Fumarate hydratase-deficient renal cell carcinoma: an oncology care institutional experience.

Renal cell carcinoma (RCC) accounts for 2% of all cancer cases worldwide, and majority are sporadic. The latest World Health Organization (WHO) classification of renal cell tumors (fifth edition, 2022) has molecularly defined renal tumor entities, which includes fumarate hydratase (FH)-deficient RCC. FH-deficient RCC is an aggressive carcinoma caused by pathogenic alterations in FH gene, seen in 15% of patients with hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) syndrome. These tumors occur more frequently at a younger age and present at an advanced stage, carrying a dismal prognosis. We report a series of 10 cases of FH-deficient RCC. The mean age was 49.8 years, and all cases presented in advanced stages (III and IV). Morphologically, the cases had varied architectural patterns with characteristic eosinophilic macronucleoli and perinucleolar halo. On immunohistochemistry (IHC), all showed diffuse nucleo-cytoplasmic expression of S-(2-succino)-cysteine (2-SC), with loss of FH in seven cases. FH-deficient RCCs are aggressive neoplasms and can be diagnosed using specific IHC markers (FH and 2-SC). These patients should undergo germline testing for FH gene mutation, genetic counseling, and surveillance of family members.

Amendments in surgical pathology reports: An 8-year institutional experience.

Surgical pathology reports may undergo revisions broadly categorized as addenda (supplementary information) or amendments (changes to finalized reports). Amendments indicate potential flaws in the diagnostic process and serve as important indicators of vulnerabilities in the histopathology workflow. This study analyzed the frequency and distribution of amendments in surgical pathology reports over 8 years to identify patterns highlighting opportunities for improvement. Surgical biopsies, excisions, and resections were included; cytology and molecular tests were excluded. Amended reports were categorized using previously used taxonomy documented in literature. Defects were classified as misinterpretations, misidentifications, defective specimens, or defective reports. Of 101,355 reports, 155 (0.15 %) were signed out with amendments. The amendment rate was approximately 1-2 cases per 1000 reports annually. Misinterpretations accounted for the majority (52 %) of amended reports, with undercalls (62 %) and overcalls (27 %) being predominant subtypes. Tumor staging was amended in 57 (37 %) cases, with 30 being upstaged and 11 downstaged clinically. The highest number of misinterpretation defects occurred in head and neck (36 %) and breast (21 %) specimens. Misinterpretation defects were present in 53 % of malignant cases versus 42 % of benign cases. In 18 cases, there were significant changes in pathological diagnosis (14 major and 4 minor). A standard taxonomy categorizing report defects is crucial for measuring and improving quality control. Accurate pathology reporting impacts patient care and guides workflow improvements. This taxonomy enables us to track variations and deficiencies in our pathology reporting processes in a reproducible way across the department.

Extranodal follicular dendritic cell sarcoma presenting as colonic mass: A diagnostic and therapeutic challenge.

Folliclular dendritic cell sarcoma (FDCS) is an extremely rare neoplasm originating from folliclular dendritic cells, both nodally and extranodally. Its primary presentation as a large colonic mass is rare and can be misdiagnosed as epithelial tumor/soft tissue tumor both clinically and through histomorphology. Due to its rarity and limited consensus guidelines about its management, it presents as a diagnostic and therapeutic challenge for pathologists and oncologists. However, accurate diagnosis is imperative due to its distinct prognostic and therapeutic implications. Herein we report, two cases of extranodal FDCS of colon with the aim of contributing to the management of this uncommon entity.

Diagnostic utility of LMO2 immunohistochemistry in distinguishing T-lymphoblastic leukemia/lymphoma from thymoma.

Distinguishing T-lymphoblastic leukemia/lymphoma (T-ALL/T-LBL) from thymomas (especially B1 or B2 type) can be challenging particularly in limited trucut biopsy material where appreciating architecture is difficult or the background epithelial component does not provide tangible evidence for definite diagnosis. As a pathologist, it is important to accurately diagnose these neoplasms because they have entirely distinct management protocols. Recent studies have reported that LIM Domain Only 2 (LMO2) is expressed in neoplastic lymphoblasts of T-ALL/T-LBL and is absent in thymocytes of normal thymuses or thymomas. An observational study was done to test the sensitivity and specificity of LMO2 in differentiating neoplastic lymphoblasts from thymocytes of thymomas/normal thymuses. Our study showed that LMO2 had sensitivity of 70% and specificity of 100% in diagnosing LBL. None of the thymomas (B1 or B2 type) showed expression of LMO2 in the neoplastic cells. LMO2 is a reliable marker of transformed T-cell precursors and should be routinely included in immunohistochemical panel when evaluating thymic/mediastinal neoplasms.

Primary orbital yolk sac tumor in an infant: A rare entity.

We report a case of pure orbital yolk sac tumor (YST) in an 11-month-old infant, which is a rare entity. The child presented with progressive painless swelling of the right eye and on examination had proptosis, chemosis, and lid edema. Systemic examination was within normal limits. Magnetic resonance imaging (MRI) orbit revealed a lobulated heterogeneously enhancing right retroocular mass extending up to the orbital apex, displacing the optic nerve and eroding the medial orbital wall. Biopsy of the lesion revealed pure YST histology. Serum alpha-fetoprotein (AFP) was markedly raised at 76900 ng/mL. She was started on infant bleomycin etoposide cisplatin (BEP) chemotherapy protocol. There was a good clinical and radiological response. A high index of malignancy is required in young children presenting with orbital proptosis. A multidisciplinary approach and early intervention are essential to save both vision and life.

Primary pulmonary NUT midline carcinoma: An elusive and a rare diagnostic entity.

Nuclear protein in testis (NUT) midline carcinoma is a poorly differentiated tumor, is more common in midline anatomic sites, and involves young adults and children mainly. Primary pulmonary NUT midline carcinoma (NMC) is a rare and poorly defined entity in the prevailing literature. Being a highly aggressive and fatal neoplasm, it gets incumbent for the oncologists and the pathologists to be aware of this entity as it holds distinct management protocol and prognosis. Currently, BET inhibitors (BETi) and histone deactylase inhibitors have shown promising results as targeted therapies in clinical trials in head and neck NMC. We present a case report of NMC of primary pulmonary location in a young male with widespread bony metastasis.

Correlation NKX2.2 IHC and EWSR1 break-apart FISH in the diagnosis of Ewing sarcoma: Can combined NKX2.2 and CD99 immunoexpression obviate or minimize the need of FISH testing? First assessment study from Indian tertiary cancer care center.

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.

PD-L1 expression in muscle invasive urothelial carcinoma: Comparison of SP142 and SP263 assay.

Introduction: High-grade urothelial carcinoma has a different molecular pathway than superficial low grade urothelial carcinoma, and is characterized by genomic instability. The high tumor mutation burden leads to neoantigen formation, evoking an immune response. The immune response has been keenly studied in last two decades and programmed death ligand-1 (PDL-1) has emerged as acceptable immunohistochemical marker for assessment of response to therapy, prognostication and patient selection for immunotherapy. The targeting of PD-1 and PDL-1 by checkpoint inhibitors (CPIs) is an attractive strategy to unblock the inhibitor and induce cytotoxic cell death. However, the presence of complementary and companion diagnostic testing with multiple PDL-1 assays and platforms for various CPIs make a diagnostic quagmire. Thus, it is the need of hour to harmonize these assays. In this undertaken study we evaluated the concordance in PD-L1 expression between the two PD-L1 clones: SP263 and SP142, in treatment naïve muscle invasive bladder cancer (MIBC). Methods: We evaluated Ventana PD-L1 "SP263 and SP142" qualitative immunohistochemical assay using rabbit monoclonal anti-PD-L1 clones in evaluation of PDL-1 immunoexpression on Ventana autostainer platform. The study includes 30 muscle invasive urothelial carcinomas, with 10 of 30 having nodal metastasis. Results: SP263 assay was statistically more sensitive than SP142 for tumor cell (TC) scoring (P = 0.0009), whereas SP142 was more sensitive for immune cell (IC) scoring (P = 0.0067). There was no statistical significant discordance for TC or IC scoring between primary tumor and metastatic lymph node. Conclusion: PD-L1 testing status can be done on both primary tumor and metastatic site, however in metachronous metastatic setting, testing on recent metastatic site should be preferred. The harmonization of immunoexpression between 2 PD-L1 clones could not be achieved.

Molecular stratification of high-grade urothelial carcinoma by immunohistochemistry with its histomorphological and clinical correlation.

Introduction: Urothelial carcinoma poses a significant cause of morbidity and mortality. The recent classification of Tumors of Urinary System by World Health Organization fourth edition) has elucidated its molecular subtypes and its associated prognostic significance. Methods: We used immunohistochemistry marker expression (CK5/6, CK20, CD44, EGFR) as a surrogate marker, to stratify 150 cases of high-grade urothelial carcinoma into the intrinsic molecular subtypes. A correlation was also done with immunohistochemical markers p53, p21, E-cadherin and Ki-67. Results: On subtyping, 47.3% cases were basal, 42.7% luminal and 10% remained unclassified. We did not find GATA3 useful for molecular stratification in our study. Muscle invasion was seen in 59% of basal and 31% of luminal subtype (P = 0.016). Squamous differentiation was most commonly associated with basal subtype (P < 0.001). EGFR expression was seen in 62% of basal and 38% of luminal subtype (P = 0.014), and thus can be used as an additional marker for molecular stratification. Overexpression of p53 was seen in 64% cases of muscle invasive and 36% of non-muscle invasive high-grade carcinomas (P < 0.0001). An inverse relationship was observed between p53 and p21 immunoexpression (r = -0.494) (P < .0001). The overall survival at 1- and 2-year interval was more in the luminal subtype, suggesting an early mortality in basal group, (P = 0.827), and at 6 years both the groups had almost similar results. Conclusion: High-grade urothelial carcinoma is challenging in terms of therapeutic strategy. Increased understanding of underlying molecular basis helps identifying targetable treatment options, and newer biomarkers will enhance predictive and prognostic stratification.

Angiomatoid fibrous histiocytoma: Report of two cases, initially construed as sarcoma with unusual clinico-pathological features.

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor of uncertain differentiation with low metastatic potential, most commonly occurring in children, adolescents, and young adults, involving extremities. Due to its rare nature and diverse presentation, both clinically and morphologically, it is often misdiagnosed. It becomes important to correctly diagnose this lesion, given its distinct therapeutic implications. Here, we present the clinical, radiologic, and pathologic findings of two rare cases of AFH. Since AFH is a rare soft tissue tumor with low malignant potential, both pathologists and clinicians should be aware of this entity, when encountered with a soft tissue mass in extremities of a child or adolescent, so as to accord appropriate treatment in such cases.

Multifocal primary pseudomyogenic hemangioendothelioma of bone managed with denosumab: A rare case with diagnostic and therapeutic challenge.

Pseudomyogenic hemangioendothelioma (PMH) is a rare tumor of vascular origin with intermediate malignant potential which commonly presents as a subcutaneous and soft-tissue mass with or without concurrent bone involvement. However, PMH presenting as primary multifocal bone lesions is rare. Histomorphologically, it mimicks other epithelioid tumors and cytokeratin expression in PMH can prompt an erroneous diagnosis of metastatic carcinoma, especially in an elderly patient. Diligent histopathological examination and judicious immunohistochemistry panel can guide to the correct diagnosis. Due to its rarity, the optimal therapeutic strategy has not been established till date. We present a rare case of PMH of primary bone with multifocal bony disease in a 23-year-old male who presented with severe bone pains. The patient has been managed with four weekly denosumab, and the disease is stable with symptomatic relief after 6 months.

Intrathyroidal Plasmacytoma with Pleomorphic Multilobated Bizarre Cells: A Rare Primary Clinicopathological Presentation Mimicking Anaplastic Carcinoma of Thyroid.

BACKGROUND: Plasmacytoma involving thyroid gland is infrequent and can present as either primary extramedullary plasmacytoma or secondary to multiple myeloma. METHODS AND RESULTS: We present a case of 71 years old male who complained of a huge anterior neck swelling accompanied by dysphagia and dyspnoea. Fine needle aspiration cytology was suggestive of anaplastic carcinoma of thyroid (ATC), however, the subsequent histomorphology supported by immunohistochemistry (IHC) astoundingly favoured the diagnosis of plasmacytoma. Further evaluation revealed the presence of lymphadenopathy and single bone lesion in the present case which was rather suggestive of secondary involvement of thyroid to multiple myeloma. However, the case was unique in view of its presentation as a rapidly enlarging thyroid mass associated with stridor and cytomorphological findings which were of an undifferentiated malignancy favouring ATC. The use of a broad and judicious IHC panel clinched the final diagnosis of plasmacytoma. CONCLUSION: The present case emphasizes the diligent use of IHC in such cases given different therapeutic and prognostic implications.

Epithelioid haemangioma of bone: A series of four cases with a revision of this contentious entity.

Epithelioid hemangioma of bone is a rare and locally aggressive vascular neoplasm of bone associated with a good prognosis. Because of its worrisome histomorphologic features and aggressive clinicoradiologic findings, at times with multifocal presentation, they tend to simulate malignant tumors. We report a series of four cases of epithelioid hemangioma of bone with their clinicopathologic characteristics. All had adjacent soft tissue involvement and two had multifocal bone disease. Microscopically, all cases had a tumor in lobular configuration, composed of epithelioid endothelial cells with the formation of well-formed vessels or grew in solid sheets. The tumor cells lacked significant cytologic atypia, necrosis, and increased mitosis. All cases were immunohistochemically positive for vascular markers CD34, CD31, ERG1, whereas negative for CK. Two of the cases were treated with excision, and the other two underwent curettage. None had local recurrence or metastasis on follow-up. This study highlights the importance of recognizing histomorphological and clinicoradiological features for distinguishing epithelioid hemangiomas from malignant vascular neoplasms of bone because of their distinct therapeutic implications and clinical outcomes.

Cytomorphological Categorization of Thyroid Lesions according to The Bethesda System for Reporting Thyroid Cytology and Correlation with their Histological Outcome: An Indian Oncology Centre Experience.

Objective: The objective of this study was to report the experience of an Indian premiere tertiary care oncology center in reporting fine needle aspiration cytology of thyroid lesions according to the Bethesda system of reporting thyroid cytopathology (TBSRTC) given by National Cancer Institute (NCI). These were then correlated with their histopathological outcome, analyzing the level of specificity and sensitivity of the procedure. Material and Methods: Aspiration cytology of thyroid lesions, presented during a 5.5-year duration, was reported retrospectively and prospectively, according TBSRTC, and correlated with their histopathologic diagnosis. Results: A total of 431 patients were evaluated comprising 289 females and 142 males, with a median age of 52 years. Among the cytological categories 80 (18.6%) were non-diagnostic (ND), 131 (30.2%) benign, 45 (10.4%) follicular lesion of undetermined significance (FLUS), 27 (6.3%) follicular neoplasm, 33 (7.9%) suspicious for malignancy (SM), and 115 (26.7%) malignant. Histopathology reports were available in 142 of these cases. Final malignant diagnosis was reported in 11 of 14 ND (78.6%), 5 of 18 benign cases (27.7%); 9 of 17 FLUS (52.9%), 7 of 13 FLUS (53.89%), 19 of 20 SM (95%), and 58 of 60 malignant cases (96.7%). The procedure had sensitivity of 94.4%, specificity of 61.9%, positive predictive value of 90.3% and negative predictive value of 72.22%. Conclusion: TBSRTC provides uniform categorization of thyroid cytology, which also helps in further management. This valid system has helped to streamline the reporting terminologies as well as the clinical management.

Role of Pathologist in the Era of Image-Guided and EUS-Guided Aspirations: A 10-Year Study at a Single Tertiary Care Oncology Institute in North India.

BACKGROUND: With improved and readily accessible imaging techniques, the shift in fine-needle aspiration cytology (FNAC) from palpation-guided FNA (PGFNA) to image-guided FNA (IGFNA) and endoscopic ultrasound-guided FNA (EUS-FNA) became evident in last few decades. The present study evaluates the impact of IGFNA and EUS-FNA on the practice of cytopathology at our 300-bedded oncology institute. STUDY DESIGN: A 10-year audit of three aspiration modalities PGFNA, IGFNA, and EUS-FNA was done. The number of aspirates, inadequacy rates, new patient registration numbers, and tissue biopsy numbers were compared. RESULTS: A total of 29,610 FNAC were evaluated against a total 141,333 new patient registrations over a period of 10 years. The new cancer patient registration over last 10 years showed a 56% increase, with a comparable increase of 60% in diagnostic biopsies; whereas, the number of FNAC increased by only 6%. This reduction in the number of aspirates was mainly due to fall in the number of PGFNA to 18% of all procedures in the year of 2019 from a high of 44% in 2011. Further, PGFNA showed a reduction by 50% over 3 years. The inadequacy rates of PGFNA increased to 9.1% (in 2019) from 1.6% (in 2012). The IGFNA constituted 46%-60% of procedures, with inadequacy varying from 8.5% to 12.1% over years. The EUS-FNAC gradually increased from 3% to 22% from 2013, and the inadequacy rates were variable overtime showing parallelism with the use of rapid on-site adequacy evaluation (ROSE) by the endoscopist. Inadequacy rates ranged from 7.1% (2013) to 2.6% (2016), 7.7% (2017), and 5.4% (2019). CONCLUSION: The utility of ROSE and diminishing role of pathologist is highlighted in our study. Judicious ROSE improves diagnostic accuracy, decreases the rate of missed diagnosis and the repetition of procedures. The study sheds light on the ever-increasing lacuna in the training of pathologists for blind as well as in image-guided FNAC. Further, it enumerates the factors leading to the underutilization of ROSE, its undisputed advantages, operator variations in procedure, smear preparation, and screening.

Reliability and Role of Mutation-specific H3F3A (Histone 3-3) G34W Immunohistochemistry to Differentiate Giant Cell Tumor of Bone From its Clinicoradiologic and Histologic Mimics: An Institutional Study.

Giant cell tumor of bone (GCTB) is a benign neoplasm, which can sometimes be a diagnostic challenge, especially in small biopsies, due to its histologic benign and malignant mimics. We evaluated the role of H3.3 G34W immunohistochemistry (IHC) antibody in diagnosing GCTB and its role in differentiating it from its close histologic mimics. A total of 120 cases (80 cases of GCTB and 40 cases of histologic mimics) were retrieved and subjected to IHC. Of 80 cases of GCTB, 72 cases showed a positive nuclear immunoexpression, while all 40 cases of histologic mimics of GCTB showed a negative staining for H3.3 G34W IHC. Sensitivity and specificity of this mutation-specific antibody for diagnosis of GCTB was 90% and 100%, respectively, while, the positive predictive value and the negative predictive value were 100% and 83.3%, respectively. A positive expression of H3.3 G34W was seen in all 5 cases of GCTB, postdenosumab therapy, as well as, in all 3 cases of malignant giant cell tumor. The presented study showed that H3.3 G34W mutation-specific IHC is a reliable and specific marker for GCTB and can help distinguish it from the histologic mimics due to distinct therapeutic implications.

High Grade Myoepithelial Carcinoma of Maxillary Sinus with Extensive Rhabdoid Differentiation and INI-1 Loss: Expanding the Histopathological Spectrum of Sinonasal Carcinoma.

Myoepithelial carcinoma (MEC) of salivary gland is an uncommon tumor with no specific age or sex predilection. Most of the cases (~90%) arise in parotid and submandibular glands followed by palate. MEC of maxillary sinus is rare. We describe an extremely rare case of high grade MEC with rhabdoid differentiation and INI-1 loss involving maxillary sinus of an elderly male.

Adamantinoma-like Ewing Sarcoma of the Nasal Cavity: A Rare Clinical Presentation with Deceptive Histopathologic Features.

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.

Eosinophilic solid and cystic renal cell carcinoma: A rare under-recognized indolent entity.

Eosinophilic solid and cystic renal cell carcinoma (ESCRCC) is an under-recognized, emerging new entity of sporadic renal neoplasms, with an approximate incidence of 0.2% of renal tumors. A total of 60 cases have been reported in the literature till date. ESCRCC are usually seen in adult females, with a low stage and indolent behavior, and rare incidence of recurrence or metastasis. They are solid and cystic tumors with variably sized cysts resembling eosinophilic RCC, showing a characteristic positive immune-expression for PAX-8, CK20 (in ~80% cases) and/or Melan-A (in ~6.7%), with negative CK7 and CA-IX expression. They consistently harbor TSC1 or TSC2 mutations in all tumors, which is a proposed molecular marker for this entity. We here present the first reported case of this rare tumor from India. The tumor was positive for PAX-8, and showed diffuse strong positivity for Melan-A, while was negative for CK7 and CK20. It was an early-stage tumor (T1), managed with partial nephrectomy, with no evidence of any recurrence/metastasis after 1 year of follow-up.