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Ovarian Signet-ring Stromal Tumor: A Morphologic, Immunohistochemical, and Molecular Study of 7 Cases With Discussion of the Differential Diagnosis
We report 10 ovarian stromal neoplasms originally diagnosed as SRST. All but 1 tumor underwent detailed immunohistochemical analysis (including β-catenin) and 5 of 10 had CTNNB1 mutation analysis performed. All tumors contained a population of morphologically bland signet-ring cells that ranged from 15% to 95% of the neoplasm, characterized by a single large empty intracytoplasmic vacuole, mostly with nuclear indentation. Six of the 10 tumors contained cellular fibroma-like areas, comprising from 10% to 85% of the neoplasm. Three of the 10 tumors were reclassified as microcystic stromal tumor with signet-ring cells on the...
Source: The American Journal of Surgical Pathology - November 23, 2022 Category: Pathology Tags: Original Articles Source Type: research

Biphasic Hyalinizing Psammomatous Renal Cell Carcinoma (BHP RCC) in a Child With Neurofibromatosis Type 2 Syndrome
No abstract available (Source: The American Journal of Surgical Pathology)
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Letters to the Editor Source Type: research

Response to: Langerhans Cell Histiocytosis Associated With Renal Cell Carcinoma: Is it an Indolent Phenomenon or a More Ominous Pathologic Process?
No abstract available (Source: The American Journal of Surgical Pathology)
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Letters to the Editor Source Type: research

Langerhans Cell Histiocytosis Associated With Renal Cell Carcinoma: Is it an Indolent Phenomenon or a More Ominous Pathologic Process?
No abstract available (Source: The American Journal of Surgical Pathology)
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Letters to the Editor Source Type: research

Dataset for the Reporting of Merkel Cell Carcinoma: Recommendations From the International Collaboration on Cancer Reporting (ICCR)
In this study, data elements for pathologic reporting of MCC were analyzed by an international panel of pathologists and clinicians with the aim of developing a common, internationally agreed upon dataset useful for clinical practice. The International Collaboration on Cancer Reporting expert review panel developed a protocol containing “core” (required) and “noncore” (recommended) elements. Core elements were defined as those that had evidentiary support and were unanimously agreed upon by the review panel as essential for the clinical management, staging, and/or assessment of prognosis in patients with MCC. Nonco...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

Brown Tumors Belong to the Spectrum of KRAS-driven Neoplasms
Brown tumors are rare and generally self-limiting mass lesions of bone occurring in the context of hyperparathyroidism. Although commonly regarded as endocrine-driven tumor-like lesions, we detected pathogenic hotspot KRAS mutations in 10/16 brown tumors (62%) with similar frequencies found in cases affecting the peripheral and axial skeleton. Pathogenic mutations in other driver genes of the RAS-MAPK pathway were not identified. Our findings suggest brown tumors to represent true neoplasms driven by the activation of the RAS-MAPK signaling pathway. The frequent regression of brown tumors after normalization of hyperparath...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

TSC/MTOR-associated Eosinophilic Renal Tumors Exhibit a Heterogeneous Clinicopathologic Spectrum: A Targeted Next-generation Sequencing and Gene Expression Profiling Study
Conclusions: We expanded the TSC/MTOR-associated eosinophilic renal tumor morphologic spectrum, identified gene mutation characteristics, and highlighted differential diagnosis challenges, especially with MiT RCC. ESC RCC, EVT, and LOT having distinct expression profiles. TSC-mt RCC-NOS may cluster with recognized TSC/MTOR-associated entities. (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

Xanthomatous Giant Cell Renal Cell Carcinoma: Another Morphologic Form of: TSC: -associated Renal Cell Carcinoma
We report herein two distinctive TSC2-mutated renal cell carcinomas which do not fit any previously described entity. The two renal carcinomas occurred in young patients (ages 10 and 31 y), and were characterized by highly permeative growth within the kidney with metastases to perirenal lymph nodes. The neoplastic cells were predominantly large, multinucleated giant cells having variably eosinophilic to xanthomatous cytoplasm with basophilic stippling and frequent vacuolization. While the discohesive nature of the neoplastic cells, xanthomatous cytoplasm, immunoreactivity for histiocytic markers and minimal immunoreactivi...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

The Clonal Relationship Between the Ductal and Lobular Components of Mixed Ductal-Lobular Carcinomas Suggested a Ductal Origin in Most Tumors
In this study, the molecular alterations of both components were analyzed in a series of 20 IDLC that were selected, not only by morphologic criteria, but also by the loss of E-cadherin expression in the lobular component. We found that 80% of tumors shared alterations of driver genes in both components, being PIK3CA the most common alteration. In addition, 45% of IDLC carried CDH1 mutations in their lobular component that were absent in the ductal component. Fluorescent in situ hybridization analysis of the CDH1 gene excluded homozygous CDH1 loss as a frequent cause of E-cadherin loss in tumors without CDH1 mutations. In ...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

Clinicopathologic Features and Genomic Signature of De Novo CD5+ Diffuse Large B-Cell Lymphoma: A Multicenter Collaborative Study
De novo CD5+ diffuse large B-cell lymphoma (DLBCL) has poor survival in the era of immunochemotherapy. Accurate gene-based typing and prognostic stratification can enhance the development of effective individualized treatments. Therefore, we conducted a multicenter retrospective study to evaluate the clinicopathologic characteristics, genomic profiles, and prognostic parameters of 61 patients with CD5+ DLBCL and 60 patients with CD5− DLBCL, with the goal of facilitating accurate prognostic stratification and potential individualized treatment strategies. Compared with patients with CD5− DLBCL, older age, advanced stage...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

Invasive Mucinous Adenocarcinoma of the Lung With a Mural Nodule-like Lesion
In this study, we analyzed 213 surgically resected cases of IMA of the lung to determine whether similar mural nodule–like lesions were present. We considered abrupt discrete lesions composed of dedifferentiated tumor cells as mural nodule–like lesions. Of 213 IMAs, we identified 11 tumors with mural nodule–like lesions that were histologically categorized into three subtypes similar to those in the ovary. The sarcomatoid and anaplastic carcinoma–like nodules were composed of spindle cell proliferations and polygonal undifferentiated carcinoma, respectively. Sarcoma-like lesions mimicked sarcomatoid nodules, but th...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

MUM1/IRF4 is Highly Expressed in Dermatopathic Lymphadenopathy: Potential Utility in Diagnosis and Differential Diagnosis
Dermatopathic lymphadenopathy (DL) is a distinctive type of lymph node hyperplasia that typically occurs in the setting of chronic dermatologic diseases. DL generally self-resolves following disappearance of the underlying skin stimulus and does not require any specific therapy. We recently observed multiple myeloma oncogene 1/interferon regulatory factor 4 (MUM1/IRF4) expression in a case of DL using immunohistochemical methods. The goal of this study was to systematically assess DL cases for MUM1/IRF4 expression and to survey other histiocytic and Langerhans cell lesions. We particularly focused on Langerhans cell histio...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

CD163 Immunohistochemical “Circle Sign” Staining Pattern Differentiates Sinonasal Papillomas From Morphologically Similar Non-neoplastic Lesions
Sinonasal papillomas are a diverse group of benign epithelial neoplasms of the sinonasal tract. Inverted papilloma, in particular, must be distinguished from other lesions with no malignant potential. The aim of this study was to distinguish sinonasal papillomas from morphologically similar lesions using CD163 immunostaining. Cases from a 19-year period were identified. These included 49 inverted, 10 exophytic, and 12 oncocytic papillomas, 21 chronic sinusitides with squamous metaplasia, 27 inflammatory polyps, 5 verrucae vulgares, 5 respiratory epithelial adenomatoid hamartomas, and 6 DEK::AFF2 carcinomas of the sinonasal...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

Histologic Variants of Kaposi Sarcoma in the Gastrointestinal Tract: A Contemporary Multi-institutional Clinicopathologic Analysis of 46 Cases
Kaposi sarcoma (KS) can pose diagnostic challenges in biopsy specimens. Multiple histologic variants of cutaneous KS have been described; however, the histomorphologic spectrum of gastrointestinal (GI) KS has not been systematically studied. This large series comprehensively evaluated 46 cases of KS involving the GI tract and identified 7 histomorphologic variants, some that have not been previously described. Five of them are inconspicuous but have unique morphologic patterns, including lymphangioma/lymphangiectatic–like (n=17), mucosal hemorrhage/telangiectatic–like (n=17), mucosal inflammation–like (n=15), granula...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research

Immunohistochemical Approach to Genetic Subtyping of Anaplastic Large Cell Lymphoma
Anaplastic large cell lymphoma (ALCL) can be classified genetically based on rearrangements (R) of the ALK, TP63, and/or DUSP22 genes. ALK-R defines a specific entity, ALK-positive ALCL, while DUSP22-R and TP63-R define subgroups of ALK-negative ALCLs with distinct clinicopathologic features. ALK-R and TP63-R produce oncogenic fusion proteins that can be detected by immunohistochemistry. ALK immunohistochemistry is an excellent surrogate for ALK-R and screening with p63 immunohistochemistry excludes TP63-R in two third of ALCLs. In contrast, DUSP22-R does not produce a fusion protein and its identification requires fluores...
Source: The American Journal of Surgical Pathology - October 20, 2022 Category: Pathology Tags: Original Articles Source Type: research