Kathleen Patterson

Chimeric cells of maternal origin in juvenile idiopathic inflammatory myopathies

We identified maternal microchimerism by fluorescence in-situ hybridisation in magnetically-separated CD4 or CD8 peripheral blood cells of eight of nine male patients with juvenile idiopathic inflammatory myopathy, compared with two of nine healthy male controls. We also found maternal microchimerism in inflammatory lesions (one skin sample and nine muscle biopsy samples) of all ten patients examined, compared with two of ten biopsy samples from patients with other muscle disorders. These results suggest that maternal cells may be involved in the pathogenesis of juvenile idiopathic inflammatory myopathy.

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.

The immunohistological diagnosis of E. coli O157: H7 colitis: Possible association with colonic ischemia

Objective:E. coli O157:H7 may cause hemorrhagic colitis resembling ischemic colitis. Diagnosis is usually made by finding sorbitol-negative colonies on MacConkey agar that react with O157 and H7 antisera. Most ischemic colitis is idiopathic, but some may be caused by E. coli O157:H7, inasmuch as this organism can produce fibrin thrombi in colon vasculature. The objectives of this study were to determine whether E. coli O157:H7 infection can be diagnosed retrospectively from paraffin blocks of colon sections and whether an association exists between E. coli O157:H7 infection and colonic ischemia.Methods:Paraffin-embedded sections of normal colon (n = 2) and various colitides [ischemic (n = 11), E. coli O157:H7 (n = 2), IBD (n = 8) and pseudomembranous (n = 3)] were used. Sections were deparaffinized, rehydrated, incubated with 3% peroxide in methanol, rinsed, and incubated with peroxidase-labeled antibody isolated from goats immunized with whole E. coli O157:H7. Sections were stained with peroxidase chromagen reagent and counterstained with hematoxylin. Coarse, granular, orange-brown staining was considered positive. To determine the localization of the chromagen deposits, three cases that stained positive, including one of the culture-proved E. coli O157:H7 colitis and two of colonic ischemia, were processed for electron microscopy.Results:Both cases (100%) of E. coli O157:H7 colitis and three of 11 (27.3%) cases of ischemic colitis stained positive by light microscopy. In one culture-proved case, electron microscopy demonstrated staining of bacillary structures; in two cases of colonic ischemia, extensive deposits of chromagen material were present that were associated neither with inflammatory cells nor with bacterial forms.Conclusions:Immunoperoxidase staining of archival sections may be used to diagnose E. coli O157:H7 infection. An etiological role for this organism is possible in some cases of colonic ischemia.

Successful dose-intensive treatment of desmoplastic small round cell tumor in three children

Desmoplastic small round cell tumor (DSRCT) is a rare soft tissue tumor of primitive origin occurring primarily in children and young adults. Based on published reports in the literature, the response to conventional chemotherapy is poor. We report three pediatric patients successfully treated with dose-intensive, multimodal therapy. Between August 1994 and March 1998, we evaluated three consecutive patients with DSRCT at Childrens Hospital and Regional Medical Center, Seattle, Washington. We established the diagnosis based on clinical presentation, radiologic staging, and pathologic review with immunohistochemical staining. All patients received a combined modality protocol including dose-intensive chemotherapy (two of them with peripheral blood stem cell [PBSC] support), second look surgery, and consolidative local irradiation. The patients remain in continuous remission at 66, 42, and 26 months after diagnosis, respectively. Two of our patients were younger than any previously reported patient, extending the age group for which DSRCT should be considered on diagnosis of small round cell tumors. The uniform survival achieved in our series indicates potential benefit for the combination of dose-intensive multiagent chemotherapy, local irradiation, and aggressive surgical approach in this disease.

Mesenchymal hamartoma of the liver

Mesenchymal hamartoma of the liver is the second most common benign liver tumor of childhood. Ultrasonography demonstrates a cystic lesion that may be very large. Computed tomographic scan will further establish the location and its relationship to vascular anatomy. Most will be amenable to gross total resection with clear margins. To illustrate the radiological and gross operative features, we present a 9-month-old male infant with a mesenchymal hamartoma with classic features.

Mitochondrial Muscle Pathology

The diagnosis of mitochondrial disease is challenging and requires a multidisciplinary approach for investigation. Despite the complexity, a specific diagnosis can be achieved in many cases. A specific diagnosis may provide prognostic information for the patient and the option of prenatal testing for the family in a subsequent pregnancy. the case reports in this section nicely illustrate several common pediatric clinical presentations of mitochondrial disease and a systematic approach to investigation.

Ovarian Sarcoma with Pathologic Features of Clear Cell Sarcoma of the Kidney

We report a case of an unusual sarcoma arising in the ovary of an infant girl. Histologically, the tumor was composed of clear, undifferentiated cells set in an arborizing vascular stroma. Immunohistochemical staining was positive only for vimentin. Ultrastructural evaluation demonstrated undifferentiated cells with interdigitating broad cell processes that encompassed irregular electron lucent spaces that contained flocculent extracellular material. Light and electron microscopic features of the tumor resembled a clear cell sarcoma of the kidney. Although the cell of origin is unproven, both tumors may arise from primitive mesenchymal cells that may not be restricted to the kidney.

Evaluation of early marrow response in childhood aneuploid acute lymphoblastic leukemia: flow cytometric DNA analysis versus standard morphology.

Despite improved survival rates for childhood acute lymphoblastic leukemia (ALL), the relapse rate remains at 20–30%. Early peripheral blood and bone marrow (BM) responses have been associated with more favorable outcomes; all current children’s cancer group (CCG) protocols for ALL require BM evaluation at days 7 and 14 with subsequent therapy based on the results. Morphologic interpretation of aspirate smears during induction chemotherapy is challenging, as the samples are often hypocellular, excessively friable, and cytologically altered by drugs. We have shown discordancy of day 7 and 14 BM lymphoblast counts using morphologic and flow cytometric immunophenotypic analyses (FC). The aim of our study was to determine the utility, reliability, and cost effectiveness of lymphoblast enumeration using DNA content analysis by flow cytometry (DNA-FC) and to further demonstrate the subjectivity of morphologic review. All new cases of ALL had DNA-FC and FC analyses. The percentage of lymphoblasts as determined by both methods was compared for 82 aneuploid cases. Three pathologists independently reviewed aspirate smears from 39 bone marrow samples of aneuploid ALL that were obtained during early induction. These results were compared among themselves and with the results obtained by DNA-FC. We found excellent correlation between the percentage of lymphoblasts as determined by DNA-FC and FC (R2 = 0.97) over a range of 0 to 99%. Pathologic review agreed with the DNA-FC, on average, 68%. The sensitivity, specificity, and positive and negative predictive values of morphologic review, averaged 53, 84, 78, and 63%, respectively, when using DNA-FC as the “gold standard.” All three pathologists achieved agreement of lymphoblast percentage by morphology in 72%. In our laboratory, the use of DNA-FC equates to one-sixth the time and one-half the price of FC per exam. We have shown a strong correlation between blast counts determined by DNA-FC and FC. DNA-FC is an objective, economical, and reliable method to assess early response in induction marrows from aneuploid ALL where morphology is often uninterpretable. This test is highly reproducible and available at most pediatric institutions. Prospective studies need to be employed to evaluate the effect of more definitive methods (DNA-FC and FC) of assessing the early response in bone marrows on prognosis.