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Embryonal Rhabdomyosarcoma of the Uterine Cervix: A Clinicopathologic Study of 94 Cases Emphasizing Issues in Differential Diagnosis Staging, and Prognostic Factors
This study highlights the intriguing clinical aspects of cERMS including its long-known tendency to occur in the young but also more recently appreciated association with DICER1 syndrome. Establishing the diagnosis may still be difficult because of the hazard of sampling a neoplasm which in areas may appear remarkably bland and also because of its potential confusion with other neoplasms. This study indicates that this tumor has a good prognosis at this site and in selected cases a conservative surgical approach is a realistic consideration. (Source: The American Journal of Surgical Pathology)
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

PRAME Expression in Cancer. A Systematic Immunohistochemical Study of >5800 Epithelial and Nonepithelial Tumors
Preferentially expressed antigen in melanoma (PRAME) is considered a useful marker in the differential diagnosis between malignant melanoma and its melanocytic mimics. Recently PRAME expression was documented in nonmelanocytic tumors, but much of the data are based on mRNA studies. This investigation evaluated PRAME expression in the spectrum of normal tissues and>5800 human tumors using immunohistochemistry and EP461 monoclonal antibody. In normal tissues, PRAME was expressed in the testis and proliferative endometrium. In tumors, PRAME was variably expressed in malignancies of different lineages. Among epithelial tumors,...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

Cutaneous Melanocytic Tumor With CRTC1::TRIM11 Translocation: An Emerging Entity Analyzed in a Series of 41 Cases
Cutaneous melanocytic tumor with CRTC1::TRIM11 fusion (CMTCT) is a recently described dermally based neoplasm with melanocytic differentiation. It can easily be confused with clear cell sarcoma and metastatic melanoma. Our understanding of this lesion, including its potential for aggressive disease, has been limited by the small number of previously reported cases (13) and the limited clinical follow-up data. Here, we report a series of 41 CMTCT confirmed by molecular studies. We find that the lesion shows highly uniform and reproducible morphologic, immunohistochemical, and genetic features across a wide variety of anatom...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

Morules But Not Squamous Differentiation are a Reliable Indicator of CTNNB1 (β-catenin) Mutations in Endometrial Carcinoma and Precancers
Although collectively regarded as “squamous differentiation (SD)” in endometrial endometrioid carcinoma (EEC) and atypical hyperplasia/endometrioid intraepithelial neoplasia (AH/EIN), morules (often referred to as “squamous morules”) and true SD may represent two distinct phenomena. Here, we explored the distinction between morules versus SD and investigated the association of morules and SD with CTNNB1 mutations. A total of 270 cases of EEC and AH/EIN were studied, including EEC with (n=36) or without (n=36) morules and AH/EIN with (n=80) or without (n=118) morules. Cases were analyzed by immunohistochemistry and ...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

Gastroesophageal Glomus Tumors: Clinicopathologic and Molecular Genetic Analysis of 26 Cases With a Proposal for Malignancy Criteria
Although criteria for malignancy have been established for glomus tumors of soft tissue, there are no accepted criteria for gastroesophageal glomus tumors, the behavior of which is considered to be unpredictable. Recently, both benign and aggressive gastroesophageal glomus tumors have been shown to harbor CARMN::NOTCH2 fusions, but, as yet, there are no described genetic features that predict clinical behavior. Here, we evaluated 26 gastroesophageal glomus tumors to investigate histologic and genetic features that might predict malignant behavior. Seventeen patients (65%) were male. The median age at presentation was 54.5 ...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

“Malignant Mesenchymoma” Revisited: A Clinicopathologic Study of Leiomyosarcomas With Osteosarcomatous Differentiation
Leiomyosarcoma (LMS) is the most common sarcoma in adults. Rarely, LMS dedifferentiates into an undifferentiated sarcoma. Very few cases of LMS with heterologous osteosarcomatous differentiation (OS) have been reported. The purpose of this study was to evaluate the clinicopathologic features of LMS with OS. Of 5570 LMS cases diagnosed from 2006 to 2022, 15 cases (0.2%) of LMS with OS were identified, affecting 13 females and 2 males; ages ranged from 32 to 66 years (median: 53 y). Ten tumors arose in the uterus, 2 in the retroperitoneum, and 1 each in the mesentery, mediastinum, and rectum. Primary tumors ranged from 7 to...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

NTRK-Rearranged Uterine Sarcomas: Clinicopathologic Features of 15 Cases, Literature Review, and Risk Stratification
This study expands the morphologic spectrum of NTRK-rearranged uterine sarcomas and identifies features which can be used for risk stratification. (Source: The American Journal of Surgical Pathology)
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

GRM1 Immunohistochemistry Distinguishes Chondromyxoid Fibroma From its Histologic Mimics
Chondromyxoid fibroma (CMF) is a rare benign bone neoplasm that manifests histologically as a lobular proliferation of stellate to spindle-shaped cells in a myxoid background, exhibiting morphologic overlap with other cartilaginous and myxoid tumors of bone. CMF is characterized by recurrent genetic rearrangements that place the glutamate receptor gene GRM1 under the regulatory control of a constitutively active promoter, leading to increased gene expression. Here, we explore the diagnostic utility of GRM1 immunohistochemistry as a surrogate marker for GRM1 rearrangement using a commercially available monoclonal antibody i...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

Pediatric-Type Indolent B-Cell Lymphomas With Overlapping Clinical, Pathologic, and Genetic Features
Pediatric-type follicular lymphoma (PTFL) and pediatric nodal marginal zone lymphoma (PNMZL) are rare pediatric-type indolent B-cell lymphomas (PedIBCL) that differ clinicopathologically from their adult counterparts. Accurate diagnosis is important to avoid overtreatment but is often challenging. The mutational landscape of PTFL is known and may aid diagnosis, but the genetic features of PNMZL are not well understood. We analyzed 21 cases of PedIBCL according to their clinicopathologic findings and classified them into PTFL (n=11), PNMZL (n=2), and “mixed type” tumors (n=8) showing ambiguous histology. We also analyze...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

Enhanced PD-L1 Expression in LMP1-positive Cells of Epstein-Barr Virus–associated Malignant Lymphomas and Lymphoproliferative Disorders: A Single-cell Resolution Analysis With Multiplex Fluorescence Immunohistochemistry and In Situ Hybridization
Epstein-Barr virus (EBV) is associated with various types of human malignancies and with programmed death ligand (PD-L) 1 expression in neoplastic cells. However, in EBV-associated malignant lymphomas and lymphoproliferative disorders (LPDs), there is limited information regarding PD-L1 expression profiles among different histologic types and patterns of EBV latency. First, we investigated PD-L1 and EBV latent gene expression using conventional immunohistochemistry and in situ hybridization in 42 EBV-associated malignant lymphomas and LPDs. Classic Hodgkin lymphoma showed the highest PD-L1 expression with diffuse expressio...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

Prominent Pseudoacini in Focal Nodular Hyperplasia: A Potential Diagnostic Pitfall
Pseudoacini are generally a morphologic feature of hepatocellular carcinoma (HCC), being absent or rare in benign hepatocytic tumors, such as hepatocellular adenoma. However, rarely these can be seen in focal nodular hyperplasia (FNH) and may pose diagnostic challenges, especially when prominent. The study was aimed to evaluate the occurrence of pseudoacini in FNH and their clinicopathologic correlations. A total of 95 FNH cases diagnosed from 2005 to 2020 were included in the study. A pseudoacinus was defined as a circular arrangement of hepatocytes around a central dilated lumen present within the lobular parenchyma of t...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

Clinicopathologic and Molecular Characterization of Epstein-Barr Virus–positive Plasmacytoma
Epstein-Barr virus (EBV)-positive plasmacytoma is a rare plasma cell neoplasm. It remains unclear whether EBV-positive plasmacytoma represents a distinct entity or a variant of plasmacytoma. It shares morphologic features with plasmablastic lymphoma (PBL) and may cause diagnostic uncertainty. To better understand EBV-positive plasmacytoma and explore diagnostic criteria, this study describes 19 cases of EBV-positive plasmacytoma, compared with 27 cases of EBV-negative plasmacytoma and 48 cases of EBV-positive PBL. We reviewed the clinicopathologic findings and performed immunohistochemistry, in situ hybridization for EBV, ...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

Localized Malignant Peritoneal Mesothelioma (LMPeM) in Women: A Clinicopathologic Study of 18 Cases
In this study, we present our experience with 18 cases seen in our hospital over a period of 43 years (1978 to 2021). Patients’ median age was 55 years (y) (range: 33 to 79 y) and most of them were Caucasians. Patients presented with abdominal pain (11), ascites and right leg swelling (1), abdominal mass (1), and as incidental finding (1). Thirty percent of patients reported asbestos exposure, and all patients with available information had family history of tumors; a third had personal history of tumors. Seventy-seven percent had some form of abdominopelvic surgery and/or inflammatory process. Most cases had microscopi...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

A Novel Combined Tumor Budding-Poorly Differentiated Clusters Grading System Predicts Recurrence and Survival in Stage I-III Colorectal Cancer
Tumor budding (TB) and poorly differentiated clusters (PDCs) are powerful prognostic factors in colorectal cancer (CRC). Despite their morphologic and biological overlap, TB and PDC are assessed separately and are distinguished by an arbitrary cutoff for cell cluster size. This cutoff can be challenging to apply in practice and its biological significance remains unclear. We developed a novel scoring system that incorporates TB and PDC into a single parameter (“Combined Score”; CS), eliminating the need for such cutoffs and allowing the prognostic value of PDC to be captured alongside TB. In a cohort of 481 stage I-III...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

Superficial CD34-Positive Fibroblastic Tumor: A Clinicopathologic, Immunohistochemical, and Molecular Study of 59 Cases
This study characterizes the clinicopathologic, immunohistochemical, and molecular features of SCD34FT in a series of 59 cases. Fluorescence in situ hybridization to assess for PRDM10 rearrangement was performed in 12 tumors. Immunohistochemistry for CADM3 and WT1 was performed; CADM3 was also assessed in histologic mimics. Our cohort of 33 male and 26 female had a median age of 42 (range: 14 to 85) years. Tumors were most commonly located in the lower limb (73%), upper limb (8%), back (7%), and supraclavicular region (3%). The median tumor size was 3.0 cm (range: 1.0 to 9.0 cm). Clinical follow-up in 32 patients (median...
Source: The American Journal of Surgical Pathology - September 23, 2022 Category: Pathology Tags: Original Articles Source Type: research