Diagnostic application of cyclin D1 fluorescent in situ hybridization for histologically undetermined early lesions of acral melanoma in situ: A case series.

Histologically undetermined early acral melanoma in situ (HUAMIS) is rare but a diagnostic challenge, being clinically and dermoscopically MIS (late onset, a large size (>7 mm), parallel ridges pattern) but microscopically without recognizable cytological atypia. Cyclin D1 (CCND1) gene amplification is a genetic aberration occurring in the early radial growth phase of AMs and could thus help determine malignancy for this disease. We determine the value of CCND1 amplification by FISH as a diagnostic marker for HUAMIS. CCND1 amplification was examined in paraffin-embedded skin biopsies and excisions using a dual-probes fluorescence in situ hybridization (FISH) (11q13 and CEP11). One FISH-negative case 6 was additionally examined by Mypath Melanoma (qRT-PCR). Seventeen cases (12 dysplastic nevi, 3 AMIS, and 2 invasive AM) were served as negative controls for FISH. All six patients (4 females and 2 males) were Hispanic. Pigment lesions were on the left plantar foot (4), right third finger palm (1), and right thumb subungual (1). All cases showed similar clinical and dermoscopical characteristics, including late onset (50 to 74 years old), long duration (from 2 to 15 years), large-sized pigments (from 16 to 40 mm), and a parallel ridge pattern. Junctional melanocytes with no or minimal atypia from five cases showed CCND1 amplifications. Four of 5 cases were received 1st or/and 2nd wide excisions, which demonstrated foci of histologically overt MIS. One FISH-negative case 6 demonstrated "likely malignancy" scores (>2) by Mypath Melanoma (qRT-PCR). None of negative controls showed the amplification. We propose here a simple CCND1 FISH is a practical diagnostic test to determine the malignancy of the very early progression phase of AM preceding histopathologically defined MIS. Cases presented here could be an indolent subtype of AMIS characterized by carrying a long latent radial growth phase without vertical growth, mimicking lentigo maligna.

A How-to Guide to Building a Robust SARS-CoV-2 Testing Program at a University-Based Health System.

When South Florida became a hot spot for COVID-19 disease in March 2020, we faced an urgent need to develop test capability to detect SARS-CoV-2 infection. We assembled a transdisciplinary team of knowledgeable and dedicated physicians, scientists, technologists, and administrators who rapidly built a multiplatform, polymerase chain reaction- and serology-based detection program, established drive-through facilities, and drafted and implemented guidelines that enabled efficient testing of our patients and employees. This process was extremely complex, due to the limited availability of needed reagents, but outreach to our research scientists and multiple diagnostic laboratory companies, and government officials enabled us to implement both Food and Drug Administration authorized and laboratory-developed testing-based testing protocols. We analyzed our workforce needs and created teams of appropriately skilled and certified workers to safely process patient samples and conduct SARS-CoV-2 testing and contact tracing. We initiated smart test ordering, interfaced all testing platforms with our electronic medical record, and went from zero testing capacity to testing hundreds of health care workers and patients daily, within 3 weeks. We believe our experience can inform the efforts of others when faced with a crisis situation.

Comparison Between Integrated Genomic DNA/RNA Profiling and Fluorescence In Situ Hybridization in the Detection of MYC, BCL-2, and BCL-6 Gene Rearrangements in Large B-Cell Lymphomas.

OBJECTIVES: To compare fluorescence in situ hybridization (FISH) and a commercially available sequencing assay for comprehensive genomic profiling (CGP) to determine the best approach to identify gene rearrangements (GRs) in large B-cell lymphomas (LBCLs). METHODS: Comparison of standard-of-care FISH assays (including a two-probe approach for MYC; break-apart and fusion probes) and an integrated genomic DNA/RNA sequencing CGP approach on a set of 69 consecutive LBCL cases. RESULTS: CGP detected GRs, including those involving MYC (1), BCL-2 (3), and BCL-6 (3), not detected by FISH. FISH detected non-IgH-MYC (4) and BCL-6 (2) GRs that were not detected by CGP. In four instances, standalone CGP or FISH testing would have missed a double-hit lymphoma. CONCLUSIONS: CGP was superior to FISH in the detection of IgH-MYC rearrangements but was inferior for the detection of non-IgH-MYC rearrangements. Our study demonstrates the rationale for development of a customized approach to identify GRs in LBCLs.

Unusual Variants of Follicular Lymphoma: Case-based Review.

Follicular lymphoma (FL) is one of the most frequently diagnosed lymphomas in the United States and Europe. The definition of and basic approach to diagnosis and grading of FL is essentially unchanged in the recently updated revision of the World Health Organization (WHO) classification. FL is a biologically and histopathologically heterogeneous disease. Although there is an improved understanding of some FL variants and specific subtypes, there are cases whose recognition is particularly challenging, either because they have unusual features or represent examples of new or rare variants. Herein, we share a series of unusual and difficult to recognize FLs with the goal of increasing awareness of the expanding histopathologic variability in FL. Unusual FL discussed here include: FL with Castleman-like changes, FL with plasmacytic differentiation, and immunoglobulin G4-positive plasma cells in the setting of immunoglobulin G4-related disease, FL with marginal zone differentiation and involving mucosa-associated lymphoid tissue sites, diffuse FL variant expressing CD23 with STAT6 mutation, large B-cell lymphoma with IRF4 rearrangement, CD10-negative and MUM1-positive aggressive FL, and Epstein-Barr virus-positive FL.

Monosomy chromosome 21 compensated by 21q22.11q22.3 duplication in a case with small size and minor anomalies.

BACKGROUND: Partial monosomy 21 is a rare finding with variable sizes and deletion breakpoints, presenting with a broad spectrum of phenotypes. CASE PRESENTATION: We report a 10-month-old boy with short stature, minor anomalies and mild motor delay. The patient had a monosomy 21 and duplication of the 21q22.11q22.3 region on the remaining derivative chromosome 21 which represents a partial 21q uniparental disomy of paternal origin, upd(21q22.11q22.3)pat. The abnormalities were characterized by karyotyping, FISH, chromosomal microarray, and genotyping. CONCLUSIONS: This is the first case showing a monosomy 21 compensated by upd(21q22.11q22.3) as a mechanism of genomic rescue. Because there is no strong evidence showing imprinting on chromosome 21, the uniparental disomy itself is not associated with abnormal phenotype but has reduced phenotype severity of monosomy 21. We reviewed the previously published cases with isolated 21q deletions and identified a common deletion of 5.7 Mb associated with low birth weight, length and head circumference in the 21q21.2 region.

Copy number variant discrepancy resolution using the ClinGen dosage sensitivity map results in updated clinical interpretations in ClinVar.

Conflict resolution in genomic variant interpretation is a critical step toward improving patient care. Evaluating interpretation discrepancies in copy number variants (CNVs) typically involves assessing overlapping genomic content with focus on genes/regions that may be subject to dosage sensitivity (haploinsufficiency (HI) and/or triplosensitivity (TS)). CNVs containing dosage sensitive genes/regions are generally interpreted as "likely pathogenic" (LP) or "pathogenic" (P), and CNVs involving the same known dosage sensitive gene(s) should receive the same clinical interpretation. We compared the Clinical Genome Resource (ClinGen) Dosage Map, a publicly available resource documenting known HI and TS genes/regions, against germline, clinical CNV interpretations within the ClinVar database. We identified 251 CNVs overlapping known dosage sensitive genes/regions but not classified as LP or P; these were sent back to their original submitting laboratories for re-evaluation. Of 246 CNVs re-evaluated, an updated clinical classification was warranted in 157 cases (63.8%); no change was made to the current classification in 79 cases (32.1%); and 10 cases (4.1%) resulted in other types of updates to ClinVar records. This effort will add curated interpretation data into the public domain and allow laboratories to focus attention on more complex discrepancies.

Myeloid neoplasms with features intermediate between primary myelofibrosis and chronic myelomonocytic leukemia.

Monocytosis can develop during disease course in primary myelofibrosis simulating that seen in chronic myelomonocytic leukemia, and should not lead to disease reclassification. In contrast, at presentation, rare cases have clinical, morphologic, and molecular genetic features truly intermediate between primary myelofibrosis and chronic myelomonocytic leukemia. The taxonomy and natural history of these diseases are unclear. We identified cases which either: (1) fulfilled the 2008 World Health Organization criteria for primary myelofibrosis but had absolute monocytosis and, when available, chronic myelomonocytic leukemia-related mutations (ASXL1, SRSF2, TET2) or (2) fulfilled criteria of chronic myelomonocytic leukemia but had megakaryocytic proliferation and atypia, marrow fibrosis, and myeloproliferative-type driver mutations (JAK2, MPL, CALR). Patients with established primary myelofibrosis who developed monocytosis and those with chronic myelomonocytic leukemia with marrow fibrosis were excluded. By combining the pathology databases of two large institutions, six eligible cases were identified. Patients were predominantly male and elderly with monocytosis at diagnosis (average 17.5%/2.3 × 103/µl), organomegaly, primary myelofibrosis-like atypical megakaryocytes admixed with a variable number of chronic myelomonocytic leukemia-like hypolobated forms, variable myelodysplasia, marrow fibrosis and osteosclerosis. All had a normal karyotype and no myelodysplasia-associated cytogenetic abnormalities. Five of the patients in whom a more extensive molecular characterization was performed showed co-mutations involving JAK2 or MPL and ASXL1, SRSF2, TET2, NRAS, and/or KRAS. Disease progression has occurred in all and two have died. Rare patients present with features that overlap between primary myelofibrosis and chronic myelomonocytic leukemia and are thus difficult to classify based on current World Health Organization criteria. Biologically, these cases likely represent primary myelofibrosis with monocytosis, dysplasia, and secondary (non-driver) mutations at presentation. Alternatively, they may represent a true gray zone of neoplasms. Their clinical behavior appears aggressive and innovative therapeutic approaches may be beneficial in this particular subset.

A Case of AML Characterized by a Novel t(4;15)(q31;q22) Translocation That Confers a Growth-Stimulatory Response to Retinoid-Based Therapy.

Here we report the case of a 30-year-old woman with relapsed acute myeloid leukemia (AML) who was treated with all-trans retinoic acid (ATRA) as part of investigational therapy (NCT02273102). The patient died from rapid disease progression following eight days of continuous treatment with ATRA. Karyotype analysis and RNA-Seq revealed the presence of a novel t(4;15)(q31;q22) reciprocal translocation involving the TMEM154 and RASGRF1 genes. Analysis of primary cells from the patient revealed the expression of TMEM154-RASGRF1 mRNA and the resulting fusion protein, but no expression of the reciprocal RASGRF1-TMEM154 fusion. Consistent with the response of the patient to ATRA therapy, we observed a rapid proliferation of t(4;15) primary cells following ATRA treatment ex vivo. Preliminary characterization of the retinoid response of t(4;15) AML revealed that in stark contrast to non-t(4;15) AML, these cells proliferate in response to specific agonists of RARα and RARγ. Furthermore, we observed an increase in the levels of nuclear RARγ upon ATRA treatment. In summary, the identification of the novel t(4;15)(q31;q22) reciprocal translocation opens new avenues in the study of retinoid resistance and provides potential for a new biomarker for therapy of AML.

Screening of deafness-causing DNA variants that are common in patients of European ancestry using a microarray-based approach.

The unparalleled heterogeneity in genetic causes of hearing loss along with remarkable differences in prevalence of causative variants among ethnic groups makes single gene tests technically inefficient. Although hundreds of genes have been reported to be associated with nonsyndromic hearing loss (NSHL), GJB2, GJB6, SLC26A4, and mitochondrial (mt) MT-RNR1 and MTTS are the major contributors. In order to provide a faster, more comprehensive and cost effective assay, we constructed a DNA fluidic array, CapitalBioMiamiOtoArray, for the detection of sequence variants in five genes that are common in most populations of European descent. They consist of c.35delG, p.W44C, p.L90P, c.167delT (GJB2); 309kb deletion (GJB6); p.L236P, p.T416P (SLC26A4); and m.1555A>G, m.7444G>A (mtDNA). We have validated our hearing loss array by analyzing a total of 160 DNAs samples. Our results show 100% concordance between the fluidic array biochip-based approach and the established Sanger sequencing method, thus proving its robustness and reliability at a relatively low cost.

Primary Mediastinal Large B-Cell Lymphoma With Translocations Involving BCL6 and MYC (Double-Hit Lymphoma).

OBJECTIVES: Primary mediastinal large B-cell lymphomas (PMLBCLs) are aggressive lymphomas with characteristic clinical, morphologic, and immunophenotypic features. "Double-hit" (DH) lymphomas are B-cell neoplasms characterized by a translocation involving MYC and either BCL2 or BCL6 In the indexed literature, there are no reported cases of PMLBCL associated with DH or triple-hit events. METHODS: Herein, we present a case of a 15-year-old girl with PMLBCL who had typical clinical, morphologic, and immunophenotypic features. RESULTS: Fluorescent in situ hybridization studies showed rearrangements involving MYC and BCL6 We also excluded the possibility of a reciprocal t(3;8) (3q27;8q24) BCL6/MYC translocation. CONCLUSIONS: This case expands the current spectrum of lymphomas subtypes in which DH can be found and supports the rationale for cytogenetic testing for DH abnormalities in all cases of aggressive large B-cell lymphomas regardless of subtype.

HER2 FISH classification of equivocal HER2 IHC breast cancers with use of the 2013 ASCO/CAP practice guideline.

The status of human epidermal growth factor receptor 2 (HER2, ERBB2) determines the eligibility of breast cancer patients to receive HER2-targeted therapy. The majority of HER2 testing in the U.S. is performed using a combination of immunohistochemistry (IHC) screening followed by fluorescence in situ hybridization (FISH) for IHC equivocal cases. In 2013, the American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) updated the guideline for HER2 testing. This study evaluates the impact of the 2013 ASCO/CAP updated guideline on final HER2 FISH classification of breast cancers with an equivocal IHC result. For each case, we reported a FISH result according to the 2013 updated guideline and recorded a separated result using the 2007 guideline for investigational purpose. McNemar's test and Bowker's symmetry test were used to compare the classifications by the two guidelines. Among 172 HER2 IHC 2+ equivocal cases, use of the 2103 guideline changed classifications in 36 cases (21 %) when compared with the results expected by use of the 2007 guideline, and yielded a higher proportion of positive (28.5 vs. 23.3 %) and equivocal (16.3 vs. 4.1 %), and a lower proportion of negative (55.2 vs. 72.7 %) cases (p < 0.001). The major classification change with use of the updated guideline is from the HER2 FISH negative to equivocal in 26 cases (15 %). Our study has shown that implementation of the 2013 ASCO/CAP updated guideline has significant impact on HER2 classification for breast cancers with an equivocal HER2 IHC result and therefore increased the use of HER2-targeted therapy. Our data have also shown that reflex FISH is effective for final classification of the IHC equivocal cases and that polysomy 17 (CEP17 copy number ≥3/cell) is present in a significantly higher proportion of cases with an equivocal HER2 FISH classification.

De novo acute myeloid leukemia with monocytoid blasts and erythrophagocytosis.

KEY CLINICAL MESSAGE: Acute myeloid leukemia (AML) with t(8:16) is an infrequent acute leukemia subtype. It can occur de novo or more frequently therapy-related. The presence of blasts with monocytoid morphology and erythrophagocytosis suggest the presence of the t(8;16).

Endoscopic ultrasound guided fine needle aspiration with fluorescence in situ hybridization analysis in 104 patients with pancreatic mass.

BACKGROUND AND AIM: Diagnosis of pancreatic malignancy is often based on cytological specimens collected by endoscopic ultrasound guided fine needle aspiration (EUS FNA). Several factors can decrease sensitivity of EUS FNA for pancreatic cancer: well-differentiated tumors, pancreatitis, blood, necrosis and slides with low cellularity. The objective of this study is to report on the use of fluorescence in situ hybridization (FISH) analysis combined with cytology in pancreatic masses. METHODS: EUS database and medical records of patients referred for EUS between January 2009 through august 2013 were reviewed. Data on cytology, FISH and surgical pathology were reviewed. Surgical pathology, death or extended clinical follow-up were used to verify correct diagnosis of malignancy. FISH performed using a four-set DNA probe for chromosomes 3, 7, 17, and band 9p21 in patients with inconclusive immediate cytology reading. Sensitivity of cytology and FISH were compared. RESULTS: Study cohort comprised of 104 patients with FISH analysis on EUS FNA specimens of pancreatic masses (74 adenocarcinoma, 7 neuroendocrine tumor and 23 benign. Sensitivity of cytology and FISH for carcinoma was respectively: 62% and 81%. Sensitivity of FISH + cytology was 89%. The specificity of FISH and cytology was 100%. The most common abnormality on FISH was a 9p21 deletion seen in 43 patients (58%) followed by polysomy of 7 (46%). FISH detected malignancy in 23 patients with negative cytology. CONCLUSIONS: In patients with inconclusive immediate cytology reading, FISH is superior to cytology and improves overall sensitivity. The 9p21 deletion is the most common abnormality seen in this cohort of patients with pancreatic cancer.

Searching for mammary analogue [corrected] secretory carcinoma of salivary gland among its mimics.

Mammary analog secretory carcinoma of salivary gland is a recently described entity with unique morphologic, clinical, and genetic characteristics, including the characteristic t(12;15)(p13;q25) with ETV6-NTRK3 translocation found in secretory carcinomas of the breast. Before their initial description, these salivary gland tumors were generally diagnosed as acinic cell carcinoma or adenocarcinoma. For the purpose of this study, all cases of salivary gland acinic cell carcinoma, cribriform cystadenocarcinoma, and adenocarcinoma, not otherwise specified (NOS), diagnosed over a 10-year period were retrieved from our surgical pathology files. There were a total of 11 cases diagnosed as acinic cell carcinoma, 10 cases of adenocarcinoma, NOS, and 6 cases of cribriform cystadenocarcinoma. All slides were reviewed by two pathologists (AP, CGF) and tumors that show morphologic features of mammary analog secretory carcinoma according to the recent literature were selected. This process narrowed down the initial number to six cases originally diagnosed as acinic cell carcinoma, three cases originally diagnosed as adenocarcinoma, NOS, and one case originally diagnosed as cribriform cystadenocarcinoma. The 10 cases were subjected to immunohistochemistry for S-100, mammaglobin, and ANO1, as well as fluorescence in situ hybridization analysis for t(12;15)(p13;q25) with ETV6-NTRK3 fusion rearrangement. The ETV6-NTRK3 gene rearrangement was detected in three tumors. These three tumors, initially diagnosed as acinic cell carcinomas, stained positive for S-100 and mammaglobin, and negative for ANO1 by immunohistochemistry. Two of the three patients were male (2/3). In summary, mammary analog secretory carcinoma is a newly described diagnostic entity that should be in the differential diagnosis of salivary gland tumors that morphologically mimic other neoplasms, mainly acinic cell carcinomas. They differ from conventional acinic cell tumors immunohistochemically and molecularly. Positivity for mammaglobin and S-100, and negativity for ANO1 are useful screening tools before confirmatory molecular studies.

Diagnosis and treatment of diffuse large B-cell lymphoma in an orangutan (Pongo pygmaeus).

Lymphoma is a common malignancy observed in companion animals. This type of naturally occurring neoplasia has been uncommonly reported in great apes. Diffuse large B-cell lymphoma was diagnosed in an 8-yr-old captive orangutan (Pongo pygmaeus) with gastrointestinal disease by histologic and immunohistochemical methodologies. The orangutan was treated with three cycles of combination chemotherapy (intravenous Rituxan, cyclophosphamide, doxorubicin, and vincristine). The primate has been in good health and exhibiting normal behaviors for more than 15 mo following treatment.

Frequent detection of parental consanguinity in children with developmental disorders by a combined CGH and SNP microarray.

BACKGROUND: Genomic microarrays have been used as the first-tier cytogenetic diagnostic test for patients with developmental delay/intellectual disability, autism spectrum disorders and/or multiple congenital anomalies. The use of SNP arrays has revealed regions of homozygosity in the genome which can lead to identification of uniparental disomy and parental consanguinity in addition to copy number variations. Consanguinity is associated with an increased risk of birth defects and autosomal recessive disorders. However, the frequency of parental consanguinity in children with developmental disabilities is unknown, and consanguineous couples may not be identified during doctor's visit or genetic counseling without microarray. RESULTS: We studied 607 proband pediatric patients referred for developmental disorders using a 4 × 180 K array containing both CGH and SNP probes. Using 720, 360, 180, and 90 Mb as the expected sizes of homozygosity for an estimated coefficient of inbreeding (F) 1/4, 1/8, 1/16, 1/32, parental consanguinity was detected in 21cases (3.46%). CONCLUSION: Parental consanguinity is not uncommon in children with developmental problems in our study population, and can be identified by use of a combined CGH and SNP chromosome microarray. Identification of parental consanguinity in such cases can be important for further diagnostic testing.

DNASE1L3 mutations in hypocomplementemic urticarial vasculitis syndrome.

OBJECTIVE: Hypocomplementemic urticarial vasculitis syndrome (HUVS) is characterized by recurrent urticaria along with dermal vasculitis, arthritis, and glomerulonephritis. Systemic lupus erythematosus (SLE) develops in >50% of patients with HUVS, although the pathogenesis is unknown. The aim of this study was to identify the causative DNA mutations in 2 families with autosomal-recessive HUVS, in order to reveal the pathogenesis and facilitate the laboratory diagnosis. METHODS: Autozygosity mapping was combined with whole-exome sequencing. RESULTS: In a family with 3 affected children, we identified a homozygous frameshift mutation, c.289_290delAC, in DNASE1L3. We subsequently identified another homozygous DNASE1L3 mutation leading to exon skipping, c.320+4delAGTA, in an unrelated family. The detected mutations led to loss of function, via either nonsense-mediated messenger RNA decay or abolished endonuclease activity, as demonstrated by a plasmid nicking assay. CONCLUSION: These results show that HUVS is caused by mutations in DNASE1L3, encoding an endonuclease that previously has been associated with SLE.

Molecular and genomic aberrations in Chlamydophila psittaci negative ocular adnexal marginal zone lymphomas.

The etiology and pathogenesis of ocular adnexal extranodal marginal zone lymphoma (OAEMZL) are still unknown and the association with Chlamydophila psittaci (C. psittaci) has been shown in only some geographic regions. Herein, we comprehensively examined the frequency of chromosomal translocations as well as CARD11, MYD88 (L265P), and A20 mutations/deletions in 45 C. psittaci negative OAEMZLs. t(14;18)(q32;q21) IGH-MALT1 and t(11;18)(q21;q21) API2-MALT1 were not detected in any of the analyzed tumors while three tumors harbored IGH translocations to an unidentified partner. CARD11 mutations were not found in all analyzed tumors, while the MYD88 L265P mutation was detected in three (6.7%) tumors. A20 mutations and deletions were each detected in seven (15.6%) and six (13.3%) tumors, respectively. Therefore, the observed genetic aberrations could account for the activation of the nuclear factor (NF)-kB signaling pathway in only a minority of the cases. Further studies are needed to identify the molecular mechanisms underlying the pathogenesis of OAEMZL.

Companion diagnostic testing for targeted cancer therapies: an overview.

Genes and their products involved in the biological pathways of human cancers have been studied as either targets of new therapies, or predictive markers for the sensitivity of or resistance to the therapies. Companion diagnostic testing on biological markers for targeted cancer therapies has become a vital component of personalized cancer treatment. This article provides an overview on the biological pathways and biomarkers, including EGFR, KRAS, BRAF, ALK, ROS1, HER2, and KIT for targeted treatment of lung, gastrointestinal, colorectal, and breast cancers as well as malignant melanoma. The current testing approach appears to focus on single biomarkers. However, a comprehensive approach that includes testing multimarkers involved in the mitogen-activated protein kinase, phosphoinositide 3-kinase/protein kinase B, and mammalian target of rapamycin pathways may become more desirable for some cancers, because of therapy resistance that can be caused by mutations in different genes and the availability of new therapies that may aim at multiple targets in the pathways. Only a few companion diagnostic kits have been approved by FDA, and the use of an FDA approved kit for some biomarkers, such as BRAF and KRAS, can be controversial.

Usefulness of HGAL and LMO2 immunohistochemistry in the identification of follicular lymphomas of the non-gastric gastrointestinal tract.

BACKGROUND: We studied the sensitivity of 2 relatively new markers of germinal center B-cell origin, namely human germinal center-associated lymphoma (HGAL) and Lim-only transcription factor 2 (LMO2), in the identification of follicular lymphomas (FLs) of the nongastric gastrointestinal (GI) tract. MATERIALS AND METHODS: We retrospectively reviewed cases of endoscopically derived primary, nongastric GI lymphomas including FL, grade 1 or 2, and extranodal marginal zone lymphoma (ENMZL) of mucosa-associated lymphoid tissue, classified based on morphologic features and immunohistochemical analysis. HGAL and LMO2 immunohistochemical stains were then prospectively performed in each case. When discrepant immunohistochemical results were obtained, fluorescent in situ hybridization was performed for t(14;18) IGH/BCL2 and IGH rearrangement using a dual color fusion and a dual color break-apart probe, respectively. RESULTS: All but one of the CD10-negative ENMZL cases were negative for both HGAL and LMO2. One case originally classified as ENMZL was positive for both HGAL and LMO2. Fluorescent in situ hybridization did not detect either t(14;18) IGH/BCL2 or IGH rearrangement in this case. It is likely, based on positivity of 2 established germinal center B-cell markers, that this represents a FL which was originally misclassified as an ENMZL based on CD10 negativity. Of the cases of FL (all CD10 and/or BCL-6 positive), 8 (80%) were positive for both HGAL and LMO2. CONCLUSIONS: Although HGAL and LMO2 did not demonstrate an increased sensitivity in the identification of FL of the nongastric GI tract in this series, they still were helpful in the reclassification of one of our cases, and may therefore be useful adjuncts in the identification of FL of the nongastric GI tract.