School of Medicine, University of Sarajevo, Sarajevo, Bosnia and Herzegovina Department of Pathology, Clinical Center, University of Sarajevo, Sarajevo, Bosnia and Herzegovina Department of Radiology, Clinical Center, University of Sarajevo, Sarajevo, Bosnia and Herzegovina Department of Oncology, Clinical Center, University of Sarajevo, Sarajevo, Bosnia and Herzegovina College of Medicine, Qatar University, Doha, Qatar

SUMMARY – Epithelioid hemangioendothelioma is a rare vascular brain tumor. It develops from endothelial cells, usually in the liver, lung, bone and soft tissue. Primary localization of this tumor in the intracranial space is very uncommon; only 47 cases have been described in the literature. This tumor was initially classified as grade I (benign) in the World Health Organization (WHO) 2007 classification. In 2016, this tumor was re-classified as grade III (malignant). Herein, the first case report of epithelioid hemangioendothelioma in the cerebellum of a male patient is presented. Complete surgical excision was done. No adjuvant therapy was administered. Magnetic resonance imaging performed 2 years after the surgery continued to show no recurrence of the tumor. To our knowledge, this is the first report of cerebellar location of this rare tumor. In addition, the authors report drastic re-classification of the epithelioid hemangioendothelioma from the benign tumor (WHO 2007) to a malignant one (2016), which significantly changes postoperative management and follow up of this brain neoplasm.

Incidence of breast cancer ranges from 27 per 100,000 in Middle Africa and Eastern Asia to 92 per 100,000 in Northern America. It is the fifth most common cause of death from cancer in women, with an estimated 522,000 deaths per year (6.4% of the total). Autosomal dominant inheritance of these cancers is characterized by transmission of cancer predisposition from generation to generation, with around 5-10% of all breast cancers being associated with inherited mutations in BRCA1, BRCA2 and other genes.  Breast and ovarian cancers are strongly associated with BRCA1 and BRCA2 mutations. In this study, we genotyped BRCA1 gene for large genomic rearrangements in breast and ovarian cancer patients from Bosnia and Herzegovina, with aim to assess frequency of large BRCA1 mutations (exon deletions/duplications) in this group. We collected 59 breast cancer samples, as well as other data concerning patients’ histopathological parameters of tumor, like age at diagnosis, cancer type, TNM class, cancer grade, as well as estrogen, progesterone and Her2/neu expression. Following DNA extraction from breast cancer samples (tissue after biopsy), BRCA1 mutations were identified by Multiplex Ligase - Dependent Probe Amplification (MLPA) analysis. Biostatistical analyses were conducted using MedCalc v.9.2.0.0 software. In all statistical tests p<0.05 was considered significant. Mean age at diagnosis was 54±1.75 (range 17 – 80). BRCA1 genomic rearrangements were found in 22% of breast and ovarian cancer patients. Statistically significant associations and correlations were found between BRCA1 genomic rearrangements and cancer type, estrogen, progesterone and Her2/neu expression, but not cancer grade, size, invasiveness or patients’ age

Incidence of breast cancer ranges from 27 per 100,000 in Middle Africa and Eastern Asia to 92 per 100,000 in Northern America. It is the fifth most common cause of death from cancer in women, with an estimated 522,000 deaths per year (6.4% of the total). Autosomal dominant inheritance of these cancers is characterized by transmission of cancer predisposition from generation to generation, with around 5-10% of all breast cancers being associated with inherited mutations in BRCA1, BRCA2 and other genes. Breast and ovarian cancers are strongly associated with BRCA1 and BRCA2 mutations. In this study, we genotyped BRCA1 gene for large genomic rearrangements in breast and ovarian cancer patients from Bosnia and Herzegovina, with aim to assess frequency of large BRCA1 mutations (exon deletions/duplications) in this group. We collected 59 breast cancer samples, as well as other data concerning patients’ histopathological parameters of tumor, like age at diagnosis, cancer type, TNM class, cancer grade, as well as estrogen, progesterone and Her2/neu expression. Following DNA extraction from breast cancer samples (tissue after biopsy), BRCA1 mutations were identified by Multiplex Ligase Dependent Probe Amplification (MLPA) analysis. Biostatistical analyses were conducted using MedCalc v.9.2.0.0 software. In all statistical tests p<0.05 was considered significant. Mean age at diagnosis was 54±1.75 (range 17 – 80). BRCA1 genomic rearrangements were found in 22% of breast and ovarian cancer patients. Statistically significant associations and correlations were found between BRCA1 genomic rearrangements and cancer type, estrogen, progesterone and Her2/neu expression, but not cancer grade, size, invasiveness or patients’ age. *Correspondence E-mail: naiad.lojo@ingeb.unsa.b a

In the early stages of cutaneous malignant melanoma (MM), it is extremely difficult to predict adequately the risk from hematogenic and lymphatic metastasis. We investigate whether the immunohistochemical expression of Ki-67 and estrogen receptor beta (ER&bgr;) in cells of MM could predict the status of regional lymph nodes. A total of 55 tissue samples of primary cutaneous melanomas with known status of regional lymph nodes were retrospectively evaluated for Ki-67 and ER&bgr; expression by quantitative immunohistochemistry and then correlated with the status of regional lymph nodes and relevant clinicopathologic parameters. The ER&bgr;-positive expression was detected in 38 of 55 tumors (69.09%). The Clark level showed a strong correlation with ER&bgr; expression, as well as pT stage. All cases of MM showed Ki-67-positive expression and an elevated Ki-67 expression was strongly associated with increased Breslow thickness, Clark level, ulceration, lymphovascular invasion, number of mitosis, and pT stage. Logistic regression analysis showed that when ER&bgr; levels increase by 1%, the risk of positive lymph nodes decreases by 7% (odds ratio=0.930; 95% confidence interval, 0.87-0.99; P=0.036), and, when the Ki-67 expression increases by 1%, the risk of lymph nodes’ positivity increases by 10% (odds ratio=1.108; 95% confidence interval, 1.02-1.19; P=0.009). Correlation between expression of Ki-67 and ER&bgr; and the status of lymph nodes has better prognostic significance than the relationship between melanoma thickness and the status of lymph nodes. Our study showed a significant prognostic value of Ki-67 expression in predicting the behavior of MM and the potential prognostic significance of ER&bgr;.

Targeted immunotherapy based on PD-1/PD-L1 suppression has revolutionized the treatment of various solid tumors. A remarkable improvement has also been observed in the treatment of patients with refractory/relapsing classical Hodgkin lymphoma (cHL). We investigated PD-L1 status in a variety of treatment resistant lymphomas. Tumor samples from 78 patients with therapy resistant lymphomas were immunohistochemically (IHC) investigated for the expression of PD-L1 using two antibody clones (SP142 and SP263, Ventana). Thirteen PD-L1+ cases were further analyzed for gene copy number variations (CNV) by NGS and for PD-L1/JAK2/PD-L2 co-amplification using fluorescent in-situ hybridization assay (FISH). PD-L1 positivity (≥5% positive cancer cells, IHC) was present in 32/77 (42%) and 33/71 cases (46%) using SP142 and SP263 antibodies, respectively. Concordance between the two anti-PD-L1 clones was high with only three (4%) discrepant cases. The strongest and consistent (10/11 cases) expression was observed in cHL and primary mediastinal B-cell lymphomas (3/3). Diffuse large B-cell lymphomas (DLBCL) were frequently positive (13/26) irrespective of subtype. Follicular (1/8), peripheral T-cell (3/11) and mantle cell (1/8) lymphomas were rarely positive, while small lymphocytic lymphoma/CLL and marginal zone lymphomas were consistently negative (3/3). Co-amplification/CNVs of PD-L1/JAK2/PD-L2 were observed in 3 cases of DLBCL and cHL, respectively. Of note, all three cHL-amplified cases were positive by FISH, but not by NGS. Since only a fraction of the IHC positive lymphoma cases were positive by FISH and NGS assays, other mechanisms are involved in PD-L1 upregulation, especially in DLBCL. FISH assay may be more suitable than NGS assay for determination of PD-L1 alterations in cHL.

Renal oncocytoma (RO) may present with a tubulocystic growth in 3% to 7% of cases, and in such cases its morphology may significantly overlap with tubulocystic renal cell carcinoma (TCRCC). We compared the morphologic and immunohistochemical characteristics of these tumors, aiming to clarify the differential diagnostic criteria, which facilitate the discrimination of RO from TCRCC. Twenty-four cystic ROs and 15 TCRCCs were selected and analyzed for: architectural growth patterns, stromal features, cytomorphology, ISUP nucleolar grade, necrosis, and mitotic activity. Immunohistochemical panel included various cytokeratins (AE1-AE3, OSCAR, CAM5.2, CK7), vimentin, CD10, CD117, AMACR, CA-IX, antimitochondrial antigen (MIA), EMA, and Ki-67. The presence of at least focal solid growth and islands of tumor cells interspersed with loose stroma, lower ISUP nucleolar grade, absence of necrosis, and absence of mitotic figures were strongly suggestive of a cystic RO. In contrast, the absence of solid and island growth patterns and presence of more compact, fibrous stroma, accompanied by higher ISUP nucleolar grade, focal necrosis, and mitotic figures were all associated with TCRCC. TCRCC marked more frequently for vimentin, CD10, AMACR, and CK7 and had a higher proliferative index by Ki-67 (>15%). CD117 was negative in 14/15 cases. One case was weakly CD117 reactive with cytoplasmic positivity. All cystic RO cases were strongly positive for CD117. The remaining markers (AE1-AE3, CAM5.2, OSCAR, CA-IX, MIA, EMA) were of limited utility. Presence of tumor cell islands and solid growth areas and the type of stroma may be major morphologic criteria in differentiating cystic RO from TCRCC. In difficult cases, or when a limited tissue precludes full morphologic assessment, immunohistochemical pattern of vimentin, CD10, CD117, AMACR, CK7, and Ki-67 could help in establishing the correct diagnosis.

Background Binding of PD-1 with ligands (e.g. PD-L1) expressed on tumor cells or native antigen-presenting cells results in down-regulation of effector T cell function and represents a potent mechanism of immune evasion across a number of solid tumors and lymphomas especially classical Hodgkin lymphoma (CHL) and aggressive virus-associated B-cell lymphomas. Several biomarkers (different antibodies, gene amplifications and mutations) are being investigated for identifying patients who may benefit from PD-1 checkpoint blockade therapies. It is well known that tumors which strongly express PD-L1 have a high clinical response rate to PD1 blockade. We aimed at identifying the expression of PD-L1 and PD1 in a diverse group of lymphomas. There are several antibodies used to detect PD-L1 expression, however the concordance between these antibodies is not known. We have previously tested concordance of 2 anti-PD-L1 antibodies in histiocytoses [1], but data in lymphomas are lacking. In the current study, we measured PD-L1 expression in lymphoma biopsy samples using 3 antibodies to identify if there was concordance in expression patterns of PD-L1 in various subtypes of lymphomas. Methods Formalin fixed paraffin embedded tissues from 37 patients with lymphomas of B- and T-cell lineages (both EBV-positive and negative) were investigated for the expression of PD-1 (MRQ-22 antibody) and PD-L1 (MAB1561, SP142 and SP263) using automated immunohistochemical methods. Expression of PD-L1 on 5% or more lymphoma cells was considered positive. Results Neoplastic cells expression of PD-L1 was identified in 13/37 cases (35% of all cases). The strongest (3+/>50% cells) and consistent (4/4 cases) expression was observed in Hodgkin RS cells of CHL (2/2 nodular sclerosis and 2/2 lymphocyte depleted). Other B-cell lineage lymphomas positive for expression of PD-L1 included diffuse large B-cell lymphomas (5/9 DLBCL) and lymphomatoid granulomatosis (1/1 LYG). Small lymphocytic lymphoma (n=3), splenic marginal zone lymphoma (n=2) and follicular lymphomas (n=8) were all negative. One of four mantle cell lymphomas (MCL) was borderline (5% of cells) positive. One NK/T-cell lymphoma was strongly (>50% cells) positive; four peripheral T-cell lymphomas (PTCL) and one T cell lymphoblastic lymphoma were negative. PD-L1 expression was observed in both EBV- positive (2/4) and negative (2/3) malignancies. Concordance between any 2 anti-PD-L1 antibodies varied between 86 and 97% (Table 1) with all 3 Abs agreeing in 82%. PD-1 was expressed on malignant cells in 3 cases (2 PTCL and 1 DLBCL); reactive PD-1+ T-lymphocytes were absent in LD CHL and variably present in all other lymphomas. Conclusions Over-expression of PD-L1was detected in classic HD, diffuse large B cell lymphoma, NK/T cell lymphoma and lymphomatoid granulomatosis. A high concordance in detection of PD-L1 between three antibodies indicates little need for companion diagnostic kits, but correlation between clinical responses and level of PDL1 and PD1 expression in lymphoma should be established in future clinical trials. | Antibodies (n) | MAB1561 | SP142 | SP263 | | -------------- | ----------- | ----------- | ----------- | | MAB1561 (23) | -- | 20/23 (86%) | | | SP142 (37) | -- | -- | 34/35 (97%) | | SP263 (35) | 19/22 (86%) | -- | -- | Table 1. Concordance between the PD-L1 antibodies. References: 1. Gatalica, Z., et al., Disseminated histiocytoses biomarkers beyond BRAFV600E: frequent expression of PD-L1. Oncotarget, 2015. Disclosures Gatalica: Caris Life Sciences: Employment. Arguello: Caris Life Sciences: Employment, Equity Ownership. Reddy: Caris Life Sciences: Employment. Ghosh: Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

The histiocytoses are rare tumors characterized by the primary accumulation and tissue infiltration of histiocytes and dendritic cells. Identification of the activating BRAFV600E mutation in Erdheim-Chester disease (ECD) and Langerhans cell histiocytosis (LCH) cases provided the basis for the treatment with BRAF and/or MEK inhibitors, but additional treatment options are needed. Twenty-four cases of neoplastic histiocytic diseases [11 extrapulmonary LCH, 4 ECD, 4 extranodal Rosai-Dorfman disease (RDD), 3 follicular dendritic cell sarcoma (FDCS), 1 histiocytic sarcoma (HS) and 1 blastic plasmacytoid dendritic cell neoplasm (BPDCN)] were analyzed using immunohistochemical and mutational analysis in search of biomarkers for targeted therapy. BRAF V600E mutations were detected in 4/11 LCH and 4/4 ECD cases. A pathogenic PTEN gene mutation and loss of PTEN protein expression were identified in the case of HS. Increased expression of PD-L1 (≥2+/≥5%) was seen in 3/4 ECD, 7/8 LCH, 3/3 FDCS and 1/1 HS, with overall 81% concordance between 2 antibodies used in the study (SP142 vs. MAB1561 clone). These results show for the first time significant expression of the PD-L1 immune checkpoint protein in these disorders, which may provide rationale for addition of immune check-point inhibitors in treatment of disseminated and/or refractory histiocytoses.

e22207 Background: Histiocytoses are rare tumors characterized by the primary accumulation of monocytes, macrophages and dendritic cells. The most frequent subtypes are Rosai-Dorfman disease (RDD), Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD) and follicular dendritic cell sarcomas (FDCS). Clinical presentations range from localized to disseminated, life threatening disease. Identification of an activating BRAFV600E mutation in the majority of ECD and LCH cases provided the basis for the use of BRAF and MEK inhibitors in these patients. Responses have been reported with BRAF inhibitors, but no curative treatment has yet been developed. Thus, additional targeted therapies are needed. Methods: Twenty-two cases (M:F = 13:9, age range 2-65 years) of histiocytic diseases (4 RDD, 10 LCH, 4 ECD, 2 FDCS, 1 histiocytic sarcoma [HS] and 1 blastic plasmacytoid dendritic cell neoplasm [BPDCN]) were analyzed using immunohistochemical and molecular methods (cobas 4800 BRAFV600 Mutation Test and The...

Background: Malignant melanoma (MM) is one of the tumors with fastest-growing incidence, also deadliest form of skin cancer. In the early stages of the disease it is extremely difficult to adequately predict risk from hematogenic and lymphatic metastasis. We assumed that the determination of Ki-67 and estrogen receptor beta (ER beta) in cells of MM could predict their biological behavior. Objectives: To examine whether the level of expression of Ki-67 and ER beta in cells of MM are in correlation with status of regional lymph nodes (LN), and compare the relationship between melanoma thickness (pT) and status of LN. Methods: Expression of Ki-67 and ER beta was examined by immunohistochemistry, and then staining positivity assessed and correlated with relevant clinical and pathological parameters. Results: Logistic regression analysis showed that when ER beta levels increase by 1% the risk of positive LN decreases by 7% (OR = 0.930, 95%CI 0.87–0.99, p = 0.036), and when the Ki67 expression increases by 1% that the risk of LN positivity increases by 10% (OR = 1.108, 95%CI 1.02 to 1.19, p = 0.009). Conclusions: Correlation between melanoma thickness and the status of LN has less prognostic significance than the relationship between expression of Ki-67 and ER beta and the status of LN. Our study showed a significant prognostic value of Ki67 expression in predicting the behavior of MM, and potential prognostic significance of ER beta.