternative, because loss of calretinin immunoreactive nerves reportedly correlates spatially with aganglionosis. We investigated the patterns of calretinin IHC in suction rectal biopsies from HSCR and non-HSCR patients and compared the diagnostic value of calretinin IHC with a widely used rapid AChE method. In suction rectal biopsies that contain ganglion cells, small nerves in the lamina propria, muscularis mucosae, and superficial submucosa contain granular aggregates of calretinin immunoreactivity. Immunolabeling of these nerves is completely absent in the aganglionic biopsies of HSCR patients. Multiple observers independently reviewed calretinin IHC and AChE sections of suction rectal biopsies from 14 HSCR patients and 17 non-HSCR controls. Five observers, blinded to the correct diagnosis, scored each patients calretinin IHC and AChE slides as HSCR, not HSCR, or equivocal. The frequencies of major and minor discrepant diagnoses were compared. Calretinin IHC yielded no misdiagnoses or major discrepancies between observers. In contrast, 2 misdiagnoses and significantly more interobserver disagreement resulted from the AChE-stained sections. Calretinin IHC appears to be a reasonable, and potentially superior, alternative to AChE as an adjunctive diagnostic method for evaluating suction rectal biopsies for HSCR.

Apurinic/apyrimidinic endonuclease activity is associated with response to radiation and chemotherapy in medulloblastoma and primitive neuroectodermal tumors

Purpose: Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair activity that confers resistance to radiation- and alkylator-induced cytotoxic abasic sites in human cells. We assayed apurinic/apyrimidinic endonuclease activity in medulloblastomas and primitive neuroectodermal tumors (PNET) to establish correlates with tumor and patient characteristics and with response to adjuvant radiation plus multiagent chemotherapy. Experimental Design: Ap endo activity was assayed in 52 medulloblastomas and 10 PNETs from patients 0.4 to 21 years old. Ape1/Ref-1, the predominant human Ap endo activity, was measured in 42 medulloblastomas by immunostaining. Cox proportional hazards regression models were used to analyze the association of activity with time to tumor progression (TTP). Results: Tumor Ap endo activity varied 180-fold and was significantly associated with age and gender. Tumor Ape1/Ref-1 was detected almost exclusively in nuclei. In a multivariate model, with Ap endo activity entered as a continuous variable, the hazard ratio for progression after adjuvant treatment in 46 medulloblastomas and four PNETs increased by a factor of 1.073 for every 0.01 unit increase in activity (P ≤ 0.001) and was independent of age and gender. Suppressing Ap endo activity in a human medulloblastoma cell line significantly increased sensitivity to 1,3-bis(2-chlororethyl)-1-nitrosourea and temozolomide, suggesting that the association of tumor activity with TTP reflected, at least in part, abasic site repair. Conclusions: Our data (a) suggest that Ap endo activity promotes resistance to radiation plus chemotherapy in medulloblastomas/PNETs, (b) provide a potential marker of treatment outcome, and (c) suggest clinical use of Ap endo inhibitors to overcome resistance.

Subclinical Viremia Increases Risk for Chronic Allograft Injury in Pediatric Renal Transplantation

The impact of subclinical viral infection on chronic allograft injury in the pediatric renal transplant population is not well defined. We prospectively assessed cytomegalovirus (CMV) and Epstein-Barr virus (EBV) DNAemia by monthly PCR in 55 pediatric renal transplant recipients for the first 2 years after transplantation. Subclinical CMV and EBV infection occurred in 22 and 36%, respectively. Multivariable linear regression analysis suggested that both subclinical CMV and EBV infection independently associate with significant declines in GFR during the first 2 years after transplantation. CMV seronegativity associated with a significantly greater decline in GFR than seropositivity (P < 0.01). Subclinical CMV infection and subclinical EBV infection each associated with approximately fourfold greater odds of histologic evidence of chronic allograft injury (odds ratio 4.61 [95% confidence interval 1.18 to 18.07] and odds ratio 4.33 [95% confidence interval 1.34 to 14.00], respectively). An increase in viral load of CMV or EBV also associated with increased risk for moderate to severe chronic allograft injury. Taken together, these results demonstrate an association between subclinical CMV and EBV infections, which occur despite standard antiviral prophylaxis, and chronic allograft injury in pediatric renal transplant recipients.

Novel FOXF1 Mutations in Sporadic and Familial Cases of Alveolar Capillary Dysplasia with Misaligned Pulmonary Veins Imply a Role for its DNA Binding Domain

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare and lethal developmental disorder of the lung defined by a constellation of characteristic histopathological features. Nonpulmonary anomalies involving organs of gastrointestinal, cardiovascular, and genitourinary systems have been identified in approximately 80% of patients with ACD/MPV. We have collected DNA and pathological samples from more than 90 infants with ACD/MPV and their family members. Since the publication of our initial report of four point mutations and 10 deletions, we have identified an additional 38 novel nonsynonymous mutations of FOXF1 (nine nonsense, seven frameshift, one inframe deletion, 20 missense, and one no stop). This report represents an up to date list of all known FOXF1 mutations to the best of our knowledge. Majority of the cases are sporadic. We report four familial cases of which three show maternal inheritance, consistent with paternal imprinting of the gene. Twenty five mutations (60%) are located within the putative DNA‐binding domain, indicating its plausible role in FOXF1 function. Five mutations map to the second exon. We identified two additional genic and eight genomic deletions upstream to FOXF1. These results corroborate and extend our previous observations and further establish involvement of FOXF1 in ACD/MPV and lung organogenesis.

Diffuse abnormal layering of small intestinal smooth muscle is present in patients with FLNA mutations and x-linked intestinal pseudo-obstruction.

X-linked intestinal pseudo-obstruction, a rare disorder caused by mutations in FLNA, the gene encoding the cytoskeletal protein filamin A, has been regarded as a hereditary enteric neuropathy largely on the basis of sparse and incomplete pathologic studies. Diffuse abnormal layering of small intestinal smooth muscle (DAL) is a rare malformation, which has only been described in 4 patients (all male, 3 in the same family) with intestinal pseudo-obstruction. We report DAL in 5 male patients (2 families) with intestinal pseudo-obstruction and mutations in FLNA. Light microscopic, ultrastructural, and immunohistochemical studies showed abnormal lamination of the small intestinal muscularis propria with associated absent or severely reduced FLNA immunoreactivity. Intestinal samples from the oldest patient in the series, a teenager, showed multinucleate myocytes in small and large intestine, along the submucosal surface of the muscularis propria. As neither DAL nor the pattern of myocyte multinucleation observed in our patients have been described outside the context of X-linked intestinal pseudo-obstruction, these histopathologic features may be specific for this hereditary disorder and suggest an underlying myopathic basis for dysmotility in affected patients.

Liver histology and alanine aminotransferase levels in children and adults with chronic hepatitis C infection

Background: Chronic hepatitis C is often a mild disease in children, but whether this is related to younger age or shorter duration of infection is unclear. Histologic severity has been shown to correlate with duration of infection regardless of age. Objectives: We compared histologic findings in children and adults with chronic hepatitis C while controlling for sex, duration of infection, hepatitis C virus (HCV)-RNA level, and genotype. Methods: Twenty-one children and 52 adults whose infection was less than 20 years in duration and who had undergone a liver biopsy were included. Two blinded liver pathologists reviewed the liver biopsies and scored inflammatory activity and fibrosis using the modified Knodell scoring system. Results: The groups were the same with respect to HCV-RNA level (P = 0.8), and genotype (P = 0.6) but differed in duration of disease (P = 0.01) and sex composition (P = 0.005). Covariate analysis showed no influence of genotype, duration of infection, or HCV-RNA level on outcome. In controlling for sex, children had significantly milder liver disease and alanine aminotransferase (ALT) elevations. Conclusions: With equal duration of infection, HCV-RNA level, and genotype, children have lower serum ALT levels and less severe liver disease than adults infected with HCV.

Desmoplastic Nested Spindle Cell Tumor of Liver: Report of Four Cases of a Proposed New Entity

Abstract:We describe a distinctive tumor of the liver in four children composed of nested spindled and epithelioid cells with extensive desmoplasia that we have termed “desmoplastic nested spindle cell tumor of the liver.” All four patients were previously healthy. One patient had a presumptive diagnosis of hepatic hemangioma 11 years prior to presentation. Grossly, the tumors were well circumscribed, lobular white masses, ranging from 2.8 to 15 cm in diameter. These tumors were characterized by the presence of cohesive nests of plump, bland spindle cells arranged in short fascicles with an accompanying desmoplastic stroma. Epithelioid areas ranging from palisading epithelioid cells at the periphery of some nests to pseudoglandular and polygonal cells with intercellular bridges were invariably present. Mitotic activity was low. Calcification and ossification were present. Non-neoplastic bile ducts and hepatic elements were seen both within and surrounding the tumor cell nests. Each tumor displayed cytoplasmic reactivity for vimentin, pan-cytokeratin, CD57, and nuclear staining for WT1. Neuroendocrine markers were negative. Ultrastructurally, the tumor cells showed focally well-developed cell junctions, basal lamina, and few cytoplasmic organelles. All tumors were confined to the liver and were resected without complication. Two patients received postoperative adjuvant therapy for presumed hepatoblastoma. The patients are doing well without recurrence at 7.5 years, 7 years, 5 years, and 8 months post-surgery. The morphologic appearance and immunohistochemical profile of these lesions are unique in our experience and represent a new category of pediatric liver tumor.

BK nephropathy in pediatric hematopoietic stem cell transplant recipients.

Abstract:  BK nephropathy is a known cause of renal insufficiency in kidney transplant recipients. Activation of the polyoma virus may also occur in the native kidneys of non‐renal allograft recipients. BK nephropathy has only been reported in a few patients after HCT, most being adult patients, and the single reported pediatric case had evidence of hemorrhagic cystitis. The response to antiviral therapy also seems to differ widely. Here, we describe two cases of BK nephropathy in the native kidneys of HCT recipients exposed to high levels of immunosuppression because of GVHD. Neither of our patients had any evidence of hemorrhagic cystitis. We present definitive renal pathology and detailed chronological evidence of the rising serum creatinine with simultaneous serum and urine BK PCR titers. In one of our cases, antiviral therapy did not seem beneficial as documented by continued renal dysfunction and elevated serum/urine BK PCR titers. Based on our report, intense immunosuppression in pediatric HCT recipients seems to be involved in the activation of BK virus and BK nephropathy should be suspected even in the absence of hematuria in HCT recipients with unexplained renal dysfunction.