Immunohistochemistry for LEF1 and SOX11 adds diagnostic specificity in small B-cell lymphomas.

Lymphocyte enhancer-binding factor 1 (LEF1) and SRY-Box 11 (SOX11) are highly sensitive and specific for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and mantle cell lymphoma (MCL) including the cyclin D1-negative subtype, respectively. We assessed the utility of these markers in a large cohort of small B-cell lymphomas (SBCLs) on varied sample types. Immunohistochemistry (IHC) was performed for LEF1 and SOX11 on 354 SBCLs (129 CLL/SLLs, 33 MCLs, 142 marginal zone lymphomas [MZLs]-nodal MZL [NMZL]: 40, extranodal MZL [ENMZL]: 28, splenic MZL [SMZL]: 74 cases-and 50 lymphoplasmacytic lymphomas [LPLs]/Waldenstrom macroglobulinemias [WMs]). Ninety-eight percent of CLL/SLLs were LEF1 positive. SOX11 showed good sensitivity (82%) and excellent specificity for MCL (99%), with only 2 of 142 MZLs (both SMZLs) showing SOX11 expression. The low sensitivity for SOX11 was on account of inclusion of 4 non-nodal cases. All 50 LPL/WMs were negative for both LEF1 and SOX11. The expression of SOX11 and LEF1 was not always mutually exclusive, as 2 confirmed MCLs expressed both markers. LEF1 and SOX11 have excellent utility as diagnostic markers especially for atypical CD5-positive SBCLs.

Genetic and Clinical Studies of Patients With Increased Multinucleated Megakaryocytes in Bone Marrow as an Isolated Finding: A Diagnostic Pitfall for Myelodysplastic Syndrome.

The presence of increased multinucleated megakaryocytes (aka osteoclast-like) is considered a dysplastic feature in myelodysplastic syndrome; however, its clinical significance in isolation is uncertain. Herein, we report the clinicopathologic and genetic features of 18 such cases of 40,539 bone marrow biopsies spanning 10 years. All 18 patients had ≥25% multinucleated megakaryocytes in otherwise normal bone marrow biopsies, which were evaluated for plasma cell neoplasms (n=9), lymphoma (n=4), or anemia/neutropenia (n=5). None of the 17 patients tested showed acquired cytogenetic abnormalities. Sixteen patients underwent targeted gene panel next-generation sequencing: 9 patients had no pathogenic mutations; 3 harbored a single pathogenic mutation with variant allele frequencies of 7.5%, 7.6%, and 10.7%, likely representing clonal hematopoiesis of indeterminate potential; 1 had 2 pathogenic mutations, 1 of which had a variant allele frequency >20%. Fourteen of 18 patients had a follow-up period >6 months (median: 36.5 mo, range: 7 to 110 mo) and no patients developed a new-onset cytopenia, a progressive cytopenia, or a myeloid neoplasm. The patient with 2 mutations had persistent anemia, worrisome for an emerging MDS. However, given the absence of thrombocytopenia, increased multinucleated megakaryocytes in this patient could be an unrelated incidental finding. Our study indicates that increased multinucleated megakaryocytes as an isolated finding is a rare phenomenon, and this sole morphologic finding is not diagnostic of myelodysplastic syndrome. Diagnostic approaches in the presence of increased multinucleated megakaryocytes are proposed based on different clinical and pathologic scenarios.

Mixed-phenotype large granular lymphocytic leukemia: a rare subtype in the large granular lymphocytic leukemia spectrum.

Large granular lymphocytic leukemia (LGLL) is a chronic proliferation of cytotoxic lymphocytes in which more than 70% of patients develop cytopenia(s) requiring therapy. LGLL includes T-cell LGLL and chronic lymphoproliferative disorder of natural killer (NK) cells. The neoplastic cells in LGLL usually exhibit a single immunophenotype in a patient, with CD8-positive/αß T-cell type being the most common, followed by NK-cell, γδ T-cell, and CD4-positive/αß T-cell types. We investigated a total of 220 LGLL cases and identified 12 mixed-phenotype LGLLs (5%): 7 cases with coexistent αß T-cell and NK-cell clones and 5 with coexistent αß and γδ T-cell clones. With a median follow-up of 48 months, the clinicopathological characteristics of these patients seemed similar to those of typical LGLL patients. Treatment was instituted in 9 patients, and 5 patients (55%) attained complete hematologic response or partial response. The therapeutic response rate of this cohort is comparable to the reported overall response rate of 40% to 60% in typical LGLL patients. Three patients who did not receive any treatment had progressive or persistent cytopenias. Interestingly, inverted proportions of 2 clones at disease recurrence were identified in 4 patients (36%) and stable clonal proportions in 7 patients (64%). Mixed-phenotype LGLL is rare, and this study underscores the importance of recognizing this rare type of LGLL in patients who may benefit from LGLL treatment.

Nodular Lymphocyte Predominant Hodgkin Lymphoma of the Ileum.

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a rare lymphoma derived from germinal center B lymphocytes that typically presents with localized lymph node involvement and can mimic a variety of both reactive and other neoplastic conditions. Extranodal involvement is uncommon in NLPHL and typically occurs in the context of previously documented or synchronous nodal disease. Involvement of the gastrointestinal tract is exceedingly rare. Here, we present the first case to our knowledge of NLPHL involving the ileum that was discovered incidentally on routine screening colonoscopy in an asymptomatic patient. An awareness of the spectrum of clinical presentations, careful morphologic evaluation, and a comprehensive panel of immunohistochemical stains are essential for correct diagnosis of NLPHL presenting in unusual anatomic sites.

BCR-JAK2 fusion in a myeloproliferative neoplasm with associated eosinophilia.

Janus kinase 2 (JAK2) is located on chromosome 9 at band p24 and JAK2V617F is the most common mutation in Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-MPN). However, rearrangement of JAK2 is a rare event. We report a case of myeloproliferative neoplasm, unclassifiable (MPN-U) with BCR-JAK2 fusion confirmed by molecular studies. Conventional chromosome analysis (CC) revealed t(9;22)(p24;q11.2) and fluorescence in situ hybridization (FISH) showed a JAK2 gene rearrangement in 88% of interphase nuclei. The BCR-JAK2 fusion was confirmed by multiplex reverse transcriptase polymerase chain reaction (RT-PCR) and demonstrated two in-frame 5'BCR/3'JAK2 transcripts with BCR exon 1 juxtaposed to JAK2 exon 15 and exon 17, respectively. Our results, together with literature review, reveal BCR-JAK2 fusions as oncogenic genetic alterations that are associated with myeloid or lymphoid neoplasms and are frequently characterized by eosinophilia. Further, patients with BCR-JAK2 are candidates for JAK2 inhibitor therapy. Given the distinct clinical and pathological characteristics, we believe that hematological neoplasms harboring BCR-JAK2 should be included as an additional distinct entity to the current WHO category of "myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB, or FGFR", and testing for a JAK2 fusion should be pursued in neoplasms with a karyotypic 9p24 abnormality.

Aberrant crypt focus and fragile histidine triad protein in sporadic colorectal carcinoma.

AIM: To characterize aberrant crypt focus (ACF) in adjoining mucosa in sporadic colorectal carcinoma and to evaluate fragile histidine triad (Fhit) protein and Ki67. METHODS: ACF was identified grossly and classified histologically in 75 resected specimens. ACF was typed into hyperplastic ACF (HACF) and dysplastic ACF (DACF). Sections of ACF, carcinoma and normal colonic mucosa as control were studied for Fhit and Ki67 expressions by immunohistochemistry and were grouped according to staining intensity and the number of positive stained cells observed in different histological groups. Comparison was done between the different groups by Pearson's χ(2) test and γ test for the ordinal data. P value < 0.05 was considered as significant. RESULTS: Age range was 40 to 86 years in males (mean = 43.36) and 45 to 70 years in females (mean = 56). HACF was identified in all cases studied in the non-tumorous colonic mucosa; ACF was observed as non-contiguous scattered foci, which supports the hypothesis of acquisition of single focus monoclonality by colonic epithelial cells in tumor generation. Twenty-four (32%) had DACF and were observed as closure to carcinoma foci. Intensity of Fhit expression: (1) HACF - 40% exhibited strong intensity, similar to normal, moderate in 36% and weak in 24%; (2) DACF - strong in 25%, moderate in 37.5% and weak in 37.5%; and (3) carcinoma - negative in 16%, strong in 43% and moderate and weak in 28.5% each. Significant difference was observed in intensity of the Fhit protein expressions by HACF and DACF (P < 0.05). Tumor in older patients showed a stronger Fhit intensity compared to younger patients (P = 0.036). Vegetarian diet intake and non-smokers showed stronger Fhit intensities. Advanced stage tumor, non-vegetarian diet and younger age was associated with loss of Fhit protein. Ki67 positivity was an extended crypt pattern in HACF and DACF showed extension up to the neck region of the crypts and surface epithelium. Carcinomas showed a marked increase in Ki67 expression (P < 0.05). Fhit protein had an inverse association with Ki67 expression. CONCLUSION: Weaker Fhit intensity was associated with smoking, non-vegetarian diet intake and increasing Ki67 expression. Loss of Fhit protein expression is possibly influenced by environmental factors like smoking and non-vegetarian diet intake.

Florid plasmacytosis in a case of acute myeloid leukemia: A diagnostic dilemma.

The association of acute myeloid leukemia (AML) with plasmacytosis is a known, although rare event. There are very few case reports documenting an increase in the number of plasma cells at the time of AML diagnosis. Here, we present the case of a 65-year-old male diagnosed as acute myelomonocytic leukemia with exuberant plasmacytosis, which posed a difficulty in diagnosis. Paracrine interleukin-6 production by leukemic blast cells is thought to contribute to this associated reactive plasma cell proliferation.

Ascitic fluid cytology and flow cytometry in the primary diagnosis of lymphoma - a case report.

Primary diagnosis of lymphomas from ascitic fluid is rare. We report a case in which a patient being worked up as a case of carcinoma head of pancreas turned out to be a lymphoma on routine ascitic fluid examination and was further sub-classified as a CD 10+ B-cell lymphoma on flow cytometric analysis.

The role of immunohistochemistry in medullomyoblastoma--a case series highlighting divergent differentiation.

AIMS: To analyse the histo-morphology of cases of medullomyoblastoma and identifying its divergent differentiation. METHODS: A retrospective review of all cases reported as medulloblastoma between the period of Jan 2000 to Dec 2006 was carried out on Hematoxylin and eosin (H & E) stained slides. The cases were screened on light microscopy for primitive neuroectodermal component of a medulloblastoma accompanied by areas of "myoid" differentiation, identified on the basis of presence of strap cells (indicating a clear skeletal muscle differentiation) and/or large anaplastic cells with vescicular nuclei and moderate to abundant amount of eosinophilic cytoplasm. All these cases were subjected to a panel of immunohistochemical stains, including Desmin, GFAP, NFP, HMB45, SMA, S100, CK and EMA. Ultrastructural analysis was done on tissue obtained from paraffin blocks in 2 cases. RESULTS: Male predominance (M:F = 5:1) was noted with an incidence of five percent of all cases of medulloblastoma (6 out of 120 cases) over a period of 6 years. Primitive neuroectodermal areas were accompanied with areas of "myoid" differentiation, 5 cases showing strap cells. Two cases with epithelial and cartilaginous differentiation were seen. Three cases showed focal melanocytic differentiation, identified only on HMB45 immunostaining. Four cases showed glial differentiation. Neuronal differentiation again was very focally seen in two cases, of which one was identified only by NFP immunostain. Seventh case is included in the study, however it is not considered to calculate incidence as it occurred beyond the period of 6 years of records search. CONCLUSION: Medullomyoblastoma is a rare childhood tumor of cerebellum. Majority of cases reveal divergent differentiation, which are identified with the help of panel of immunostains indicating multi-potential nature of primitive neuroectodermal cells.