Characteristic Staining Pattern Research Articles

Cross-sectional study to evaluate the utility of elastic tissue staining in primary cicatricial alopecia

Background and aimsDiagnosing end-stage primary cicatricial alopecia (PCA) on routine histology is challenging since the major diagnostic feature (inflammatory infiltrate) may be minimal or absent. This study aimed to assess...

Epithelioid Trophoblastic Tumor Predominant Mixed Germ Cell Tumor of the Testis: A Case Report and Review of the Literature.

An epithelioid trophoblastic tumor is a rare form of gestational trophoblastic neoplasia that mostly affects the uterus and endocervix in female patients of the reproductive age group. The tumor is believed to arise from chorion leave-type intermediate trophoblast. The epithelioid trophoblastic tumor in men is extremely rare and mostly described in association with mixed germ cell tumors of the testis. It is more commonly identified at the metastatic sites than in the testis. The epithelioid trophoblastic tumor should be differentiated from placental site trophoblastic tumor and squamous cell carcinoma. The distinctive morphology and characteristic immunohistochemical staining pattern help differentiate epithelioid trophoblastic tumors from other neoplasms. Only 7 male patients with epithelioid trophoblastic tumors have been described to date. Of these 7 patients, 4 were in metastatic sites, 2 in the testis, and 1 in the lung without the involvement of the testis or retroperitoneum. The proportion of epithelioid trophoblastic tumors was only 5% in the 2 patients with testis involvement. Here, we report the third patient with a primary testicular epithelioid trophoblastic tumor in a young man. Further, this is the first report to document epithelioid trophoblastic tumor as dominant histology in a testicular germ cell tumor.

Autosomal-dominant tubulointerstitial kidney disease with a novel UMOD mutation, overlapping with Sjogren's syndrome: a case report.

Autosomal-dominant tubulointerstitial kidney disease caused by UMOD (encoding uromodulin) mutation (ADTKD-UMOD) is a rare hereditary disease. A strong family history of hyperuricemia or gout and inherited kidney disease raises the suspicion of ADTKD-UMOD. Genetic testing can confirm the diagnosis without a kidney biopsy. However, when complicated by other diseases that can cause tubulointerstitial disease, renal biopsy is indispensable for the diagnosis and decisions on treatment strategy. We report the case of a 44-year-old woman referred for evaluation of kidney dysfunction. She had an attack of gout 1month before referral and a family history of hyperuricemia. She was diagnosed with primary Sjogren's syndrome through an immune workup and ophthalmological examination. However, a kidney biopsy revealed histological features suggesting ADTKD rather than gouty kidney or tubulointerstitial nephritis associated with Sjogren's syndrome, and immunostaining revealed a characteristic staining pattern with UMOD. Comprehensive genetic testing of 93 genes responsible for polycystic kidney disease revealed a novel heterozygous missense variant (c.649T > A:p. Cys217Ser) in UMOD, and the patient was diagnosed with ADTKD-UMOD. In this case, kidney biopsy contributed to the correct diagnosis of tubulointerstitial kidney disease. This case emphasizes the importance of suspecting ADTKD-UMOD based on family history and careful evaluation of kidney biopsy findings.

Ever Expanding Morphologic Patterns of Mesonephric-like Adenocarcinomas of the Uterine Corpus: A Report of Two Tumors and a Brief Review of the Literature.

Mesonephric-like adenocarcinoma (MLA) of the endometrium shows a variety of morphologic appearances, including small glands, tubules with eosinophilic materials in the lumen, prominent papillary patterns, spindled cells, solid formations, and corded and hyalinized patterns. Unique morphology, characteristic immunohistochemical staining patterns, molecular alterations, and awareness of the pathologists make it possible to identify this tumor accurately. This report of two additional morphologic patterns, intestinal goblet cells mimicking intestinal-type mucinous carcinoma and squamous differentiation with spindle and epithelioid cells mimicking carcinosarcoma of the endometrium will expand the literature on MLA.

Clinicopathologic Spectrum of Lysozyme-Associated Nephropathy

Lysozyme-associated nephropathy (LyN), a rare cause of kidney injury in patients with chronic myelomonocytic leukemia (CMML), has not been well described to date. We report the clinicopathologic spectrum of LyN from a multi-institutional series. We identified 37 native kidney biopsies with LyN and retrospectively obtained clinicopathologic data. Thirty-seven patients had a median age of 74 years and included 78% males. Their most common presentation was acute kidney injury (AKI) or AKI on chronic kidney disease (CKD) (66%) with median estimated glomerular filtration rate (eGFR) of 21.7 ml/min per 1.73 m2, and proteinuria of 1.7 g. A minority (15%) had partial Fanconi syndrome. Serum lysozyme levels were elevated in all tested. Hematologic disorder (n= 28, 76%) was the most common etiology, including CMML (n= 15), acute myeloid leukemia (n= 5), and myelodysplastic syndrome (MDS) (n= 5). Nonhematologic causes (n= 5, 14%), included metastatic neuroendocrine carcinoma (n= 3), sarcoidosis, and leprosy. Etiology was unknown in 4 (11%). Pathology showed proximal tubulopathy with abundant hypereosinophilic intracytoplasmic inclusions, with characteristic staining pattern by lysozyme immunostain. Mortality was high (8/30). However, among the 22 alive, including 85% treated, 7 had improved kidney function, including 1 who discontinued dialysis and 6 with increase in eGFR >15 ml/min per 1.73 m2 compared with eGFR at the time of biopsy. Increased awareness of the full clinicopathologic spectrum of LyN may lead to prompt diagnosis, earlier treatment, and potentially improved outcome of this rare entity.

Septin-3 autoimmunity in patients with paraneoplastic cerebellar ataxia

BackgroundSeptins are cytoskeletal proteins with filament forming capabilities, which have multiple roles during cell division, cellular polarization, morphogenesis, and membrane trafficking. Autoantibodies against septin-5 are associated with non-paraneoplastic cerebellar ataxia, and autoantibodies against septin-7 with encephalopathy with prominent neuropsychiatric features. Here, we report on newly identified autoantibodies against septin-3 in patients with paraneoplastic cerebellar ataxia. We also propose a strategy for anti-septin autoantibody determination.MethodsSera from three patients producing similar immunofluorescence staining patterns on cerebellar and hippocampal sections were subjected to immunoprecipitation followed by mass spectrometry. The identified candidate antigens, all of which were septins, were expressed recombinantly in HEK293 cells either individually, as complexes, or combinations missing individual septins, for use in recombinant cell-based indirect immunofluorescence assays (RC-IIFA). Specificity for septin-3 was further confirmed by tissue IIFA neutralization experiments. Finally, tumor tissue sections were analyzed immunohistochemically for septin-3 expression.ResultsImmunoprecipitation with rat cerebellum lysate revealed septin-3, -5, -6, -7, and -11 as candidate target antigens. Sera of all three patients reacted with recombinant cells co-expressing septin-3/5/6/7/11, while none of 149 healthy control sera was similarly reactive. In RC-IIFAs the patient sera recognized only cells expressing septin-3, individually and in complexes. Incubation of patient sera with five different septin combinations, each missing one of the five septins, confirmed the autoantibodies’ specificity for septin-3. The tissue IIFA reactivity of patient serum was abolished by pre-incubation with HEK293 cell lysates overexpressing the septin-3/5/6/7/11 complex or septin-3 alone, but not with HEK293 cell lysates overexpressing septin-5 as control. All three patients had cancers (2 × melanoma, 1 × small cell lung cancer), presented with progressive cerebellar syndromes, and responded poorly to immunotherapy. Expression of septin-3 was demonstrated in resected tumor tissue available from one patient.ConclusionsSeptin-3 is a novel autoantibody target in patients with paraneoplastic cerebellar syndromes. Based on our findings, RC-IIFA with HEK293 cells expressing the septin-3/5/6/7/11 complex may serve as a screening tool to investigate anti-septin autoantibodies in serological samples with a characteristic staining pattern on neuronal tissue sections. Autoantibodies against individual septins can then be confirmed by RC-IIFA expressing single septins.

A Case of Laryngeal Granular Cell Tumor

Granular cell tumors can occur at any body site. While in about a half of the cases, they arise in the head and neck region, occurrence in the larynx is rare. Based on their characteristic immunohistochemical staining patterns, granular cell tumors are thought to arise from Schwann cells. In all but a small percentage of cases, the tumors are benign. Multiple tumors in the body are seen in 10%-14% of cases. Herein, we report a case of granular cell tumor of the vocal cord.

Imaging of KCa 3.1 Channels in Tumor Cells with PET and Small-Molecule Fluorescent Probes.

The Ca2+ activated K+ channel KCa 3.1 is overexpressed in several human tumor cell lines, e. g. clear cell renal carcinoma, prostate cancer, non-small cell lung cancer. Highly aggressive cancer cells use this ion channel for key processes of the metastatic cascade such as migration, extravasation and invasion. Therefore, small molecules, which are able to image this KCa 3.1 channel in vitro and in vivo represent valuable diagnostic and prognostic tool compounds. The [18 F]fluoroethyltriazolyl substituted senicapoc was used as positron emission tomography (PET) tracer and showed promising properties for imaging of KCa 3.1 channels in lung adenocarcinoma cells in mice. The novel senicapoc BODIPY conjugates with two F-atoms (9 a) and with a F-atom and a methoxy moiety (9 b) at the B-atom led to the characteristic punctate staining pattern resulting from labeling of single KCa 3.1 channels in A549-3R cells. This punctate pattern was completely removed by preincubation with an excess of senicapoc confirming the high specificity of KCa 3.1 labeling. Due to the methoxy moiety at the B-atom and the additional oxyethylene unit in the spacer, 9 b exhibits higher polarity, which improves solubility and handling without reduction of fluorescence quantum yield. Docking studies using a cryo-electron microscopy (EM) structure of the KCa 3.1 channel confirmed the interaction of 9 a and 9 b with a binding pocket in the channel pore.

Development of the human ovary: Fetal through pubertal ovarian morphology, folliculogenesis and expression of cellular differentiation markers

A definition of normal human fetal and early postnatal ovarian development is critical to the ability to accurately diagnose the presence or absence of functional ovarian tissue in clinical specimens. Through assembling an extensive histologic and immunohistochemical developmental ontogeny of human ovarian specimens from 8 weeks of gestation through 16 years of postnatal, we present a comprehensive immunohistochemical mapping of normal protein expression patterns in the early fetal through post-pubertal human ovary and detail a specific expression-based definition of the early stages of follicular development. Normal fetal and postnatal ovarian tissue is defined by the presence of follicular structures and characteristic immunohistochemical staining patterns, including granulosa cells expressing Forkhead Box Protein L2 (FOXL2). However, the current standard array of immunohistochemical markers poorly defines ovarian stromal tissue, and additional work is needed to identify new markers to advance our ability to accurately identify ovarian stromal components in gonadal specimens from patients with disorders of sexual differentiation.

Abstract 255: Immunohistochemical Analysis Of Sars-cov-2 Induced Microvascular Thrombosis

Background: The SARS-CoV-2 virus utilizes Angiotensin Converting Enzyme 2 (ACE2) as the functional receptor for cellular entry. Additionally, SARS-CoV-2 binding induces downregulation of the ACE2 receptor, which creates an imbalance of the ACE/ACE2 ratio that promotes thrombosis. These factors can both potentially contribute to platelet aggregation and subsequent formation of cardiovascular microvascular thrombosis that can result in cardiac failure. Thus, identification of microthrombosis and analysis of the related molecular mediators can provide further understanding of SARS-CoV-2 pathophysiology. Methods: Heart autopsy specimens (N=23) from patients who died from cardiac failure due to COVID-19 complications and control heart tissue (N=5) were collected via rapid autopsy. These samples were sectioned and stained for H&E and MOVAT. Samples were then analyzed by immunohistochemistry (IHC) to identify the following inflammatory mediators, clotting factors, and related proteins: CD42b, C1Q, SARS-CoV-2 Spike protein, SARS-CoV-2 Nucleocapsid protein, ACE2 and Thrombin. Samples were then counterstained with DAPI and visualized with an ECHO Revolve Fluorescence Microscope. ImageJ was used to analyze pixel densities of immunofluorescence patterns compared to values obtained from control samples. Results: Histological analysis with H&E and MOVAT stains demonstrated diffuse microvascular thrombosis in cardiac samples from COVID patient. IHC staining revealed the significantly increased presence of SARS-CoV-2 Spike protein (p<0.0001), SARS-CoV-2 Nucleocapsid protein (p<0.0001), Thrombin (p<0.05), ACE2 Receptor (p<0.01), CD42b (p<0.01), C1Q (p<0.01). Furthermore, basement membrane staining was exceptionally characteristic with CD42B and Spike protein. Conclusions: This study demonstrates the effective use of immunohistochemistry in identification of various inflammatory mediators and clotting factors involved in the vascular pathophysiology of SARS-CoV-2. Replicated studies that provide further evidence of characteristic IHC staining patterns and the presence of additional thrombus-factors would strengthen our findings and deepen the understanding of SARS-CoV-2 pathophysiology.

Erythematous, telangiectatic nodule within the melomental fold

Erythematous, telangiectatic nodule within the melomental fold

Targeting Pyruvate Kinase M2 Phosphorylation Reverses Aggressive Cancer Phenotypes.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype with low survival rate and a lack of biomarkers and targeted treatments. Here, we target pyruvate kinase M2 (PKM2), a key metabolic component of oncogenesis. In patients with TNBC, PKM2pS37 was identified as a prominent phosphoprotein corresponding to the aggressive breast cancer phenotype that showed a characteristic nuclear staining pattern and prognostic value. Phosphorylation of PKM2 at S37 was connected with a cyclin-dependent kinase (CDK) pathway in TNBC cells. In parallel, pyruvate kinase activator TEPP-46 bound PKM2pS37 and reduced its nuclear localization. In a TNBC mouse xenograft model, treatment with either TEPP-46 or the potent CDK inhibitor dinaciclib reduced tumor growth and diminished PKM2pS37. Combinations of dinaciclib with TEPP-46 reduced cell invasion, impaired redox balance, and triggered cancer cell death. Collectively, these data support an approach to identify PKM2pS37-positive TNBC and target the PKM2 regulatory axis as a potential treatment. SIGNIFICANCE: PKM2 phosphorylation marks aggressive breast cancer cell phenotypes and targeting PKM2pS37 could be an effective therapeutic approach for treating triple-negative breast cancer.

Comparative analysis of BIOCHIP mosaic-based indirect immunofluorescence with direct immunofluorescence in diagnosis of autoimmune bullous diseases: A cross-sectional study

Background:Autoimmune bullous diseases (AIBD) are a heterogeneous group of diseases characterized by autoantibodies against desmosomal proteins in the pemphigus group of disorders and adhesion molecules of the dermal-epidermal junction in pemphigoid group of diseases. Direct immunofluorescence (DIF) establishes the diagnosis of AIBD by demonstrating intercellular deposits of IgG and C3 in case of pemphigus and linear deposits of IgG and C3 along the basement membrane zone (BMZ) in bullous pemphigoid (BP). BIOCHIP mosaic-based indirect immunofluorescence (IIF), a novel diagnostic approach employs detection of characteristic staining pattern and target antigens in a single miniature incubation field.Aim:To compare the BIOCHIP mosaic-based IIF with DIF in the diagnosis of AIBD.Materials and Methods:A total of 40 patients of AIBD in the active phase of the disease were included in the study. Skin biopsy was done in these patients for DIF study and serum was subjected to BIOCHIP mosaic-based IIF assay. The results were then compared.Results:DIF revealed a diagnosis of Pemphigus in 18 patients and BP in 22 patients. BIOCHIP showed a diagnosis of pemphigus in 18 patients, BP in 18 patients and floor pattern staining in four patients, which could be attributed to any of the floor pattern staining subepidermal blistering disease.Limitations:Small sample size, lack of control group and no comparison made with ELISA.Conclusion:This study concludes that the result of BIOCHIP shows correlation with the DIF and can be used as a first line-screening tool in the diagnosis of AIBD.

Sponge-like processed D-periodic self-assembled atelocollagen supports bone formation in vivo

Fibrous biopolymeric collagen extracted from animal tissues has been widely used for fabricating matrices for bone tissue engineering (BTE). However, animal extracted collagens can trigger immune reactions when implanted in vivo and the presence of native crosslinks leads to batch-to-batch variability. Atelocollagen, a monomeric form of collagen, is free of telopeptides, which are mainly responsible for the immunogenicity of collagen, and can self-assemble in vitro to obtain fibrils with the characteristic D-periodic staining pattern of native collagen. However, atelocollagen-based biomaterials have not extensively been studied and, hence, their suitability for BTE remains relatively unexplored. Besides, to stabilize collagen biomaterials, chemical and physical crosslinking are used, although chemical agents are cytotoxic while the physical methods yield a less effective crosslinking. A combination of physical and chemical crosslinking is a suitable alternative that has rarely been tested in BTE programs. In this work, a sponge-like biomaterial (DCol-S) was processed from D-periodic self-assembled atelocollagen and its stabilization was studied using the combination of a dehydrothermal treatment (DHT) and minimal glutaraldehyde (GTA) exposition crosslinking, to increase the resistance to degradation of the scaffold without a major effect on the biomaterial structure. The microstructural features of the final sponges were characterised and compared to a commercial biomaterial processed from native bovine collagen (Helistat®, Integra Lifesciences, NJ, USA), demonstrating that a D-periodic nanostructure was obtained and maintained after processing of the sponges. MC3T3-E1 preosteoblast adhesion, proliferation and differentiation assays in vitro showed that DCol-S is biocompatible. Furthermore, intramuscular implantation of the biomaterials loaded with rhBMP-2 revealed that the double-crosslinked sponges were able to support ectopic bone formation, while sponges stabilised only with the DHT treatment were not. Altogether, these findings show that atelocollagen-based sponges stabilised with a DHT treatment followed by a mild GTA crosslinking are a suitable alternative to polymeric extracted collagen for BTE applications.

EP18 Testicular sarcoidosis: a challenging diagnosis

EP18 Testicular sarcoidosis: a challenging diagnosis

Neuroblastoma patient-derived cultures are enriched for a mesenchymal gene signature and reflect individual drug response.

Ex vivo evaluation of personalized models can facilitate individualized treatment selection for patients, and advance the discovery of novel therapeutic options. However, for embryonal malignancies, representative primary cultures have been difficult to establish. We developed patient‐derived cell cultures (PDCs) from chemo‐naïve and post–treatment neuroblastoma tumors in a consistent and efficient manner, and characterized their in vitro growth dynamics, histomorphology, gene expression, and functional chemo‐response. From 34 neuroblastoma tumors, 22 engrafted in vitro to generate 31 individual PDC lines, with higher engraftment seen with metastatic tumors. PDCs displayed characteristic immunohistochemical staining patterns of PHOX2B, TH, and GD2 synthase. Concordance of MYCN amplification, 1p and 11q deletion between PDCs and patient tumors was 83.3%, 72.7%, and 80.0% respectively. PDCs displayed a predominantly mesenchymal‐type gene expression signature and showed upregulation of pro‐angiogenic factors that were similarly enriched in culture medium and paired patient serum samples. When tested with standard‐of‐care cytotoxics at human C max‐equivalent concentrations, MYCN‐amplified and non‐MYCN‐amplified PDCs showed a differential response to cyclophosphamide and topotecan, which mirrored the corresponding patients’ responses, and correlated with gene signatures of chemosensitivity. In this translational proof‐of‐concept study, early‐phase neuroblastoma PDCs enriched for the mesenchymal cell subpopulation recapitulated the individual molecular and phenotypic profile of patient tumors, and highlighted their potential as a platform for individualized ex vivo drug‐response testing.

Postmortem Diagnosis of Anaphylactic Shock by Histopathological Examination of Mast Cell

An autopsy for a fatal anaphylactic shock (AS) is not rare; however, postmortem diagnosis of anaphylaxis can be very challenging due to nonspecific macroscopic findings and absence of diagnostic tests except serum mast cell tryptase analysis. We tried to review the usefulness of histopathologic examination as an alternative method for the postmortem diagnosis of AS in this study. Immunohistochemical staining was carried out for detection of mast cells in 27 autopsy cases, including 7 AS cases, 5 false-positive cases, and 15 control cases at the National Forensic Service from January 2013 to May 2015, and the differences of mast cell counts and staining pattern were analyzed. The results revealed no differences in the number of mast cells among the three groups; however, a characteristic mast cell degranulation staining pattern was observed in the AS group and false-positive group. It can be conclusively inferred that the histopathologic examination could prove helpful in the postmortem diagnosis of AS, but it should serve as an ancillary option. Key Words: Anaphylaxis · Mast cells · Autopsy · Pathology

Colorectal cancer with invasive micropapillary components (IMPCs) shows high lymph node metastasis and a poor prognosis: A retrospective clinical study.

Objects:The present study aimed to identify the clinicopathological characteristics of colorectal cancer (CRC) with invasive micropapillary components (IMPCs) and the relationship between different amounts of micropapillary components and lymph node metastasis.Methods:A cohort of 363 patients with CRC who underwent surgical treatment in the Second Affiliated Hospital of Zhejiang University School of Medicine between January 2013 and December 2016 were retrospectively reviewed. We compared the clinicopathological characteristics, including survival outcomes and immunohistochemical profiles (EMA, MUC1, MLH1, MSH2, MSH6, and PMS2), between CRC with IMPCs and those with conventional adenocarcinoma (named non-IMPCs in this study). Logistic regression was used to identify the association between IMPCs and lymph node invasion. A multivariate analysis was performed using the Cox proportional hazard model to evaluate significant survival predictors.Results:Among 363 patients, 76 cases had IMPCs, including 22 cases with a lower proportion of IMPCs (≤5%, IMPCs-L) and 54 cases with a higher proportion (>5%, IMPCs-H). Compared to the non-IMPC group, the IMPC group (including both IMPC-L and IMPC-H) had a lower degree of tumor differentiation (P = .000), a higher N-classification (P = .000), more venous invasion (P = .019), more perineural invasion (P = .025) and a later tumor node metastasis (TNM) stage (P = .000). Only tumor differentiation (P = .031) and tumor size (P = .022) were different between IMPCs-L and IMPCs-H. EMA/MUC1 enhanced the characteristic inside-out staining pattern of IMPCs, whereas non-IMPCs showed luminal staining patterns. The percentage of mismatch repair deficiency (dMMR) in the non-IMPC group was much higher than that in the IMPC group (14.7% vs 4.7%). The overall survival time of patients with IMPCs was significantly less than that of patients with non-IMPCs (P = .002), then that of IMPCs-H was lower than that of IMPCs-L (P = .030). Logistic regression revealed that patients with IMPCs were associated with lymph metastasis, regardless of the proportion of IMPCs. Multivariate analysis demonstrated both IMPCs-L and IMPCs-H as negative prognostic factors.Conclusions:IMPCs are significantly associated with lymph node metastasis and poor outcome, and even a minor component (≤5%) may render significant information and should therefore be part of the pathology report.

Assessment of antinuclear antibodies by indirect immunofluorescence assay: report from a survey by the American Association of Medical Laboratory Immunologists.

The indirect immunofluorescence assay (IFA) using HEp-2 cell substrates is the preferred method by some for detecting antinuclear antibodies (ANA) as it demonstrates a number of characteristic staining patterns that reflect the cellular components bound as well as semi-quantitative results. Lack of harmonized nomenclature for HEp-2 IFA patterns, subjectivity in interpretation and variability in the number of patterns reported by different laboratories pose significant harmonization challenges. The main objectives of this study were to assess current practice in laboratory assessment of HEp-2 IFA, identify gaps and define strategies to improve reading, interpretation and reporting. We developed and administered a 24-item survey based on four domains: educational and professional background of participants, current practice of HEp-2 IFA testing and training, gap assessment and the perceived value of International Consensus on Antinuclear Antibody Patterns (ICAP) and other factors in HEp-2 IFA assessment. The Association of Medical Laboratory Immunologists (AMLI) and American Society for Clinical Pathology administered the survey from April 1 to June 30, 2018, to members involved in ANA testing. This report summarizes the survey results and discussion from a dry workshop held during the 2019 AMLI annual meeting. One hundred and seventy-nine (n = 179) responses were obtained where a significant number were clinical laboratory scientists (46%), laboratory directors (24%), supervisors (13%) or others (17%). A majority of respondents agreed on the need to standardize nomenclature and reporting of HEp-2 IFA results. About 55% were aware of the ICAP initiative; however, among those aware, a significant majority thought its guidance on HEp-2 IFA nomenclature and reporting is of value to clinical laboratories. To improve ICAP awareness and further enhance HEp-2 IFA assessment, increased collaboration between ICAP and the clinical laboratory community was suggested with emphasis on education and availability of reference materials. Based on these suggestions, future efforts to optimize HEp-2 IFA reading, interpretation and reporting would benefit from more hands-on training of laboratory personnel as well as continuous collaboration between professional organizations, in vitro diagnostic manufacturers and clinical laboratories.

A Case of Pseudomyogenic Hemangioendothelioma of the Lower Extremity

Pseudomyogenic hemangioendothelioma (PMH) is a rare vascular tumor and was recently recognized as a distinct entity. It has a predilection for young male adults and it frequently occurs in distal extremities. Although it is known to follow an indolent course, multi-focal presentation and local recurrence are common. PMH should be differentiated from epithelioid sarcoma, epithelioid hemangioendothelioma, dermatofibrosarcoma protuberans, and rhabdomyosarcoma. Its characteristic immunohistochemical staining pattern and recurrent translocation t(7:19)(q22:q13) are the basis for its diagnosis. Surgical excision is the mainstay treatment, although chemotherapy can be considered in non-operable patients. We present a rare case of a 40-year-old Korean male patient diagnosed with PMH through an excisional biopsy to facilitate the recognition PMH in the clinical practice.