Ewing sarcoma (ES) is a malignant round cell tumour (MRCT) that usually involves bone and soft tissue of young and paediatric populations. ES of the head and neck region is uncommon. Adamantinoma-like Ewing sarcoma (ALES) is a rare variant of ES that shows complex epithelial differentiation on histopathology and immunohistochemistry (IHC). It demonstrates a t(11;22) translocation and EWSR1-FLI1 fusion. Most documented cases of ALES of the head and neck region were initially misdiagnosed as epithelial tumours. We present a rare case of ALES of the nasal cavity in a young female. The patient subsequently underwent chemotherapy and showed an excellent response. Awareness of this entity is important for pathologists and oncologists due to its distinct therapeutic and prognostic implications. We propose performing upfront NKX2.2 and CD99 IHC studies, as well as other lineage specific IHC markers, in any poorly differentiated MRCT of head and neck region.
Context: Ewing sarcoma (ES) are malignant small round cell tumors (MSRCT) characterized by rearrangements of EWSR1 gene. Although gold standard for diagnosis is detection of specific fusion genes by molecular testing, these ancillary tests are costly and only available in limited number of settings. There is a persuasive evidence for reliability of NKX2.2 immunohistochemistry (IHC) as a surrogate marker for EWSR1 gene rearrangement in ES. Aims: The aim of this study is to correlate the NKX2.2 immuno-expression with genetically confirmed ES cases and also to assess the reliability and accuracy of NKX2.2 along with combined positivity of NXX2.2 and CD99 in diagnosing ES and differentiating it from other relevant histological mimics. Settings and Design: The present study is a retrospective study conducted over a period of 6-year duration in a tertiary cancer care center. Methods and Material: We evaluated NKX2.2 immunoexpression in 35 genetically confirmed cases of ES and also in pertaining differential entities (n = 58) of ES including rhabdomyosarcoma (n = 20), lymphoblastic lymphoma (n = 14), Wilms tumor (n = 10), poorly differentiated synovial sarcoma (n = 4), small-cell osteosarcoma (n = 4), neuroblastoma (n = 5), and mesenchymal chondrosarcoma (n = 1). CD99 was performed in the category of MSRCTs showing NKX2.2 positivity to evaluate combined specificity for the diagnosis of ES. Results: Of the 35 genetically confirmed cases of ES, 29 cases (83%) showed NKX2.2-positive expression (83% sensitivity). Compared to ES, NKX2.2 was positive in only 05% cases (3/58 cases) of non-ES MSRCT. Only two of five cases of neuroblastomas and one case of mesenchymal chondrosarcoma showed NKX2.2 positivity. CD99 positivity was seen in 100% of ES and in the single case of mesenchymal chondrosarcoma. All five cases (100%) of neuroblastoma were negative for CD99. Conclusions: The presented study, which is the first from an Indian oncology center, showed NKX2.2 IHC is quite reliable in diagnosis of ES in the right clinicopathological context. With remarkable sensitivity and specificity of NKX2.2 IHC for diagnosis of ES, we propose that combined positivity of CD99 and NKX2.2 IHC can obviate or minimize the need of EWSR1 gene rearrangement molecular testing for diagnosis of ES.
Objectives Cytological examination of cerebrospinal fluid is a widely used cost effective, simple procedure and a reliable routine diagnostic test. CSF cytology helps in detection of inflammatory diseases of the CNS, diagnosis of subarachnoid haemorrhage and the identification of malignant cells in metastatic or rarely primary CNS malignancies.Leptomeningeal metastases (LM) is estimated to occur in 5% of all patients with cancer. It has a higher propensity to occur in solid tumours compared to haematological malignancies.In view of poor prognosis, early diagnosis may aid in appropriate tumour staging and aggressive therapeutic intervention. Methods All the samples of CSF received in the Department of Laboratory for cytological examination and reported as ‘positive for malignant cells’ during the year January 2018 to December 2020were included in the study. All the cases were routinely evaluated on Neubauer’s chamber, direct smear and a cytospin preparation stained using MGG stain. The clinical records and any further ancillary testing performed were retrospectively analysed. Results 87cases with LM were identified over 3 year duration. Mean age of presentation was 43 years. Metastatic solid malignancies (56%) had a higher incidence of leptomeningeal metastases compared to haematolymphoid malignancies (40%) and CNS medulloblastomas(2%). Most common solid tumour with involvement of CSF was adenocarcinoma lung (51%) followed by breast carcinoma (37%). Of all the cases of adenocarcinoma lung with LM, EGFR mutant NSCLC were 40% while 8% showed ALK gene rearrangement. Amongst the haematological malignancies, acute leukaemia’s constituted 67% of cases while systemic NHLs were 34%. Most of the cases (97%) presented with neurological symptoms during the course of treatment while 3 cases (3%) showed LM at the time of first presentation. Conclusions With appropriate clinicoradiological correlation, CSF cytology remains the gold standard for identification of malignant cells in cases with already known primary tumour (leptomeningeal dissemination of the disease). In this study, clinical features of both solid and haematolymphoid malignancies were evaluated. The group of solid malignancies included adenocarcinomas lung, breast, gastrointestinal tract and renal cell carcinoma. With the availability of EGFR TKIs and ALK inhibitors, overall survival of the patients may be prolonged with therapeutic interventions despite limited CSF and CNS penetration of these drugs.
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