Atypical Spindle Cell and Pleomorphic Lipomatous Tumor of the Ocular Adnexa: Two Cases of a Rare Entity.

Atypical spindle cell and pleomorphic lipomatous tumor (ASCPLT) is a rare lipomatous neoplasm that was recently introduced into the World Health Organization Classification of Soft Tissue and Bone tumors as a distinct entity. ASCPLT has potential for local recurrence but does not metastasize. This biologic behavior separates ASCPLT from its morphologic mimics. Ocular adnexal ASCPLT has not been previously reported. Described herein are two patients with ASCPLT. The subcutaneous orbital rim lesion featured markedly pleomorphic spindle and multinucleated cells. The eyelid lesion was dominated by atypical spindle cells in a background of mature adipocytes. Both neoplasms demonstrated infiltrative margins, rare mitotic figures, immunoreactivity for CD34 and loss of Rb1, and the absence of MDM2 amplification by fluorescence in situ hybridization. Recognition of ASCPLT in the differential of ocular adnexal neoplasms may lead to a re-evaluation of morphologically similar tumors, which may have varied biologic behavior and warrant a different management approach.

Clinical, pathologic, and molecular analyses of superficial low-grade fibromyxoid sarcoma in two young patients: A rare and deceptive mimic of benignancy.

Low-grade fibromyxoid sarcoma (LGFMS) is a histopathologically deceptive soft tissue neoplasm with bland cytology, which is typically encountered in deep soft tissue of adults. We report two cases of superficial LGFMS in young patients (16 and 21 years old, respectively), which were difficult to diagnose on histopathologic and clinical findings alone. LGFMS commonly mimics benign neoplasms such as cellular neurothekeoma, fibromatosis, neurofibroma, and perineurioma. Malignancies included in the differential diagnosis are soft tissue neoplasms such as dermatofibrosarcoma protuberans and myxofibrosarcoma. A high degree of reported variation in pattern and cellularity among LGFMS further complicates the diagnosis. Careful examination and appropriate immunohistochemistry panels including MUC4 are essential for narrowing the differential diagnosis. Molecular studies for possible FUS translocation can confirm the diagnosis of LGFMS. Sufficient sampling and workup of these lesions are critical, especially in younger patients. Young age and superficial presentation can easily sway dermatopathologists/dermatologists toward an incorrect diagnosis of benignancy.

Metastatic Meningioma of the Neck: A Case Report and Systematic Review.

BACKGROUND: Although meningiomas are the most common central nervous system neoplasms, extracranial metastases are exceedingly rare. There are even fewer reports of metastatic meningiomas to the neck. METHODS: We described a patient with multiply recurrent orbital meningioma with metastasis to the neck found incidentally during neck exploration for composite resection and free tissue reconstruction. We performed a systematic review for all records pertaining to metastatic meningiomas to the cervical regions. RESULTS: We found 9 previous reports of cervical metastatic meningiomas. Almost all cases underwent extensive local resection. There was no evidence of an association between the histological grade of the tumor and risk of metastasis to the neck. Cervical lymph node dissemination is more common in patients presenting after previous primary tumor resection. CONCLUSIONS: In the context of a neck mass, our findings suggest that metastatic meningioma should be included in the differential diagnosis, especially in patients with previous resections.

The "Far Left" of the Morphologic Spectrum of Ovarian High-grade Serous Carcinoma: Case Report of a Purely Noninvasive High-grade Serous Carcinoma Mimicking an Ovarian Serous Borderline Tumor.

High-grade serous carcinoma has a variety of different growth patterns, but is typically easily recognizable to pathologists and rarely confused with serous borderline tumors. We report a case of a 71-yr-old woman with a unilateral 5.1 cm ovarian cyst with small papillary projections on contrast-enhanced magnetic resonance imaging of the pelvis. Histologic examination showed a noninvasive papillary neoplasm with hierarchical branching and epithelial proliferation, and thus, at low magnification, bearing a striking resemblance to a serous borderline tumor. However, a more careful examination demonstrated high-grade cytologic features, nuclear pleomorphism, and abundant mitotic activity, suggestive of high-grade serous carcinoma. The morphology and immunohistochemical profile of this lesion is consistent with a rare, purely noninvasive growth pattern of high-grade serous carcinoma. This lesion represents the "far left" of the high-grade ovarian serous carcinoma morphologic spectrum and can mimic a serous borderline tumor.

Dedifferentiated and undifferentiated neoplasms: A conceptual approach.

This review provides a conceptual approach to dedifferentiation across a variety of tumor types, with particular attention to genetic events that tie together morphologically disparate areas of these neoplasms. First, working definitions of the terms differentiated, undifferentiated, and dedifferentiated are developed. Then, specific examples of tumors with a particular propensity for undergoing dedifferentiation are highlighted, with emphasis on both immunohistochemical studies and molecular lesions that enable surgical pathologists to establish diagnostic clarity in morphologically vexing situations. Throughout this review, the historical arc of the literature is followed, and therefore the discussion of specific tumor types begins with dedifferentiated chondrosarcoma, the neoplasm that inspired the terminology regarding dedifferentiation that remains in use today. Selected other sarcomas with well-established pathways of dedifferentiation are subsequently discussed, followed by descriptions of this process in subtypes of carcinoma and melanoma.

Dynamic Aqueous Multiphase Reaction System for One-Pot CRISPR-Cas12a-Based Ultrasensitive and Quantitative Molecular Diagnosis.

Recently, CRISPR-Cas technology has opened a new era of nucleic acid-based molecular diagnostics. However, current CRISPR-Cas-based nucleic acid biosensing has a lack of the quantitative detection ability and typically requires separate manual operations. Herein, we reported a dynamic aqueous multiphase reaction (DAMR) system for simple, sensitive and quantitative one-pot CRISPR-Cas12a based molecular diagnosis by taking advantage of density difference of sucrose concentration. In the DAMR system, recombinase polymerase amplification (RPA) and CRISPR-Cas12a derived fluorescent detection occurred in spatially separated but connected aqueous phases. Our DAMR system was utilized to quantitatively detect human papillomavirus (HPV) 16 and 18 DNAs with sensitivities of 10 and 100 copies within less than 1 h. Multiplex detection of HPV16/18 in clinical human swab samples were successfully achieved in the DAMR system using 3D-printed microfluidic device. Furthermore, we demonstrated that target DNA in real human plasma samples can be directly amplified and detected in the DAMR system without complicated sample pretreatment. As demonstrated, the DAMR system has shown great potential for development of next-generation point-of-care molecular diagnostics.

Pathogenesis of Testicular Germ Cell Neoplasia: A Conceptual Approach.

Testicular germ cell tumors are a diverse group of neoplasms, consisting of the prepubertal type 1 tumors, pure teratoma, and pure yolk sac tumor, the type 2 tumors, which are biologically malignant, preceded by germ cell neoplasia in situ, and harbor chromosome 12p abnormalities, and the type 3 tumor, spermatocytic tumor, which features chromosome 9p amplification. These arise in distinct clinical settings, and harbor distinct genetic abnormalities, immunohistochemical properties, and morphologic features. Here we have attempted to unify embryology, morphology, immunohistochemistry, and genetics in order to distill this fascinating group of neoplasms into what we hope is a useful framework for understanding their classification.

Potential Diagnostic Pitfalls in Evaluating Immunohistochemistry for Cervical Myofibroblastomas.

Cervicovaginal myofibroblastoma (CVM) is a rare benign mesenchymal tumor of the lower female genital tract that shows chromosomal loss of 13q14 (RB1 gene located in this region). The aim of this study was to investigate the utility of immunohistochemistry (IHC) for desmin, CD34, and Rb in diagnosing CVM. All cervical polyps diagnosed from July 2016 to July 2017 were retrospectively reviewed. Cases showing morphologic myofibroblastic differentiation were evaluated by IHC for desmin, CD34, and Rb. Desmin and CD34 staining was recorded as positive or negative. Rb nuclear staining was graded as follows: 0 (<10%), 1 (10%-25%), 2 (>25%-50%), 3 (>50%-75%), or 4 (>75%). Intact nuclear expression of Rb in endothelial cells served as an internal positive control. IHC was performed on 76 cases with 14 excluded from the final cohort due to poor Rb internal control. A total of 61/62 (98.4%) cases were positive for desmin and CD34 with the following Rb distribution: grade 0 (n=53, 86.9%), grade 1 (n=5, 8.2%), grade 2 (n=2, 3.3%), and grade 3 (n=1, 1.6%). One case negative for desmin and CD34 showed grade 3 Rb staining. Upon rereview of the histology, 7/175 cases (4%) were morphologically and immunohistochemically compatible with CVM (desmin and CD34+ grade 0 Rb staining). CVM is a rare and under-recognized entity (4% of cervical polyps) for which morphology remains the mainstay of diagnosis. IHC reliance serves as a potential diagnostic pitfall as 86.9% of cases showing myofibroblastic differentiation demonstrated the staining pattern of desmin and CD34 positivity and Rb deficiency.

International Society of Gynecological Pathologists (ISGyP) Endometrial Cancer Project: Guidelines From the Special Techniques and Ancillary Studies Group.

The aim of this article is to propose guidelines and recommendations in problematic areas in pathologic reporting of endometrial carcinoma (EC) regarding special techniques and ancillary studies. An organizing committee designed a comprehensive survey with different questions related to pathologic features, diagnosis, and prognosis of EC that was sent to all members of the International Society of Gynecological Pathologists. The special techniques/ancillary studies group received 4 different questions to be addressed. Five members of the group reviewed the literature and came up with recommendations and an accompanying text which were discussed and agreed upon by all members of the group. Twelve different recommendations are made. They address the value of immunohistochemistry, ploidy, and molecular analysis for assessing prognosis in EC, the value of steroid hormone receptor analysis to predict response to hormone therapy, and parameters regarding applying immunohistochemistry and molecular tests for assessing mismatch deficiency in EC.

Radiomic features from MRI distinguish myxomas from myxofibrosarcomas.

BACKGROUND: Myxoid tumors pose diagnostic challenges for radiologists and pathologists. All myxoid tumors can be differentiated from each other using fluorescent in-situ hybridization (FISH) or immunohistochemical markers, except for myxomas and myxofibrosarcomas. Myxomas and myxofibrosarcomas are rare tumors. Myxomas are benign and histologically bland, whereas myxofibrosarcomas are malignant and histologically heterogenous. Because of the histological heterogeneity, low grade myxofibrosarcomas may be mistaken for myxomas on core needle biopsies. We evaluated the performance of T1-weighted signal intensity (T1SI), tumor volume, and radiomic features extracted from magnetic resonance imaging (MRI) to differentiate myxomas from myxofibrosarcomas. METHODS: The MRIs of 56 patients (29 with myxomas, 27 with myxofibrosarcomas) were analyzed. We extracted 89 radiomic features. Random forests based classifiers using the T1SI, volume features, and radiomic features were used to differentiate myxomas from myxofibrosarcomas. The classifiers were validated using a leave-one-out cross-validation. The performances of the classifiers were then compared. RESULTS: Myxomas had lower normalized T1SI than myxofibrosaromas (p = 0.006) and the AUC using the T1SI was 0.713. However, the classification model using radiomic features had an AUC of 0.885 (accuracy = 0.839, sensitivity = 0.852, specificity = 0.828), and outperformed the classification models using T1SI (AUC = 0.713) and tumor volume (AUC = 0.838). The classification model using radiomic features was significantly better than the classifier using T1SI values (p = 0.039). CONCLUSIONS: Myxofibrosarcomas are on average higher in T1-weighted signal intensity than myxomas. Myxofibrosarcomas are larger and have shape differences compared to myxomas. Radiomic features performed best for differentiating myxomas from myxofibrosarcomas compared to T1-weighted signal intensity and tumor volume features.

Epigenetic Alterations in Bone and Soft Tissue Tumors.

Human malignancies are driven by heritable alterations that lead to unchecked cellular proliferation, invasive growth and distant spread. Heritable changes can arise from changes in DNA sequence, or, alternatively, through altered gene expression rooted in epigenetic mechanisms. In recent years, high-throughput sequencing of tumor genomes has revealed a central role for mutations in epigenetic regulatory complexes in oncogenic processes. Through interactions with or direct modifications of chromatin, these proteins help control the accessibility of genes, and thus the transcriptional profile of a cell. Dysfunction in these proteins can lead to activation of oncogenic pathways or silencing of tumor suppressors. Although epigenetic regulators are altered across a broad spectrum of human malignancies, they play a particularly central role in tumors of mesenchymal and neuroectodermal origin. This review will focus on recent advances in the understanding of the molecular pathogenesis of a subset of tumors in which alterations in the polycomb family of chromatin modifying complexes, the SWI/SNF family of nucleosome remodelers, and histones play a central role in disease pathogenesis. Although this review will focus predominantly on the molecular mechanisms underlying these tumors, each section will also highlight areas in which an understanding of the molecular pathogenesis of these diseases has led to the adoption of novel immunohistochemical and molecular markers.

Can the Misinterpretation Amendment Rate Be Used as a Measure of Interpretive Error in Anatomic Pathology?: Implications of a Survey of the Directors of Anatomic and Surgical Pathology.

A repeat survey of the Association of the Directors of Anatomic and Surgical Pathology, done 10 years after the original was used to assess trends and variability in classifying scenarios as errors, and the preferred post signout report modification for correcting error by the membership of the Association of the Directors of Anatomic and Surgical Pathology. The results were analyzed to inform on whether interpretive amendment rates might act as surrogate measures of interpretive error in pathology. An analyses of the responses indicated that primary level misinterpretations (benign to malignant and vice versa) were universally qualified as error; secondary-level misinterpretations or misclassifications were inconsistently labeled error. There was added variability in the preferred post signout report modification used to correct report alterations. The classification of a scenario as error appeared to correlate with severity of potential harm of the missed call, the perceived subjectivity of the diagnosis, and ambiguity of reporting terminology. Substantial differences in policies for error detection and optimal reporting format were documented between departments. In conclusion, the inconsistency in labeling scenarios as error, disagreement about the optimal post signout report modification for the correction of the error, and variability in error detection policies preclude the use of the misinterpretation amendment rate as a surrogate measure for error in anatomic pathology. There is little change in uniformity of definition, attitudes and perception of interpretive error in anatomic pathology in the last 10 years.

Epidermal growth factor receptor pathway mutation and expression profiles in cervical squamous cell carcinoma: therapeutic implications.

BACKGROUND: Cervical squamous cell carcinoma (CSCC) is a major cause of female mortality worldwide. This study has examined epidermal growth factor receptor (EGFR) pathway markers that represent actionable pharmacological targets. METHODS: HPV16 positive CSCCs (n = 105 patients) from Madhya Pradesh, India were screened for KRAS and PIK3CA mutations by PNA-clamp real-time PCR. Immunohistochemistry (IHC) was performed for EGFR, PIK3CA, PTEN, phospho-AKT, phospho-mTOR and phospho-44/42 MAPK (ERK1/2). RESULTS: KRAS mutations were detected in 0/91 (0%) and PIK3CA mutations in 19/95 (20.0%) informative specimens: exon 9, E542 (n = 3) and E545 (n = 15); exon 20, H1047R (n = 1). PIK3CA mutation detection was associated with older mean patient age [48.2 vs. 56.6 years (P = 0.007)] and with post-menopausal age: 5/45 (11.1%) patients <50 years vs. 14/50 (28.0%) patients ≥50 years (P = 0.045; OR = 3.11). EGFR expression was present in 60/101 (59.4%) CSCCs and was associated with PIK3CA mutation detection (P < 0.05) but not age (P > 0.05). EGFR and phospho-AKT staining showed associations with tumor grade and/or lymph node status (P < 0.05). Significant associations were not found for the other study markers (P > 0.05). CONCLUSION: These data show that PIK3CA mutation acquisition is related to patient age and EGFR expression. The absence of KRAS mutations supports the potential of anti-EGFR therapies for CSCC treatment. The relatively high PIK3CA mutation rates indicate that PI3K may be a therapeutic target for a significant subset of CSCC patients. Qualitatively distinct IHC staining profiles for the marker panel were noted patient to patient; however, across patients, consistent linear relationships between up- and downstream pathway markers were not observed. Evaluation of the expression status of potential cancer pathway targets may be of value in addition to molecular profiling for choosing among therapeutic options.

Human papillomavirus type distribution in invasive cervical cancers from Madhya Pradesh: implications for vaccination programs in central India.

Invasive cervical carcinoma (ICC) remains a leading cause of female mortality in India. There is a paucity of data about human papillomavirus (HPV) type distribution among ICCs from Central India. Formalin-fixed, paraffin-embedded ICC specimens (n=270 patients) from Madhya Pradesh state were screened for HPV by GP5/6 primer-based polymerase chain reaction followed by cycle sequencing and NCBI BLAST search. HPV was detected in 93.3% of the tumors. Thirteen types were detected: HPV16 (73.7%), HPV18 (11.9%), HPV45 (2.2%), HPV66 (1.5%), HPV35 (1.1%), and HPV56 (0.7%). HPV31, 51, 58, 59, 67, 82 and JEB2 were each seen in 1 case (0.4%). HPV16 was more common among women less than 40 yr than 40 yr or older (P=0.006), and HPV18 was more common in women aged 40 yr or older (P=0.013). Squamous cell carcinomas were more frequently HPV-positive than adenocarcinomas (P=0.01). HPV18 was more common in adenocarcinoma than in squamous cell carcinoma (P=0.02). These data contribute to the pan-India profile of HPV-type relationship to ICC and show the potential of current vaccines to greatly relieve (by up to 85.6%) the ICC burden in Central India. The findings are also suggestive that next-generation HPV vaccines might be designed on a regional basis rather than from compounded global data.

Mycobacterial spindle cell pseudotumor of the spinal cord: Case report and literature review.

We report the first description of spinal cord mycobacterial spindle cell pseudotumor. A patient with newly diagnosed advanced HIV presented with recent-onset bilateral leg weakness and was found to have a hypermetabolic spinal cord mass on structural and molecular imaging. Biopsy and cultures from blood and cerebrospinal fluid confirmed spindle cell pseudotumor due to Mycobacterium avium-intracellulare. Despite control of HIV and initial reduction in pseudotumor volume on antiretrovirals and antimycobacterials (azithromycin, ethambutol, rifampin/rifabutin), he ultimately experienced progressive leg weakness due to pseudotumor re-expansion. Here, we review literature and discuss multidisciplinary diagnosis, monitoring and management challenges, including immune reconstitution inflammatory syndrome.

Sarcoma Cells Secrete Hypoxia-Modified Collagen VI to Weaken the Lung Endothelial Barrier and Promote Metastasis.

Intratumoral hypoxia correlates with metastasis and poor survival in patients with sarcoma. Using an impedance sensing assay and a zebrafish intravital microinjection model, we demonstrated here that the hypoxia-inducible collagen-modifying enzyme lysyl hydroxylase PLOD2 and its substrate collagen type VI (COLVI) weaken the lung endothelial barrier and promote transendothelial migration. Mechanistically, hypoxia-induced PLOD2 in sarcoma cells modified COLVI, which was then secreted into the vasculature. Upon reaching the apical surface of lung endothelial cells, modified COLVI from tumor cells activated integrin ß1 (ITGß1). Furthermore, activated ITGß1 colocalized with Kindlin2, initiating their interaction with F-actin and prompting its polymerization. Polymerized F-actin disrupted endothelial adherens junctions and induced barrier dysfunction. Consistently, modified and secreted COLVI was required for the late stages of lung metastasis in vivo. Analysis of patient gene expression and survival data from The Cancer Genome Atlas (TCGA) revealed an association between the expression of both PLOD2 and COLVI and patient survival. Furthermore, high levels of COLVI were detected in surgically resected sarcoma metastases from patient lungs and in the blood of tumor-bearing mice. Together, these data identify a mechanism of sarcoma lung metastasis, revealing opportunities for therapeutic intervention. SIGNIFICANCE: Collagen type VI modified by hypoxia-induced PLOD2 is secreted by sarcoma cells and binds to integrin ß1 on endothelial cells to induce barrier dysfunction, which promotes sarcoma vascular dissemination and metastasis.

Anisometric Cell/Dysplastic Lipomas in a Retinoblastoma Survivor: Report of a Case with Review of the Literature.

Different authors have recently described a subtype of lipoma characterized by variation of adipocyte size, single cell fat necrosis, and a subset with minimal to mild nuclear atypia, and termed these as anisometric cell/dysplastic lipoma (AC/DL). These lipomas follow a benign course and rarely recur. In 3 examples, AC/DL has occurred in patients with childhood retinoblastoma (RB). We report another such example where multiple AC/DL occurred in the neck and back of a 30-year-old male who had germline RB1 gene deletion and bilateral RB in infancy. On excision, all tumors histologically showed similar morphology of adipocyte anisometry, focal single cell necrosis with surrounding binucleated or multinucleated histiocytes, hyperchromatic and minimally atypical lipocyte nuclei, vacuolated Lockhern change, rare foci of fibromyxoid change, occasional mononuclear cell clusters around capillaries, and loss of RB1 immunostaining. Unequivocal atypical cells, lipoblasts, floret-nucleated or multinucleated giant cells were absent. Molecular analysis of tumor cells showed monoallelic RB1 gene loss without amplification of MDM2 and CDK4 genes. Short-term follow up did not show tumor recurrence. AC/DLs in RB survivors are characterized by multiplicity, unifying histology, and benign course. Their biology appears distinct from ordinary lipomas, spindle cell lipomas, and atypical lipomatous tumors.

Myofibroblastoma in the Liver: A Case Report and Review of Literature.

Myofibroblastoma is a rare benign mesenchymal tumor first described in the breast. It is also known as mammary-type myofibroblastoma outside of the breast, more frequently located along the embryonic milk line. Exceptionally, myofibroblastoma can occur at visceral locations. We present a case of myofibroblastoma detected incidentally in the liver. A well-circumscribed mass, grossly measuring 6.2 cm in the liver parenchyma, was found on imaging studies. Histologically, the lesion is characterized by benign spindle cells in a hyalinized collagenous stroma, with positive staining for SMA and ER, focal positivity for CD34, negative for desmin, and loss of RB1. This rare tumor at such an unusual location makes it diagnostically challenging, especially on core biopsy of the lesion. To our knowledge, this is the second case of myofibroblastoma in the liver reported in the English literature and the first such case with a detailed pathology description.

Primary Alveolar Soft-Part Sarcoma (ASPS) of the Prostate: Report of a Deceptive Case.

Alveolar soft-part sarcoma (ASPS) is a rare soft tissue tumor that primarily involves the extremities. We report a case of a 30-year-old never-smoker man who presented with hematuria, dysuria, and constipation at an outside hospital. He was diagnosed with and treated for multiple episodes of urinary tract infection. However, he continued to have voiding symptoms for which a cystoscopy was performed and revealed a bladder neck mass. He underwent transurethral resection of a bladder tumor and was diagnosed with muscle-invasive urothelial carcinoma, nested variant, at an outside hospital. Subsequent to this diagnosis he transferred his care to our center. In-house imaging revealed a large vascular mass involving the prostate and pushing against the bladder base. Prostate needle biopsies were performed and revealed an epithelioid neoplasm with a nested growth pattern composed of cells with a moderate amount of eosinophilic cytoplasm, mildly pleomorphic nuclei, and occasional prominent nucleoli. Since the findings were not classic for urothelial carcinoma or for prostate cancer, we included a wider differential of poorly differentiated carcinoma, sarcoma, and paraganglioma. A wide panel of keratin stains was negative, ETS (erythroblast transformation-specific)-related gene highlighted an extensive vascular network and neuroendocrine stains were all negative. A transcription factor E3 fluorescent in-situ hybridization was positive and subsequently, an ASPSCR1 gene rearrangement was demonstrated. The outside hospital transurethral resection of bladder tumor was obtained for review and the tumor was morphologically similar to that seen on the in-house prostate needle biopsies. Based on the above findings a final diagnosis of primary ASPS of the prostate with involvement of the bladder was made. The patient was later diagnosed with bilateral lung metastases. He was treated with pazopanib, radiation therapy, and cystoprostatectomy and is symptom-free on a 15-month follow-up.

Identifying Lynch syndrome in patients with endometrial carcinoma: shortcomings of morphologic and clinical schemas.

It has been suggested that reflex testing for Lynch syndrome (LS) using mismatch repair immunohistochemistry and/or microsatellite instability analysis in newly diagnosed colorectal carcinoma (CRC) patients is an emerging standard of care in the United States. The risk of gynecologic malignancy in women with LS approaches and even exceeds that of CRC. Furthermore, gynecologic malignancies are often the sentinel cancers in these patients. There is significant variation in practice, but some groups have similarly recommended deployment of reflex testing strategies in patients presenting with endometrial cancer (EC). The College of American Pathologists has stated that pathologists should recognize the histologic and clinical features that should prompt at least a recommendation for mismatch repair testing. Morphologic and clinical schemas in EC to identify microsatellite unstable/LS tumors are less refined than the colon-centric schemas (Amsterdam, Bethesda, and MsPath). Studies of LS EC are few and interpretation is limited by recruitment strategies and the myriad of definitions and study designs used. Although serous cell type is used to triage ovarian cancer patients for BRCA screening, cell type correlation in LS is less certain but seems to involve a spectrum of cell types. We review the morphologic and clinical features/schemas in LS EC and highlight limitations of restrictive aged-based screening strategies, uncertainty in current clinical schemas and equivocal results of morphologic studies of LS EC. With uncertainty of histologic and clinical schemas, and following developments in CRC, reflex testing of all/vast majority of newly diagnosed EC for LS should be considered.