Richard D. Hammer

Immunohistochemical Detection of Cyclin D1 Using Optimized Conditions Is Highly Specific for Mantle Cell Lymphoma and Hairy Cell Leukemia

Mantle cell lymphoma (MCL) is more aggressive when compared with other lymphomas composed of small, mature B lymphocytes. Cyclin D1 is overexpressed in MCL as a result of the translocation t(11;14)(q13;q32). Cyclin D1 immunohistochemistry in fixed, paraffin-embedded tissue contributes to the precise and reproducible diagnosis of MCL without the requirement of fresh tissue. However, its use in bone marrow biopsies is not well established. In addition, increased levels of cyclin D1 mRNA have been found in hairy cell leukemia but have not consistently been detected by immunohistochemistry. We used a polyclonal antibody and heat-induced antigen retrieval conditions to evaluate 73 fixed, paraffin-embedded bone marrow, spleen, and lymph node specimens with small B-cell infiltrates, obtained from 55 patients. Cyclin D1 was overexpressed in 13/13 specimens of MCL (usually strong, diffuse reactivity in most tumor cells) and in 14/14 specimens of hairy cell leukemia (usually weak, in a subpopulation of tumor cells). No reactivity was detected in five cases of B-chronic lymphocytic leukemia; five cases of splenic marginal zone lymphoma; six cases of nodal marginal zone cell lymphoma; two cases of gastric marginal zone cell lymphoma; or ten benign lymphoid infiltrates in bone marrow, spleen, or lymph nodes. In summary, although the total number of studied cases is small and a larger series of cases may be required to confirm our data, we present optimized immunohistochemical conditions for cyclin D1 in fixed, paraffin-embedded tissue that can be useful in distinguishing MCL and hairy cell leukemia from other small B-cell neoplasms and reactive lymphoid infiltrates.

Somatic mutation analysis of IgH variable regions reveals that tumor cells of most parafollicular (monocytoid) B-cell lymphoma, splenic marginal zone B-cell lymphoma, and some hairy cell leukemia are composed of memory B lymphocytes.

The cell of origin of parafollicular (monocytoid) B cell lymphoma (PBCL), splenic marginal zone lymphoma (SMZL), and hairy cell leukemia (HCL) is controversial. To better understand the relationship between these low-grade B-cell neoplasms, we analyzed the nucleotide sequences of the rearranged immunoglobulin heavy (IgH) chain variable (V) region of the clonal population of cells in five cases of PBCL, four cases of SMZL, and seven cases of HCL to determine whether these neoplasms could be differentiated by the degree of somatic mutation in the IgH V gene or by the IgH V gene family usage. DNA was extracted from diagnostic material and clonality confirmed by PCR. The DNA was reamplified using V heavy chain family specific primers, and the amplicons were sequenced. Sequences were compared with germline IgH V gene sequences, and base changes were determined to be silent or to represent amino acid replacements by using three different methods. Four of five (80%) cases of PBCL, three of four (75%) cases of SMZL, and three of seven (43%) cases of HCL showed evidence of antigen selection, suggesting that these neoplasms involved clonal expansions of postgerminal center memory lymphocytes. Only SMZL showed a preferential usage of V(H)1 family genes.

Splenic marginal zone lymphoma. A distinct B-cell neoplasm.

The splenic marginal zone is a morphologically and perhaps immunologically distinct B-cell compartment. Lymphomas arising from cells of the splenic marginal zone are rare. Here we describe the morphologic, immunologic, and clinical features of 14 cases. Patient age ranged from 35 to 79 years (median, 68 years) with a male-to-female ratio of 1:1.8. The spleen was uniformly enlarged (median, 1,540 g; range, 388-3,845 g) in all patients, the neoplastic infiltrate had a nodular pattern in three cases, nodular and diffuse in seven cases, and diffuse in four cases. The neoplastic cells had small to medium-sized nuclei with round, oval, or slightly indented contours, small eosinophilic nucleoli, and a moderate amount of pale cytoplasm. Extrasplenic involvement was present in 12 patients. Lymph nodes often had a vaguely nodular pattern and preservation of sinuses; bone marrow was infiltrated focally (seven cases) or diffusely (one case). Five patients had hepatic involvement. Ultrastructurally, neoplastic cells differed from other small B cells and resembled normal marginal zone cells by having long, serpentine rough endoplasmic reticulum profiles. All lymphomas marked as B cells and light chain restriction was demonstrated in 12 cases. Bcl-2 protein expression was present in all cases. Most cases (70%) were negative for DBA.44 (CD72). Plasmacytic differentiation was present in three cases. In conclusion, splenic marginal zone lymphoma is a B-cell neoplasm with distinctive clinical, morphologic, immunologic, and ultrastructural characteristics.

Impact of Consensus Conference Review on Diagnostic Disagreements in the Evaluation of Cervical Biopsy Specimens

Objectives To determine the impact of consensus conferences on the frequency of discrepant cases in a surgical pathology practice. Methods The percentage of discrepancies in cases reviewed at a weekly consensus conference was calculated for the first and last months of a 13-month period. Both interrater agreement and agreement with the consensus diagnoses were assessed. A total of 309 diagnoses were performed for the first month and 518 for the last month. Both absolute and chance-corrected agreement were calculated for each period. Results Absolute agreement rate increased from 91.2% in the first month to 98.2% in the final month. Chance-corrected agreement increased from 0.80 in the first month to 0.97 in the final month. Conclusions The consensus conference technique appears to be a useful method to reduce intradepartmental diagnostic discrepancies. Both absolute and chance-corrected agreement are improved by using consensus conferences.

A Biphasic Pleural Tumor with Features of an Epithelioid and Small Cell Mesothelioma: Morphologic and Molecular Findings

Malignant mesotheliomas are generally classified into epithelioid, sarcomatoid, desmoplastic, and biphasic types with rare reports of a small cell form. These small cell variants display some morphologic overlap with desmoplastic small round cell tumors (DSRCTs) which generally occur within the abdominal cavity of young males and are defined by a characteristic t(11;22)(p13;q12) translocation. However, there are rare reports of DSRCTs lacking this translocation. We present a 78-year-old man with a pleura-based biphasic neoplasm with features of both epithelioid mesothelioma and a small cell blastema-like neoplasm. The epithelioid portion showed IHC reactivity for pan cytokeratin, CK5/6, D2-40, and calretinin and the small cell portion marked with CD99, pan cytokeratin, WT1, FLI1, S100, CD200, MyoD1, and CD15. Fluorescence in situ hybridization testing for the t(11;22)(p13;q12) translocation disclosed loss of the EWSR1 gene in 94% of tumor cell nuclei, but there was no evidence of the classic translocation. Array based-comparative genomic hybridization (a-CGH) confirmed the tumor had numerous chromosome copy number losses, including 11p15.5-p11.12 and 22q12.1-q13.33, with loss of the EWSR1 and WT1 gene regions. Herein, we report novel complex CGH findings in a biphasic tumor and review the molecular genetic alterations in both mesothelioma and DSRCTs.

Abstract 5625: Identification and validation of a PD-L1 specific peptide for determination of PD-L1 expression in tumors

In recent years, immunotherapy has seen a resurgence as a promising method of treating cancers. The interaction between Programmed Death Ligand 1 (PD-L1) and its receptor, Programmed Death 1 receptor (PD-1) has been of particular interest. Many different types of tumors have been shown to overexpress PD-L1, which causes host immune cells that express the PD-1 receptor and bind PD-L1 to cease killing the tumor. Patients who have tumors exhibiting high levels of PD-L1 show poor prognosis compared to those who do not. Inhibition of the PD-L1 PD-1 binding axis has been shown to restore host immunity to the tumor, and recently many new drugs such as atezolizumab and pembrolizumab have been developed to target this interaction. Current methods of PD-L1 diagnosis have shown to vary based on the antibody, detection kit brand, antigen retrieval method, and clinically strict defined methods for use by the FDA for assessment. To refine detection of PD-L1, we have identified a PD-L1 specific peptide which can be used to detect PD-L1 expressing tumors using either conventional immunohistochemistry or flow cytometry. Immunohistochemistry using this peptide was tested against the FDA-approved PD-L1 (SP263) Rabbit monoclonal primary antibody on biopsied patient tissues. Flow cytometry was performed on both cultured cell lines and patient tissues. We have shown that our PD-L1 peptide shows specific staining in the tumor regions of FFPE tissues where the SP263 kit does not stain, and we can also detect PD-L1 expression in both cell samples and patient tissues using flow cytometry. Citation Format: Charles Caldwell, Cory Johnson, Richard Hammer, Raghuraman Kannan. Identification and validation of a PD-L1 specific peptide for determination of PD-L1 expression in tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5625. doi:10.1158/1538-7445.AM2017-5625