Subungual melanoma with cartilaginous differentiation: Molecular insights.

Melanoma's rare capacity to undergo heterologous differentiation can create significant diagnostic challenges. The molecular mechanisms underlying this phenomenon are not well understood. We present an unusual case of subungual melanoma exhibiting extensive cartilaginous differentiation and provide insights into its molecular and cytogenomic features. Histopathologically, the tumor was predominantly composed of nodules of malignant cartilage in association with a smaller population of nested epithelioid to rhabdoid cells. Immunohistochemically, the tumor cells in both components were positive for S100, SOX10, and PRAME, and were negative for Melan-A and HMB-45. Molecular analysis by whole exome DNA sequence did not detect any pathogenic variants in genes commonly implicated in melanoma. Additional analysis by SNP chromosomal microarray revealed a complex genome characterized by numerous chromosomal losses and gains, including a homozygous deletion of the CDKN2A locus and a heterozygous deletion of the locus containing EXT2, a tumor suppressor implicated in hereditary multiple osteochondromas and secondary chondrosarcomas. This case underscores the importance of recognizing cartilaginous differentiation as a rare manifestation of melanoma, particularly at subungual sites, and suggests that at least some of these melanomas may be driven by non-canonical molecular pathways.

Acute myeloid leukemia cutis with KMT2A::MLLT3 fusion presenting with leonine facies.

A 63-year-old woman presented with plaques covering 60 % body-surface-area and leonine facies. Blood work showed no diagnostic aberrancies. Skin biopsy contained a malignant CD4+/CD56+ mononuclear cell population concerning for blastic plasmacytoid dendritic cell neoplasm. A later bone marrow biopsy confirmed AML with KMT2A::MLLT10 fusion detected by next-generation sequencing (NGS). This patient's LC preceded blood and marrow based symptoms of AML. NGS of the initial skin biopsy should be considered as part of diagnostic guidelines in cases with LC in the differential as this may have led to earlier diagnosis in this case and future cases.

Harnessing Innate Immunity to Treat Mycobacterium tuberculosis Infections: Heat-Killed Caulobacter crescentus as a Novel Biotherapeutic.

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), is a serious and devastating infectious disease worldwide. Approximately a quarter of the world population harbors latent Mtb infection without pathological consequences. Exposure of immunocompetent healthy individuals with Mtb does not result in active disease in more than 90% individuals, suggesting a defining role of host immunity to prevent and/or clear early infection. However, innate immune stimulation strategies have been relatively underexplored for the treatment of tuberculosis. In this study, we used cell culture and mouse models to examine the role of a heat-killed form of a non-pathogenic microbe, Caulobacter crescentus (HKCC), in inducing innate immunity and limiting Mtb infection. We also examined the added benefits of a distinct chemo-immunotherapeutic strategy that incorporates concurrent treatments with low doses of a first-line drug isoniazid and HKCC. This therapeutic approach resulted in highly significant reductions in disseminated Mtb in the lungs, liver, and spleen of mice compared to either agent alone. Our studies demonstrate the potential of a novel innate immunotherapeutic strategy with or without antimycobacterial drugs in controlling Mtb infection in mice and open new avenues for the treatment of tuberculosis in humans.

Indolent B-cell lymphoma with t(14;19) investigated from a molecular perspective.

T(14;19) is an unusual but distinct genomic alteration reported in low-grade B-cell lymphomas. This structural rearrangement places BCL3 in juxtaposition with IGH inducing proliferation and has been found in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), marginal zone lymphoma (MZL), and other low-grade B-cell lymphomas. While there are some case series describing this in the context of other cytogenetic alterations, there are limited clinical cases examined from a molecular perspective. We herein describe a case of a low-grade B-cell lymphoma with t(14;19) resulting in IGH::BCL3 fusion on which we performed whole exome sequencing to investigate genetic variants that could contribute to its pathogenesis. We found pathogenic alterations including a variant in CXCR4 which has been shown to be recurrently mutated in different low-grade B-cell lymphomas including lymphoplasmacytic lymphoma (LPL) and MZL. We describe this interesting case in the context of its genomic findings and how it contributes to the literature as a whole.

Post-scabietic nodules: Mimicker of infantile indeterminate cell histiocytosis and potential diagnostic pitfall.

Indeterminate cell histiocytosis (ICH) is an extremely rare disease and little is known about its etiology. Patients usually present with nodular, dermal proliferations of indeterminate cells, which characteristically resemble Langerhans cells but lack Birbeck granules. The clinical course is highly variable, ranging from spontaneous regression to rapid progression with reports of extracutaneous involvement, subsequent acute myeloid leukemias, and associated B-cell lymphomas. Rare cases of ICH-like reactions have been reported in the setting of scabies infestations as well as in patients who had been bitten by ticks and mosquitos. We present a successfully treated case of indeterminate cell-rich post scabietic nodules in an otherwise healthy 8-month-old boy and review the literature on similar cases. Clinical context is essential for correct interpretation of these indolent ICH-mimicking lesions, and to avert unnecessary patient anxiety and aggressive management.

Pure erythroid leukemia, presenting with pancytopenia. Images in Hematology.

Pure erythroid leukemia is an aggressive form of acute leukemia, presenting with pancytopenia. It is defined as a neoplasm of erythroid lineage without a significant myeloblastic component, representing >80% of marrow, with 30% or more proerythroblasts. The disease has a rapid clinical course with median survival of only 3 months.

Variant allele frequencies do not correlate well with myeloblast counts in a clinically validated gene sequencing panel for routine acute myeloid leukemia workup.

Next generation sequencing (NGS) has introduced new types of data, such as variant allele frequencies (VAFs), into the workup of acute myeloid leukemias (AML). There is interest in using NGS to prognosticate disease behavior and monitor residual disease, but the attribution of sequencing data entirely to the leukemic clone may be confounded by VAF contribution from background non-leukemic populations and undetected copy number aberrations. Sixty-eight patients with AML were evaluated by a clinically validated gene sequencing panel at our institution from 2015 to 2018. No correlation was found with a direct comparison of blast counts and VAFs in both primary- and secondary-AML (R2 = 0.0584 and 0.0235, respectively). Only moderate correlations were attained when evaluating against mutant NPM1 allele fraction alone (R2 = 0.5303) or when variants with allelic frequencies >55% of the blast burden were excluded (R2 = 0.4608). VAFs from regular clinical-use gene sequencing panels show poor unrestricted correlation with leukemic blast proportions in AML.

Intravascular Large B-Cell Lymphoma Within a Thyroid Nodule: A Diagnostic Pitfall.

Intravascular large B-cell lymphoma (IVLBCL) is a subtype of diffuse large B-cell lymphoma, where the neoplastic lymphoid proliferation resides predominantly within the lumens of blood vessels but with no or few circulating neoplastic cells in the peripheral circulation. Focal or subtle involvement in some cases can cause the diagnosis to be misinterpreted or even overlooked, delaying the initiation of appropriate treatment. Our report focuses on a 78-year-old woman with a progressively enlarging thyroid mass, verified by ultrasound. She underwent a hemithyroidectomy, and microscopic evaluation demonstrated nodular thyroid parenchyma with atypical large cells in an intravascular distribution pattern identified on high magnification. Thorough evaluation showed that the large intravascular cells were positive CD20, PAX-5, and Ki-67 by immunoperoxidase staining, which lead to the diagnosis of IVLBCL. This case emphasizes the subtle appearance of IVLBCL, which may be missed on low-power light microscopy, and the need for careful evaluation of thyroid resection specimens.

BRAF V600E Mutation Across Multiple Tumor Types: Correlation Between DNA-based Sequencing and Mutation-specific Immunohistochemistry.

The B-Raf proto-oncogene (BRAF) encodes a cytoplasmic serine/threonine kinase with a key role in regulating the mitogen-activated protein kinase signal transduction pathway. An activating missense mutation in codon 600 of exon 15 (V600E) of BRAF gene has been identified in multiple neoplasms including melanoma, colorectal carcinoma, papillary thyroid carcinoma, hairy cell leukemia, and Langerhans cell histiocytosis. Patients with BRAF V600E-mutated melanoma respond to FDA-approved BRAF inhibitors. In addition, subsets of other BRAF V600E-mutated tumors may also benefit from BRAF inhibitor therapy. Currently, clinical laboratories typically use molecular-based methods for mutation analysis. However, recently a BRAF V600E mutation-specific antibody has become available as a cost-effective alternative method to DNA-based molecular testing. We analyzed multiple tumor types including melanoma, colorectal carcinoma, papillary thyroid cancer, hairy cell leukemia, and Langerhans cell histiocytosis using both DNA-based sequencing and the BRAF V600E mutation-specific antibody. Our results show a high degree of concordance between the 2 methods. However, the high concordance seems to be limited only to the V600E mutation since variant V600 mutations are missed by V600E mutation-specific immunohistochemistry.

Monoamine oxidase A is highly expressed in classical Hodgkin lymphoma.

Monoamine oxidase A (MAOA) is a mitochondrial enzyme that catalyzes oxidative deamination of neurotransmitters and dietary amines and produces H2 O2 . It facilitates the progression of gliomas and prostate cancer, but its expression and functional relevance have not been studied in lymphoma. Here, we evaluated MAOA in 427 cases of Hodgkin and non-Hodgkin lymphoma and in a spectrum of reactive lymphoid tissues by immunohistochemistry on formalin-fixed, paraffin-embedded specimens. MAOA was expressed by Hodgkin Reed-Sternberg (HRS) cells in the majority of classical Hodgkin lymphomas (cHLs) (181/241; 75%), with 34.8% showing strong expression. Weak MAOA was also noted in a minority of primary mediastinal large B-cell lymphomas (8/47; 17%) and in a mediastinal gray-zone lymphoma. In contrast, no MAOA was found in non-neoplastic lymphoid tissues, nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL; 0/8) or any other non-Hodgkin lymphomas studied (0/123). MAOA was more common in Epstein-Barr virus (EBV)-negative compared to EBV-positive cHL (p < 0.0001) and was especially prevalent in the EBV-negative nodular sclerosing subtype. Similar to primary human lymphoma specimens, most cHL-derived cell lines displayed MAOA activity, whereas non-Hodgkin-lymphoma-derived cell lines did not. The MAOA inhibitor clorgyline reduced the growth of L1236 cells and U-HO1 cells, and shRNA knockdown of MAOA reduced the growth of L1236 cells. Conversely, ectopic overexpression of MAOA increased the growth of MAOA-negative HDLM2 cells. Combined treatment with clorgyline and ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine) was more effective in reducing cell growth than either regimen alone. In summary, MAOA is highly expressed in cHL and may reflect the distinct biology of this lymphoma. Further studies on the potential utility of MAOA as a diagnostic marker and therapeutic target are warranted. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

HLA expression and HLA type associations in relation to EBV status in Hispanic Hodgkin lymphoma patients.

A proportion of classical Hodgkin lymphomas harbor the Epstein Barr virus (EBV). We previously demonstrated that associations between Human Leukocyte Antigen (HLA) alleles and susceptibility to EBV+ classical Hodgkin lymphoma differ between European and Chinese populations. Data on Hispanic populations is missing. Here we examined the association between HLA type, tumor cell HLA expression and other characteristics in Hispanic Hodgkin lymphoma patients. Hispanic Hodgkin lymphoma patients diagnosed at the Los Angeles County-University of Southern California Medical Center from 2000-2012 were included (n = 65). Formalin-fixed paraffin-embedded tumor tissue was analyzed for EBV by in situ hybridization and for HLA class I and class II expression by immunohistochemistry. HLA typing was performed by HLA-A specific quantitative PCR of genomic DNA from tissue. Thirty patients (46%) had EBV+ tumors. Expression of HLA class I (p = 0.0006) was significantly associated with EBV+ tumor status in Hispanic patients, similar to Europeans and Chinese. A positive association between HLA class II expression and EBV+ tumor status, as present in large studies in Europeans, was not found (p = 0.06). The prevalences of the specific European HLA-A*01 risk and European HLA-A*02 protective types were not significantly associated with EBV+ tumors among these Hispanic patients, however numbers were too low to draw firm conclusions. The HLA-A*02:07 allele, that is associated with EBV+ Hodgkin lymphoma in Chinese, was absent. In conclusion, the association between EBV positivity in tumor cells and HLA class I expression appears to be consistent across different populations. Larger studies in Hispanics are needed to evaluate HLA allele susceptibility associations.

Plasmablastic lymphoma mimicking carcinomatosis: A case report and review of the literature.

First identified as a distinct disease entity in HIV-positive patients, plasmablastic lymphoma is a rare aggressive disease which arises predominantly in men and is associated with immunodeficiency of all causes. Although its exact etiology is poorly understood, Epstein-Barr virus infection and MYC gene aberrations have been implicated in its development in both HIV-positive and HIV-negative patients. The disease typically involves extranodal sites with a predilection for the oral cavity but may occur in other locations. Here we present a case of plasmablastic lymphoma diffusely involving the omentum and peritoneal cavity of an immunocompetent woman, clinically mimicking an ovarian carcinomatosis. To the best of our knowledge, this is the first case in which plasmablastic lymphoma has presented as peritoneal lymphomatosis. Diagn. Cytopathol. 2017;45:243-246. © 2016 Wiley Periodicals, Inc.

Isodicentric Philadelphia chromosome: an uncommon chromosomal abnormality in the chronic phase of chronic myeloid leukemia (CML).

An isodicentric Philadelphia chromosome is an uncommon finding previously described as a secondary chromosomal abnormality in accelerated- or blast-phase of chronic myeloid leukemia (CML) with resistance to imatinib mesylate or dasatinib. Here, we present a case with idic(Ph) chromosome identified at initial diagnosis in a patient with chronic-phase CML.

Processing the lymph node biopsy.

The testing modalities available and necessary to precisely diagnose lymphadenopathies, lymphadenitides, and lymphomas are numerous. However, to much chagrin, the tissue samples submitted for evaluation are frequently limited in size. Consequently, the triage of each individual lymph node sample with judicious apportionment of tissue for diagnostic testing has become of paramount importance. We describe a practical approach to processing the lymph node specimen to maximize the diagnostic utility of the sample provided.

Acute myeloid leukemia with t(7;21)(p22;q22) and 5q deletion: a case report and literature review.

The gene RUNX1 at chromosome 21q22 encodes the alpha subunit of Core binding factor (CBF), a heterodimeric transcription factor involved in the development of normal hematopoiesis. Translocations of RUNX1 are seen in several types of leukemia with at least 21 identified partner genes. The cryptic t(7;21)(p22;q22) rearrangement involving the USP42 gene appears to be a specific and recurrent cytogenetic abnormality. Eight of the 9 cases identified in the literature with this translocation were associated with acute myeloid leukemia (AML), with the remaining case showing refractory anemia with excess blasts, type 2. Herein, we present a patient with two preceding years of leukopenia and one year of anemia prior to the diagnosis of AML, NOS with monocytic differentiation (myelomonocytic leukemia) whose conventional cytogenetics showed an abnormal clone with 5q deletion. Interphase FISH using LSI RUNX1/RUNXT1 showed three signals for RUNX1. FISH studies on previously G-banded metaphases showed the extra RUNX1 signal on the short arm of chromosome 7. Further characterization using the subtelomeric 7p probe showed a cryptic 7;21 translocation. Our case and eight previously reported leukemic cases with the t(7;21)(p22;q22) appear to share similar features including monocytic differentiation, immunophenotypic aberrancies (often with CD56 and/or CD7), and a generally poor response to standard induction chemotherapy. About 80% of these cases had loss of 5q material as an additional abnormality at initial diagnosis or relapse. These findings suggest that t(7;21) may represent a distinct recurrent cytogenetic abnormality associated with AML. The association between the t(7;21) and 5q aberrancies appears to be non-random, however the pathogenetic connection remains unclear. Additional studies to evaluate for RUNX1 partner genes may be considered for AML patients with RUNX1 rearrangement and 5q abnormalities; however knowledge of the prognostic implications of this rearrangement is still limited.