Kavneet Kaur

Integrating Molecular Subclassification of Medulloblastomas into Routine Clinical Practice: A Simplified Approach

Medulloblastoma (MB) is composed of four molecular subgroups viz. WNT, SHH, groups 3 and 4, identified using various high‐throughput methods. Translation of this molecular data into pathologist‐friendly techniques that would be applicable in laboratories all over the world is a major challenge. Ninety‐two MBs were analyzed using a panel of 10 IHC markers, real‐time PCR for mRNA and miRNA expression, and FISH for MYC amplification. β‐catenin, GAB1 and YAP1 were the only IHC markers of utility in classification of MBs into three subgroups viz. WNT (9.8%), SHH (45.6%) and non‐WNT/SHH (44.6%). mRNA expression could further classify some non‐WNT/SHH tumors into groups 3 and 4. This, however, was dependent on integrity of RNA extracted from FFPE tissue. MYC amplification was seen in 20% of non‐WNT/SHH cases and was associated with the worst prognosis. For routine diagnostic practice, we recommend classification of MBs into three subgroups: WNT, SHH and non‐WNT/SHH, with supplementation by prognostic markers like MYC for non‐WNT/SHH tumors. Using this panel, we propose a new three‐tier risk stratification system for MBs. Molecular subgrouping with this limited panel is rapid, economical, works well on FFPE tissue and is reliable as it correlates significantly with clinicopathological parameters and patient survival.

c-Myb Overexpression in Cytology Smears of Tracheobronchial and Pulmonary Adenoid Cystic Carcinomas

Aims: Adenoid cystic carcinoma (AdCC) is a malignant epithelial neoplasm that occurs rarely in the lower respiratory tract (LRT). AdCC at various sites is associated with the novel fusion transcript MYB-NFIB, along with the overexpression of the Myb protein. The expression of the Myb protein in AdCC of the LRT has not been evaluated much. Study Design: Cases of AdCC of the LRT diagnosed on cytology or histology were retrieved from our institutional archives. c-Myb expression was analyzed on immunocytochemistry/immunohistochemistry (ICC/IHC) and was correlated with clinicopathological parameters. Results: Twenty-three samples of AdCC originating from the LRT were included in the study. Four cases were diagnosed on cytology, 3 of which had corresponding histology specimens. The remaining 19 cases had either biopsy or resection. Most of the patients presented with endobronchial mass. The mean age was 49.4 years and a male predominance was seen. ICC and IHC for c-Myb showed positivity in 75 and 59% of the cases, respectively. Western blot was used to validate IHC results. Conclusion: AdCC of the LRT is rare and hence poses diagnostic difficulty. Cytology smears can be utilized for c-Myb ICC. The presence of c-Myb immunopositivity in most cases may possibly make Myb a diagnostic biomarker and a therapeutic target for personalized treatment.

Pelvic mature cystic teratoma with neuroendocrine carcinoma: report of a rare association and review of literature.

Extra-gonadal malignant transformation of teratoma is rare and there are only a few reports available citing malignancy arising in the non-germ cell components. We hereby report a case of a 35-year-old female, who presented with lower backache with a radiologically identifiable mass lesion in the pre-sacral region. Clinical and radiological findings suggested the possibility of a cystic teratoma. Histopathological examination and relevant immunohistochemical tests detected a mature cystic teratoma with features of a grade 2 neuroendocrine tumor in it. Like the index case, most of the previously reported cases of teratoma with malignant transformation of the somatic components were found in extra-gonadal site. This case is being reported to emphasize that any extra-gonadal mass in reproductive age group, even if it appears radiologically and per-operatively benign, must be subjected to histopathological examination to rule out possibility of malignant transformation of the germ cell or non-germ cell components.

Adenocarcinoma predominant pattern subtyping and nuclear grading in cytology: Is there a role in prognostication of advanced pulmonary adenocarcinomas?

Primary lung adenocarcinomas (ADs) show varied architectural patterns, and pattern‐based subtyping of ADs is currently recommended due to prognostic implications. Predicting AD patterns on cytology is challenging; however, cytological nuclear features appear to correlate with histological grade and survival in early stage lung ADs. The feasibility and value of AD pattern prediction and nuclear grading on cytology in advanced lung ADs is not known. We aimed to predict patterns and analyse nuclear features on cytology and evaluate their role in prognostication.

Loss-of-Function Mutations in Calcitonin Receptor (CALCR) Identify Highly Aggressive Glioblastoma with Poor Outcome

Purpose: Despite significant advances in the understanding of the biology, the prognosis of glioblastoma (GBM) remains dismal. The objective was to carry out whole-exome sequencing (WES) of Indian glioma and integrate with that of TCGA to find clinically relevant mutated pathways. Experimental Design: WES of different astrocytoma samples (n = 42; Indian cohort) was carried out and compared with that of TCGA cohort. An integrated analysis of mutated genes from Indian and TCGA cohorts was carried out to identify survival association of pathways with genetic alterations. Patient-derived glioma stem-like cells, glioma cell lines, and mouse xenograft models were used for functional characterization of calcitonin receptor (CALCR) and establish it as a therapeutic target. Results: A similar mutation spectrum between the Indian cohort and TCGA cohort was demonstrated. An integrated analysis identified GBMs with defective “neuroactive ligand–receptor interaction” pathway (n = 23; 9.54%) that have significantly poor prognosis (P < 0.0001). Furthermore, GBMs with mutated calcitonin receptor (CALCR) or reduced transcript levels predicted poor prognosis. Exogenously added calcitonin (CT) inhibited various properties of glioma cells and pro-oncogenic signaling pathways in a CALCR-dependent manner. Patient-derived mutations in CALCR abolished these functions with the degree of loss of function negatively correlating with patient survival. WT CALCR, but not the mutant versions, inhibited Ras-mediated transformation of immortalized astrocytes in vitro. Furthermore, calcitonin inhibited patient-derived neurosphere growth and in vivo glioma tumor growth in a mouse model. Conclusions: We demonstrate CT–CALCR signaling axis is an important tumor suppressor pathway in glioma and establish CALCR as a novel therapeutic target for GBM. Clin Cancer Res; 24(6); 1448–58. ©2017 AACR.

Neuroblastoma-like schwannoma of the skull base: an enigmatic peripheral nerve sheath tumor variant.

Neuroblastoma‐like schwannoma is an extremely rare histological variant of schwannoma, which histologically mimics a malignant small round cell tumor. Only 19 cases have been reported in the literature to date. We report a case of this tumor located at the skull base in a 44‐year‐old woman who presented with symptoms of right‐sided earache and hearing loss. MRI revealed a large, lobulated, extra‐axial mass measuring 8.8 cm × 3.6 cm × 4.2 cm in the floor of the middle and posterior cranial fossa. Microscopic examination revealed a perplexing histopathology with peculiar collagenous rosettes. Differential diagnoses included a broad range of benign and malignant tumors. Typical schwannoma seldom poses a difficulty in diagnosis; however, this unusual variant is a diagnostic challenge which requires an extensive clinico‐radiological correlation and immunohistochemical work‐up. Hence, knowledge of this entity is a must to avoid erroneous diagnosis and inappropriate treatment.

Primary diffuse large B-cell lymphoma of the prostate: A report of two cases with diagnostic considerations

Primary prostatic lymphomas are extremely unusual neoplasms. Their rarity and nonspecific symptomatology at presentation usually prompt a clinical diagnosis of benign prostatic hyperplasia or chronic prostatitis, leading to significant delay in diagnosis. Clinical examination, serum prostate-specific antigen levels, and transrectal ultrasonography (TRUS) are not of much utility in differential diagnosis, and histological examination is the gold standard. We report two cases of primary non-Hodgkin lymphoma of prostate, diffuse large B-cell type, diagnosed on TRUS-guided prostatic biopsies. Correct diagnosis is of crucial importance as the therapeutic strategy for lymphoma is radically different from that for carcinoma, and early detection of prostatic lymphoma can be potentially curative. Thus, knowledge of this rare entity, inclusion in differential diagnosis of lower urinary tract obstruction, and application of an appropriate immunohistochemical panel are essential so as not to miss this unusual diagnosis and to avoid unnecessary surgery.

Melanotic neuroectodermal tumour of infancy: An enigmatic tumour with unique cytomorphological features

Melanotic neuroectodermal tumour of infancy is an exceptionally rare tumour with <400 cases reported in literature. This enigmatic tumour primarily affects infants ( 80%) in the first year of life (<6 months). It most commonly involves the head and neck region ( 93%) with a predilection for maxilla (60%-80%). Other sites are rarely affected and include epididymis, peripheral bones, skull, brain and fontanelles. Historically, it has always fascinated pathologists and been given an assortment of names including retinal anlage tumour, melanotic progonoma, pigmented ameloblastoma, melanotic adamantinoma, retinal choristoma and atypical melanoblastoma. Histogenesis of this peculiar tumour remains elusive. It comprises two distinct population of cells: melanin-containing large, polygonal cells resembling melanocytes; and small round blue cells. Electron microscopic studies have demonstrated melanin granules and modified tight junctions, suggesting a relationship to malignant melanoma. Some authors have hypothesised an origin from neural crest cells, as the tumour morphologically recapitulates the development of retinal epithelium. The identification of BRAFV600E mutation in melanoma has paved the way for new targeted therapies such as vemurafenib and dabrafenib in metastatic malignant melanoma. Gomes et al reported BRAFV600E mutation in one of the two MNTI samples with interpretable sequencing results; having implications on personalised medicine. Although the histopathological features are well described, there are only few case reports describing cytomorphological details in the literature. We discuss here one such case with emphasis on cytological features along with review of available literature. Based on the morphological and reported pathogenetic overlap of MNTI with malignant melanoma, we in addition investigated BRAF-MEK-ERK pathway in the case. 2 | CASE REPORT

Abstract 2454: Genetic landscape of glioma reveals defective neuroactive ligand receptor interaction pathway as a poor prognosticator in glioblastoma patients

Glioblastoma (GBM; grade IV), is highly proliferative, infiltrative and treatment refractory. Hence, understanding the complete genetic alteration profile of GBM would help us in identifying molecules or pathways that have strong implications in GBM pathogenesis, thus opening up avenues for targeted therapy. Recent large scale studies suggest that three pathways - receptor-tyrosine kinase, TP53 and RB, are significantly altered in GBM. However, even with the tremendous increase in our understanding of the tumor, advancement in therapeutics is minimal and the median survival still remains at 15 months. Hence, we need to elucidate novel altered molecules and pathways in GBM progression such that more effective therapeutic options can be explored. Here, we have carried out whole exome sequencing of grade II, grade III and GBM samples which revealed the mutation spectrum of glioma from our patient set. Further, we performed integrative analysis of mutated genes from our patient cohort as well as TCGA cohort (The Cancer Genome Atlas) to find out mutated pathways that predict survival in GBM patients. The most significant pathway - neuroactive ligand-receptor interaction pathway was explored further. Patients with mutations in one or more genes of this pathway had poor survival. The pathway comprises of G-protein coupled receptors, ion channels and ligands which functions in modulation of neural plasticity, memory processes, behavior etc. Of the enriched genes belonging to this pathway, Calcitonin Receptor (CALCR), which was highest mutated in GBM (2.75%), was taken up for further investigation. CALCR was found to be downregulated in GBM and mutation or downregulation of the gene was found to predict poor survival in patients. Functional studies through cell-line based experiments revealed CALCR is a tumor suppressor in GBM. The peptide hormone calcitonin (CT), a high affinity CALCR ligand, inhibited proliferation, migration and anchorage-independent growth of glioma cells expressing CALCR with a concomitant decrease in the phosphorylation levels of ERK, AKT and JNK signaling molecules. However, CT failed to do these functions in CALCR silenced glioma cells. Exogenous overexpression of CALCR in glioma cells expressing low levels of the receptor was found to inhibit proliferation, migration and anchorage independent growth and this effect was further augmented when CT was added. Further, introduction of tumor-derived mutations in CALCR led to the abrogation of its tumor suppressor function. Studies are ongoing to demonstrate the tumor suppressive nature of CALCR using in vitro astrocyte transformation and intracranial orthotopic mouse glioma model. Thus, our study finds CT-CALCR signaling axis is an important tumor suppressor pathway in glioma development and underscores the importance of using CT as a novel therapeutic molecule for GBM treatment. Citation Format: Jagriti Pal, Vikas Patil, Anupam Kumar, Kavneet Kaur, Chitra Sarkar, Kumaravel Somasundaram. Genetic landscape of glioma reveals defective neuroactive ligand receptor interaction pathway as a poor prognosticator in glioblastoma patients [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 2454. doi:10.1158/1538-7445.AM2017-2454

Intracranial interhemispheric osteochondrolipoma: Diagnostic and surgical challenges in an extremely rare entity

Intracranial lipomas are rare developmental lesions, predominantly occurring in the interhemispheric location. Osteochondrolipoma is an extremely rare variant of lipoma with osseous and chondroid differentiation. We present a case of interhemispheric osteochondrolipoma, in a 2.5‐years‐old male child which was detected antenatally, in association with corpus callosum agenesis. The lesion progressively increased in size with resulting compression of surrounding structures, and was subjected to microsurgical decompression. To the best of our knowledge, this is the first case of intracranial interhemispheric osteochondrolipoma in the existing medical literature. Peculiarities of this case and the diagnostic and surgical challenges are discussed.