Evaluation of programmed cell death ligand 1 expression in a contemporary cohort of penile squamous cell carcinoma and its correlation with clinicopathologic and survival parameters: A study of 134 patients.

OBJECTIVES: Penile squamous cell carcinomas (PCs) are rare malignancies with a dismal prognosis in a metastatic setting; therefore, novel immunotherapeutic modalities are an unmet need. One such modality is the immune checkpoint molecule programmed cell death ligand 1 (PD-L1). We sought to analyze PD-L1 expression and its correlation with various clinicopathologic parameters in a contemporary cohort of 134 patients with PC. METHODS: A cohort of 134 patients with PC was studied for PD-L1 immunohistochemistry. The PD-L1 expression was evaluated using a combined proportion score with a cutoff of 1 or higher to define positivity. The results were correlated with various clinicopathologic parameters. RESULTS: Overall, 77 (57%) patients had positive PD-L1 expression. Significantly high PD-L1 expression was observed in high-grade tumors (P = .006). We found that 37% of human papillomavirus (HPV)-associated subtypes and 73% of other histotype tumors expressed PD-L1, while 63% of HPV-associated tumors and 27% of other histotype tumors did not (odds ratio, 1.35; P = .002 when compared for HPV-associated groups vs all others). Similarly, PD-L1-positive tumors had a 3.61-times higher chance of being node positive than PD-L1-negative tumors (P = .0009). In addition, PD-L1 high-positive tumors had a 5-times higher chance of being p16ink4a negative than PD-L1 low-positive tumors (P = .004). The PD-L1-positive tumors had a lower overall survival and cancer-specific survival than PD-L1-negative tumors. CONCLUSIONS: Overall, PD-L1 expression is associated with high-grade and metastatic tumors. Lower PD-L1 expression is observed more frequently in HPV-associated (warty or basaloid) subtypes than in other, predominantly HPV-independent types. As a result, PD-L1 positivity, including higher expression, portends lower overall and cancer-specific survival. These data provide a rational for further investigating PD-L1-based immunotherapeutics in PC.

C11orf95-RELA, YAP1-MAMLD1, and YAP1-FAM118B Fusion Negative Anaplastic Ependymoma with Lipogenic Differentiation.

Lipogenic differentiation in ependymoma is an infrequent occurrence with very few reported cases. The grading was done solely based on the histomorphology and molecular subtyping was not described in such ependymomas. New molecular classification divided ependymomas in nine different subgroups, of which supratentorial location tumor usually exhibits C11orf95-RELA, YAP1-MAMLD1, and YAP1-FAM118B fusion proteins. A 46-year-old female presented with headache and right-sided parapresis. Radilogy revealed a large intraxial left parietooccipital mass lesion, which histologically and immuohistochemically confirmed as anaplastic ependymoma with extensive lipogenic changes. The ependymal origin of the tumor was corroborated by the immunohistochemistry and ultrastructural studies. Molecular studies for C11orf95-RELA, YAP1-MAMLD1, and YAP1-FAM118B fusion proteins were negative. This is the first documentation of fusion negative supratentorial anaplastic ependymoma with lipogenic differentiation. This novel finding needs further reinforcement by similar studies to identify its impact on the disease outcome.

Solitary Fibrous Tumor of the Kidney With Pure Round Cell Features: A Case Report With Review of Literature.

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm known to occur at various soft tissue and visceral locations. Kidney is a rarely reported site for these tumors. Most of the SFTs described in the kidney exhibit a classical CD34-positive patternless spindle cell histology. Focal round cell morphology is seldom reported. Herein, we describe a 48-year-old male patient with renal SFT. This tumor had pure round cell morphology with a CD34-/STAT6+ immunophenotype. Fluorescent in situ hybridization and a multiplexed sequencing assay performed on an Illumina® HiSeq 4000 platform revealed NAB2 and STAT6 gene rearrangement. Renal tumors with round cell morphology are diagnostically challenging and SFT is not often considered in the differential diagnosis of a round cell tumor of the kidney. Moreover, a CD34-negative profile can be rather confounding while diagnosing such lesions. In such scenarios, a strong nuclear STAT6 immunostaining is extremely helpful in clinching the diagnosis. SFT should always be considered in the differential diagnosis of round cell tumors of the kidney due to significant diagnostic and therapeutic implications.

Multifaceted Spindle Cell/Sclerosing Rhabdomyosarcoma With Role of Immunohistochemistry in Avoiding Misdiagnosis: A Multi-Institutional Study of 45 Distinct Tumors.

Background. Spindle cell/sclerosing rhabdomyosarcoma is a rare neoplasm and has an aggressive clinical course. Because of its rarity, we performed a multi-institutional collaboration to comprehend the overarching clinical, histopathological, and immunohistochemical characteristics of a cohort of spindle cell/sclerosing rhabdomyosarcoma. Materials and Methods. Forty-five patients with spindle cell/sclerosing rhabdomyosarcoma were identified. Demographics, clinical, histopathological, and immunohistochemistry data were reviewed and recorded. Results. The patients' age ranged from 1 to 85 years with a male to female ratio of 1.2:1. There were 15 children/adolescents and 30 adults. Eighteen (40%) tumors were located in the head and neck region. Twenty-four (53%) tumors displayed a bimorphic cellular arrangement with hypercellular areas having short, long, and sweeping fascicular and herringbone pattern, and hypocellular areas with stromal sclerosis and associated hyalinized and/or chondromyxoid matrix. Histomorphological differentials considered were leiomyosarcoma, malignant peripheral nerve sheath tumor, fibrosarcoma, nodular fasciitis, liposarcoma, synovial sarcoma, sarcomatoid carcinoma, solitary fibrous tumor, dermatofibrosarcoma protuberans, and schwannoma. Six tumors exhibited marked stromal sclerosis. The myogenic nature was confirmed by immunohistochemistry. Positivity for at least one skeletal muscle-associated marker (MyoD1 and/or myogenin) was observed. Conclusion. Spindle cell/sclerosing rhabdomyosarcoma diagnosis can be challenging as a number of malignant spindle cell neoplasm mimic this entity. Thus a correct diagnosis requires immunohistochemical work up with a broad panel of antibodies. In view of rarity of this neoplasm, further studies on a large cohort of patients with clinical follow-up data are needed for a better understanding of this tumor.

Diagnostic Utility of GATA3 and ISL1 in Differentiating Neuroblastoma From Other Pediatric Malignant Small Round Blue Cell Tumors.

Accurate diagnosis of neuroblastoma may be challenging, especially with limited or inadequate specimen and at the metastatic sites due to overlapping imaging, histopathologic, and immunohistochemical (immunohistochemistry [IHC]; infidelity among various lineage-associated transcription factors eg FLI1, transducin-like enhancer 1, etc) features. GATA3 and ISL1 have recently been described as markers of neuroblastic differentiation. This study aims at determining the diagnostic utility of GATA3 and ISL1 in differentiating neuroblastoma from other pediatric malignant small round blue cell tumors.We evaluated GATA3 and ISL1 expression in 74 pediatric small round blue cell tumors that included 23 NMYC-amplified neuroblastomas, 11 EWSR1-rearranged round cell sarcomas, 7 SYT::SSX1-rearranged synovial sarcomas, 5 embryonal rhabdomyosarcomas, 10 Wilms tumors (nephroblastomas), 7 lymphoblastic lymphoma, 7 medulloblastoma, and 4 desmoplastic small round cell tumor.All 23 neuroblastomas (moderate to strong staining in >50% of the tumor cells), 5 T-lymphoblastic lymphomas (moderate to strong staining in 40%-90% of the tumor cells), and 2 desmoplastic small round cell tumors (weak to moderate staining in 20%-30% of the tumor cells) expressed GATA3, while other tumors were negative. ISL1 immunoreactivity was observed in 22 (96%) neuroblastomas (strong staining in in >50% of the tumor cells, n = 17; moderate to strong staining in 26%-50% of the tumor cells, n = 5), 3 embryonal rhabdomyosarcoma (moderate to strong staining in 30%-85% of the tumor cells), 1 synovial sarcoma (weak staining in 20% of the tumor cells), and 7 medulloblastoma (strong staining in 60%-90% of the tumor cells). Other tumors were negative. Overall, GATA3 showed 86% specificity, 100% sensitivity, and 90% accuracy for neuroblastoma, with a positive predictive value (PPV) and negative predictive value (NPV) of 77% and 100%, respectively. ISLI showed 72% specificity, 96% sensitivity, and 81% accuracy for neuroblastoma, with a PPV and NPV of 67% and 97%, respectively. After the exclusion of T-lymphoblastic lymphoma and desmoplastic small round cell tumors, GATA3 had 100% specificity, sensitivity, accuracy, and PPV and NPV for neuroblastoma. Similarly, in pediatric small round blue cell tumors, ISL1 had 100% specificity, sensitivity, accuracy, PPV, and NPV for neuroblastoma, after embryonal rhabdomyosarcoma, synovial sarcoma, and medulloblastoma were excluded. CONCLUSIONS: GATA3 and ISL1 may be valuable in the diagnostic work-up of neuroblastoma and may reliably be used to support the neuroblastic lineage of pediatric small round blue cell tumors. Furthermore, dual positivity helps in challenging scenarios, when there is equivocal imaging, overlapping IHC features, limited specimen, and the lack of facility for a molecular work up.

SS18-SSX Expression in a Contemporary Cohort of Primary Renal Synovial Sarcoma: A Multi-Institutional Experience of Fourteen Patients.

Primary renal synovial sarcoma is a rare aggressive mesenchymal neoplasm of the kidney that accounts for less than 1% of renal sarcomas. Herein, we describe the clinicopathologic and molecular findings of 14 renal synovial sarcoma patients in one of the largest case series to date and to our knowledge, the only renal synovial sarcoma series to use novel SS18-SSX IHC. Clinicopathologic, IHC, molecular, management, and follow-up data were reviewed and analyzed. Macroscopically, the tumors had either homogeneous, tan-white, and solid (n = 10), variegated and solid (n = 3), or variegated and solid-cystic (n = 1) cut surfaces. Spindle cell (n = 10), round cell (n = 3), and round to epithelioid morphologies (n = 1) were observed. SS18-SSX IHC was positive in all 14 tumors (diffuse, n = 10; multifocal, n = 2; focal, n = 2). All the tumors harbored SS18::SSX1/2 gene rearrangement. Metastases to the liver, brain, and lung (n = 1); liver and bone (n = 1); liver and diaphragm (n = 1) were identified. Adjuvant chemotherapy was administered in 11/12 patients. Follow-up was available for 10 patients (time period range: 5 to 24 months). Four patients died of disease, and six patients are alive with no recurrence or metastasis. As SS18-SSX IHC showed an excellent concordance with the FISH results, this may reliably be used in the IHC panel of spindle/round cell sarcomas of the kidney and as a molecular surrogate for renal synovial sarcoma, particularly in a resource-limited setting. Also, the tumors with focal SS18-SSX expression had lower break apart signals in the FISH assay (19% and 23% in two tumors with focal SS18-SSX IHC positivity).

Meningeal Rosai-Dorfman Disease Presenting as an Intracranial Mass - Report of a Case with Review of the Literature.

Meningeal Rosai-Dorfman disease, a type of sporadic Rosai-Dorfman disease, is a rare occurrence. A few cases are reported in the English literature with an adequate immunohistochemical workup. This entity clinically and radiologically mimics either a meningeal or a parenchymal neoplasm with meningeal extension, warranting a thorough histopathologic evaluation. A broad histologic differential necessitates a detailed immunohistochemical characterization to render a correct diagnosis that has significant therapeutic and prognostic implications. Herein, we report a case of isolated meningeal Rosai-Dorfman disease in a 50-years-old human immunodeficiency virus-positive male patient with an emphasis on the histopathology, immunoprofile, and differential diagnoses.

Reporting Trends, Practices, and Resource Utilization in Neuroendocrine Tumors of the Prostate Gland: A Survey among Thirty-Nine Genitourinary Pathologists.

Background. Neuroendocrine differentiation in the prostate gland ranges from clinically insignificant neuroendocrine differentiation detected with markers in an otherwise conventional prostatic adenocarcinoma to a lethal high-grade small/large cell neuroendocrine carcinoma. The concept of neuroendocrine differentiation in prostatic adenocarcinoma has gained considerable importance due to its prognostic and therapeutic ramifications and pathologists play a pivotal role in its recognition. However, its awareness, reporting, and resource utilization practice patterns among pathologists are largely unknown. Methods. Representative examples of different spectrums of neuroendocrine differentiation along with a detailed questionnaire were shared among 39 urologic pathologists using the survey monkey software. Participants were specifically questioned about the use and awareness of the 2016 WHO classification of neuroendocrine tumors of the prostate, understanding of the clinical significance of each entity, and use of different immunohistochemical (IHC) markers. De-identified respondent data were analyzed. Results. A vast majority (90%) of the participants utilize IHC markers to confirm the diagnosis of small cell neuroendocrine carcinoma. A majority (87%) of the respondents were in agreement regarding the utilization of type of IHC markers for small cell neuroendocrine carcinoma for which 85% of the pathologists agreed that determination of the site of origin of a high-grade neuroendocrine carcinoma is not critical, as these are treated similarly. In the setting of mixed carcinomas, 62% of respondents indicated that they provide quantification and grading of the acinar component. There were varied responses regarding the prognostic implication of focal neuroendocrine cells in an otherwise conventional acinar adenocarcinoma and for Paneth cell-like differentiation. The classification of large cell neuroendocrine carcinoma was highly varied, with only 38% agreement in the illustrated case. Finally, despite the recommendation not to perform neuroendocrine markers in the absence of morphologic evidence of neuroendocrine differentiation, 62% would routinely utilize IHC in the work-up of a Gleason score 5 + 5 = 10 acinar adenocarcinoma and its differentiation from high-grade neuroendocrine carcinoma. Conclusion. There is a disparity in the practice utilization patterns among the urologic pathologists with regard to diagnosing high-grade neuroendocrine carcinoma and in understanding the clinical significance of focal neuroendocrine cells in an otherwise conventional acinar adenocarcinoma and Paneth cell-like neuroendocrine differentiation. There seems to have a trend towards overutilization of IHC to determine neuroendocrine differentiation in the absence of neuroendocrine features on morphology. The survey results suggest a need for further refinement and development of standardized guidelines for the classification and reporting of neuroendocrine differentiation in the prostate gland.

Low-grade oncocytic tumour of the kidney is characterised by genetic alterations of TSC1, TSC2, MTOR or PIK3CA and consistent GATA3 positivity.

Low-grade oncocytic tumour (LOT) of the kidney has recently emerged as a potential novel tumour type. Despite similarity to oncocytoma or eosinophilic chromophobe renal cell carcinoma, it shows diffuse keratin 7 immunohistochemistry (IHC) and negative KIT (CD117), which differs from both. We aimed to identify the molecular characteristics of these tumours. Seventeen tumours (one male, 16 female, nine previously published) fitting the original description of this entity (solid eosinophilic cell morphology, often with areas of tumour cells loosely stretched in oedematous stroma, and the above IHC features) were analysed with a next-generation sequencing panel of 324 cancer-associated genes from formalin-fixed, paraffin-embedded tissue. All tumours harboured at least one alteration in either TSC1 (n = 7, 41%), TSC2 (n = 2, 12%), MTOR (n = 5, 29%) or PIK3CA (n = 4, 24%). Four tumours harboured a second alteration, including two NF2, one each in conjunction with MTOR and TSC2 alterations, one PTEN with TSC1 alteration and one tumour with both MTOR and TSC1 alterations. No other renal cancer-related or recurring gene alterations were identified. In addition to the previously described IHC findings, 16 of 16 were positive for GATA3. Eleven patients with follow-up had no metastases or recurrent tumours. Recurrent tuberous sclerosis/MTOR pathway gene alterations in LOT support its consideration as a distinct morphological, immunohistochemical and genetic entity. PIK3CA is another pathway member that may be altered in these tumours. Further study will be necessary to determine whether tumour behaviour or syndromic associations differ from those of oncocytoma and chromophobe carcinoma, warranting different clinical consideration.

Solitary Fibrous Tumor of the Adrenal Gland.

OBJECTIVES: Solitary fibrous tumor (SFT) is a mesenchymal neoplasm that can arise at various anatomic locations. It is characterized by inv12(q13q13)-derived NAB2::STAT6 fusion, resulting in the nuclear expression of STAT6. Primary SFT of the adrenal gland is rare. We launched a multi-institutional collaboration to comprehend the overarching demographics, clinical and follow-up, macroscopic, microscopic, IHC, and FISH features of 9 patients with SFT of the adrenal gland. METHODS: We added a series of 9 patients to the collection of adrenal SFTs where the clinicopathologic parameters, including clinical presentation, imaging, histopathology, IHC, molecular profiles, and management and follow-up data, were analyzed comprehensively. A modified 4-variable risk stratification model, including age, tumor size, and necrosis, was applied. RESULTS: Our series consisted of 6 male and 3 female patients, ranging in age from 19 to 64 years (mean, 49.3 years). Abdominal pain (4) and fever with abdominal pain (1) were the presenting symptoms in 5 patients. In the remaining 4 patients, the tumors were detected by abdominal imaging for hypertension and diabetes. The size of the tumor ranged from 2 cm to 10.5 cm in maximum dimension. All tumors exhibited the morphology of a spindle cell SFT with a patternless architecture; 3 had a focal storiform arrangement. STAT6 positivity was observed in all tumors, and 7 were positive for CD34. Surgical resection was the primary modality of treatment. No adjuvant therapy was administered. Follow-up ranging from 7 months to 23 months was available for 7 patients. All were alive without disease recurrence or metastasis. Risk stratification placed 8 (88.9%) patients into a low-risk category and 1 into an intermediate-risk category. CONCLUSIONS: This series is the largest of adrenal SFTs to date. These tumors of the adrenal gland are predominantly spindle cell neoplasms with indolent behavior, with a wide age distribution and a slight male preponderance. Combining our cohort with the previously published cases, the majority of tumors fall into the low-risk category for the propensity to develop metastases. Owing to the rarity and age distribution associated with these tumors, the differential diagnosis is wide and requires a systematic approach for ruling out key differential diagnoses aided by STAT6 IHC.

Application of the Indian Academy of Cytologists Recommendations for Reporting Serous Fluid Cytopathology in Routine Reporting of Ascitic Fluid Specimen and Assessment of the Risk of Malignancy.

Background: A five-tiered reporting system for effusion fluid cytology has been published by the Indian Academy of Cytologists (IAC). Only a single study has evaluated the applicability of this system in routine reporting. Aims: We intend to evaluate the practical utility of this system in routine reporting of ascitic fluid cytology. Materials And Methods: Nine hundred and sixty-one cases of ascitic fluid cytology were included in this study. The clinical, radiological, cytomorphological, and follow-up data of these cases were reviewed. All cases were recategorized according to the proposed IAC system, and the risk of malignancy (ROM) for each category was estimated. Results: Age of the patients ranged from 1 to 92 years, and fluid volume ranged from 10 ml to 3 l. The number of cases included in each category and their respective ROM were as follows: category 1: 41, 21.42%; category 2: 805, 14.9%; category 3: 5, 33.3%; category 4: 31, 90%; and category 5:79, 96.4%. Conclusions: The new IAC guidelines for the serous fluid is representative, informative, and could be easily applied at our institutional level. We used the recommended diagnostic categories for reclassifying the ascitic fluid samples based on their cytosmear findings and conclude that the system has enormous utility at each level starting from the collection of fluid samples till the delivery of the report.

Adequacy in pleural effusion: What is the minimum volume required for detection of malignant cells?

BACKGROUND: Adequacy criteria of pleural fluid volume for optimal reporting are contentious, and very little literature is available to date. This problem has not been addressed in the novel International System for Reporting Serous Fluid Cytology. MATERIALS AND METHODS: A retrospective analysis was performed on 939 pleural fluid samples. Five volume bins were created: 0-9.9 ml, 10-19.9 ml, 20-34.9 ml, 35-69.9 ml, and > 70 ml and included 203, 222, 314, 174, and 26 samples, respectively. Volume bins were compared across various categories using a Chi-square test. A malignancy fraction was used to assess diagnostic accuracy. Descriptive statistics for categorical variables were done with median and interquartile range. A ROC curve was constructed to find if pleural fluid volume can be used to detect malignancy. A cut-off volume was found which can detect malignancy with optimum sensitivity. RESULTS: The area under the Receiver Operating Characteristic curve showed that 55% of the time, the pleural volume can detect malignancy correctly. From the coordinates of the curve it was found that for a sensitivity of 81% and specificity of 40%, a cut-off volume of 13.5 ml of pleural fluid is sufficient to detect malignancy. CONCLUSIONS: We recommend 13.5 ml as the minimum volume cut-off for a satisfactory pleural effusion cytology report. Below this volume, the false-negative rates increase, and the specimen may be deemed as limited for a conclusive diagnosis. As the volume rises above this threshold volume, the false negativity rate decreases but does not significantly improve malignant cells' detection.

Does Immunohistochemistry Add to Morphology in Differentiating Trichoepithelioma, Desmoplastic Trichoepithelioma, Morpheaform Basal Cell Carcinoma, and Microcystic Adnexal Carcinoma?

BACKGROUND: The distinction among cutaneous basaloid neoplasms such as trichoepithelioma (TE), desmoplastic trichoepithelioma (DTE), morpheaform basal cell carcinoma (MBCC), and microcystic adnexal carcinoma (MAC) can be difficult, especially in superficial biopsies. As the treatment plan of each entity is different, accurate characterization is important for appropriate management. While TE and DTE are benign neoplasms with indolent behavior, MBCC and MAC are typically locally aggressive. The expression of several recently described immunohistochemical (IHC) markers, including p40, IMP3, and ProEx C, has not been adequately established in cutaneous neoplasms. We explored the potential utility of a broad IHC panel, including previously reported and novel markers to differentiate TE, DTE, MBCC, and MAC. DESIGN: A total of 35 archival cases [TE (n=14), DTE (n=9), MBCC (n=6), and MAC (n=6)] were stained with 9 IHC markers: p40, IMP3, ProEx C, p16, CK20, Ki-67, androgen receptor, D2-40, and beta-catenin. Tumors with >5% immunoreactivity were scored as positive. The intensity was scored on a scale from 1+ to 3+. The pattern of positivity- nuclear, cytoplasmic, membranous, or in combination; peripheral or central distribution with lesion was also recorded. RESULTS: CK20 (in contrast to prior studies) and IMP3 were negative in all cases. Likewise, with the exception of one case of TE, androgen receptor showed no immunoreactivity in all categories. No significant difference was observed in the expression of beta-catenin, p16, ProEx C, and p40 among the four groups of cutaneous neoplasms. The mean Ki-67 labeling index for MBCC (8%) was slightly higher than DTE (3%). Interestingly, the proliferation index for TE (15%) was significantly higher than that of MBCC. All six cases of MAC and 36% of TEs expressed D2-40; neither the MBCC nor DE cases showed D2-40immunoreactivity. Also, we confirmed the previously published observation of scattered CK20 positive Merkel cells in the epidermis of all cases of DTE; whereas, no Merkel cells were identified in MBCC and MAC cases. CONCLUSIONS: Except Ki-67, our IHC panel showed no significant added diagnostic utility of IHC in discriminating among TE, DTE, MBCC, and MAC. Among the four cutaneous neoplasms, DTE and MBCC show a small but discernible difference in Ki-67.

Correlation of ROS1 (D4D6) Immunohistochemistry with ROS1 Fluorescence In Situ Hybridization Assay in a Contemporary Cohort of Pulmonary Adenocarcinomas.

Sambit K. MohantyObjective Repressor of Silencing ( ROS1 ) gene rearrangement in the lung adenocarcinomas is one of the targetable mutually exclusive genomic alteration. Fluorescence in situ hybridization (FISH), immunohistochemistry (IHC), next-generation sequencing, and reverse transcriptase polymerase chain reaction assays are generally used to detect ROS1 gene alterations. We evaluated the correlation between ROS1 IHC and FISH analysis considering FISH as the gold standard method to determine the utility of IHC as a screening method for lung adenocarcinoma. Materials and Methods A total of 374 advanced pulmonary adenocarcinoma patients were analyzed for ROS1 IHC on Ventana Benchmark XT platform using D4D6 rabbit monoclonal antibody. FISH assay was performed in parallel in all these cases using the Vysis ROS1 Break Apart FISH probe. Statistical Analysis The sensitivity, specificity, positive and negative likelihood ratios, positive and negative predictive values, and accuracy were evaluated. Results A total of 17 tumors were positive either by IHC or FISH analysis or both (true positive). Four tumors were positive by IHC (H-score range: 120-270), while negative on FISH analysis (false positive by IHC). One tumor was IHC negative, but positive by FISH analysis (false negative). The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, positive predictive value, negative predictive value, and accuracy were 94.4% (confidence interval [CI]: 72.71-99.86%), 63.6% (CI: 30.79-89.07%), 2.6 (CI: 1.18-5.72), 0.09 (CI: 0.01-0.62), 80.95% (CI: 65.86-90.35%), 87.5% (CI: 49.74-98.02%), and 82.76%, respectively. Conclusion ROS1 IHC has high sensitivity at a cost of lower specificity for the detection of ROS1 gene rearrangement. All IHC positive cases should undergo a confirmatory FISH test as this testing algorithm stands as a reliable and economic tool to screen ROS1 rearrangement in lung adenocarcinomas.

Choroid Plexus Carcinoma with Hyaline Globules: An Uncommon Histological Finding.

Background: Choroid plexus carcinoma (CPC) is a predominately pediatric CNS tumor with a variety of histologic features, with hyaline globules only reported once previously. Case report: A two-year-old male child presented with headaches, vomiting, and lower limb weakness. Radiological examination revealed a right temporoparietal intra-axial tumor. On histology, it showed features of CPC containing multiple eosinophilic intracytoplasmic and extracellular hyaline globular structures, which were PAS-positive, diastase resistant, and immunoreactive for alpha-fetoprotein (AFP). Conclusion: CPC can occasionally show AFP immune-positive hyaline globules.

Squamous Metaplasia in a Borderline Phyllodes Tumor-an Undocumented Histological Finding in Male Breast: Report of a Case and Review of Literature.

Phyllodes tumor is a paradigm of fibroepithelial neoplasm that accounts for <1% of the breast neoplastic lesions usually detected in females and uncommonly in the male breast. The World Health Organization classifies the tumor into benign, borderline, and malignant based on the predefined morphological criteria. Squamous differentiation in phyllodes tumor is epithelial metaplasia, which has been occasionally documented in English literature. We report the first undocumented case of a recurrent borderline phyllodes tumor with cystic squamous metaplastic change in a 32-year-old male patient. The histology was that of a fibroepithelial neoplasm with the typical leaf-like projections and cystic spaces lined by squamous epithelium containing keratin debris. The purpose of presenting this case is to elucidate the pathogenesis and discuss other malignant and benign breast lesions that may be included in the differential diagnosis when evaluating a breast lesion with squamous metaplasia, particularly in the context of fine-needle aspirates.

Cytomorphological features of Mammary Analog secretory carcinoma of parotid gland: Report of 3 cases and review of literature.

Mammary analog secretory carcinoma (MASC) of salivary gland is a recently described entity. Due to its rarity and cytomorphological overlap with other salivary gland tumors, it is often difficult to recognize on cytology. Here we describe three such cases with their histopathological correlation. All the three tumors arose in the parotid gland. They were misdiagnosed as mucoepidermoid carcinoma, acinic cell carcinoma and salivary duct adenocarcinoma, respectively. Final diagnosis of MASC was established on their follow-up histopathology and immunochemistry evaluation. Cytosmears of these tumors showed high cellularity with papillary architecture lying within fluid background rich in foamy macrophages. Nuclear atypia varied from minimal to marked with frequent mitosis and presence of necrosis. Cytoplasmic vacuolation was a consistent finding. Although the cytomorphological features of MASC are not specific, a diagnosis of MASC should be strongly considered in the presence of papillary architecture, prominent cytoplasmic vacuolations of the tumor cells and a background of cyst fluid. Immunohistochemistry on cell block may be done to confirm the diagnosis.

Application of the International System for Reporting Serous Fluid Cytopathology in routine reporting of pleural effusion and assessment of the risk of malignancy.

INTRODUCTION: The International System for Reporting Serous Fluid Cytopathology (ISRSFC) was proposed by the International Academy of Cytology and the American Society of Cytopathology. AIM OF THE STUDY: We have applied this system for reporting of pleural effusion cytology and report our experience. MATERIALS AND METHODS: All the pleural effusions from January 2019 to June 2020 were retrieved from the database. All these cases were reviewed and recategorized according to the proposed system of 5 categories: non-diagnostic (ND), negative for malignancy (NFM), atypia of uncertain significance (AUS), suspicious for malignancy (SFM), and malignant (MAL). The risk of malignancy (ROM) for each category was evaluated. RESULTS: A total of 939 cases were studied. The age of patients ranged from 2 to 88 years, and the volume of fluid ranged from 1 to 600 ml. There were 41 ND (4.37%), 697 NFM (74.23%), 44 AUS (4.69%), 27 SFM (2.88%), and 130 MAL (13.84%) cases. The ROM for the categories were found to be 87.5%, 51.61%, 88.23%, 87.5%, and 100% respectively. CONCLUSIONS: The ISRSFC is a user-friendly system for use in reporting of pleural fluid. The criteria for defining the various categories need to be further elaborative and stricter for this system to be more effective. More studies are required for the estimation of the ROM for each category.

Krukenberg Tumor of Ovary During Pregnancy: Learning From A Mistake.

Sertoli-Leydig cell tumor of the ovary with heterologous differentiation is a relatively uncommon tumor that occurs in females of variable age range. Krukenberg tumor (KT) is a relatively more common tumor of the ovary although only a few cases of KT occur during pregnancy making it an equally uncommon tumor in this setting. We received a unilateral ovarian mass in a 25-yr-old primigravida which we reported as Sertoli-Leydig cell tumor with heterologous (intestinal) differentiation based on its clinical and histomorphologic features. However, on further investigation, a gastric mass was found which was a signet-ring cell adenocarcinoma. We rectified our diagnosis of ovarian mass as KT. We retrospectively analyzed the reasons for our mistake and concluded that the rarity coupled with the nonclassic clinical features and histomorphology of KT during pregnancy pose challenges to the correct diagnosis. This report highlights the diagnostic challenges faced by us along with the ways to circumvent them in the future.