Background NUT carcinoma (NC) is an aggressive neoplasm that often presents with alarge tumor burden and metastases; cytology is frequently one of the primary diagnostic modalities. Primary pulmonary NCs are very rare and cytology descriptions are limited. The current study was performed to analyze the cytomorphological features of primary pulmonary NCs in different cytology samples and preparations. Methods A total of 15 cytology specimens from 10 patients with primary pulmonary NCs diagnosed primarily on histology were retrieved and reviewed. Results Fifteen cytology samples, including aspirates from primary (5 samples) and metastatic (5 samples) sites, sputum (1 sample), and effusions (4 samples), that were prepared as direct smears, centrifuged smears, and cell blocks were reviewed. Aspirate smears from all cases were cellular and demonstrated fragments and cohesive clusters of primitive tumor cells with scant cytoplasm, ovoid nuclei with coarse granular chromatin, and consistently conspicuous single nucleoli in a frequently neutrophil‐rich necrotic background with dispersed bare tumor nuclei. In fluid cytology, tight, 3‐dimensional tumor clusters and singly lying tumor cells were observed. Squamous differentiation in the form of sheets and singly lying polygonal tumor cells with abundant dense cytoplasm was noted focally in rare cases. The diagnoses during original sign‐outs were poorly differentiated carcinoma, poorly differentiated squamous cell carcinoma, and malignant small round cell tumor. NUT‐1 (NUT family member 1 protein) immunocytochemistry performed on cell blocks demonstrated characteristic speckled nuclear staining in tumor cells. Conclusions Pulmonary NC presents as a poorly differentiated carcinoma with focal to absent squamous differentiation on cytology. Cellular fragments of primitive tumor cells with conspicuous nucleoli should raise suspicion of NUT carcinoma and prompt ancillary testing.

Ependymomas (EPN) show site specific genetic alterations and a recent DNA methylation profiling study identified nine molecular subgroups. C11orf95-RELA and YAP1 fusions characterise the RELA and YAP1 molecular subgroups, respectively, of supratentorial (ST)-EPNs. Current guidelines recommend molecular subgrouping over histological grade for accurate prognostication. Clinicopathological features of ST-EPNs in correlation with C11orf95-RELA and YAP1 fusions have been assessed in only few studies. We aimed to study these fusions in EPNs, and identify diagnostic and prognostic markers. qRT-PCR and Sanger Sequencing for the detection of C11orf95-RELA, YAP1-MAMLD1 and YAP1-FAM118B fusion transcripts, gene expression analysis for NFKB1, and immunohistochemistry for p53, MIB-1, nestin, VEGF, and L1CAM were performed. 88 EPNs (10-Grade I and 78-Grade II/III) from all sites were included. RELA fusions were unique to Grade II/III ST-EPNs, detected in 81.4% (22/27) and 18.5% (5/27) of pediatric and adult ST-EPNs respectively. ST-EPNs harbouring RELA fusions showed frequent grade III histology (81.5%), clear cell morphology (70.3%), upregulated NFKB1 expression, MIB-1 labelling indices (LI) ≥ 10% (77.8%), and immunopositivity for nestin (95.7%), VEGF (72%), L1CAM (79%), and p53 (64%). Presence of RELA fusions, L1CAM immunopositivity and MIB-1 LI ≥ 10% associated with poor outcome. L1CAM showed 81% concordance with RELA fusions. YAP1-MAMLD1 fusion was identified in a single RELA fusion negative adult anaplastic ST-EPN. RELA fusions are frequent in ST-EPNs and associate with poor outcome. L1CAM is a surrogate immunohistochemical marker. RELA fusion positive ST-EPNs strongly express nestin indicating increased stemness. Further evaluation of the interactions between NFKB and stem cell pathways is warranted.

Ependymomas are relatively uncommon gliomas with poor prognosis despite recent advances in neurooncology. Molecular pathogenesis of ependymomas is not extensively studied. Lack of correlation of histological grade with patient outcome has directed attention towards identification of molecular alterations as novel prognostic markers. Recently, 1q gain has emerged as a potential prognostic marker, associated with decreased survival, especially in posterior fossa, high grade tumors. Cases of intracranial ependymomas were retrieved. Tumors were graded using objective criteria to supplement WHO grading. Fluorescence in situ hybridization for 1q gain was performed on formalin-fixed paraffin embedded sections. Eighty-one intracranial ependymomas were analyzed. Pediatric (76%) and infratentorial (70%) ependymomas constituted the majority. 1q gain was seen in 27 cases (33%), was equally frequent in children (34%) and adults (32%), supratentorial (37%) and infratentorial (32%) location, grade II (33%) and III (25%) tumors. Recurrence was noted in 24 cases and death in 7 cases with 5-year progression-free and overall-survival rates of 37% and 80%, respectively. Grade II tumors had a better survival than grade III tumors; histopathological grade was the only prognostically significant marker. 1q gain had no prognostic significance. 1q gain is frequent in ependymomas in Indian patients, seen across all ages, sites and grades, and thus is likely an early event in pathogenesis. The prognostic value of 1q gain, remains uncertain, and multicentric pooling of data is required. A histopathological grading system using objective criteria correlates well with patient outcome and can serve as an economical option for prognostication of ependymomas.

This is the largest series of primary skull bone tumors from India. Documentation of such a series will aid in approaching differential diagnosis of skull tumors in a systematic manner.

We present a case of tall cell variant of papillary carcinoma of thyroid diagnosed on cytology showing predominance of rosette‐like formations. Also described previously for the columnar cell variant, these rosettes need to be differentiated from micro‐follicles and are an indicator for aggressive variants.