Histological and photoacoustic evaluation of rectal cancer after neoadjuvant therapy using microvascular density.

AIM: As non-operative management of rectal cancer proliferates, re-staging and surveillance methods are critical in selecting appropriate patients for organ preservation versus proctectomy. In previous work, the authors have shown that transrectal acoustic resolution photoacoustic microscopy (ARPAM) co-registered with ultrasound can differentiate residual cancer from complete tumoural response to neoadjuvant therapy. We hypothesize that these findings are due to changes in microvascular density (MVD). METHODS: Patients with rectal adenocarcinoma who underwent neoadjuvant therapy, transrectal photoacoustic imaging and resection were included. We first compared immunohistochemical staining with erythroblast transformation-specific-related gene (ERG) immunostain to standard CD31 to confirm adequate identification of endothelium. Tissue sections from identical blocks were stained with CD31 and ERG, and then a correlation was calculated between manually labelled CD31-stained vessels and ERG nuclei density. Second, representative tissue blocks from responders, partial responders and non-responders were stained with ERG. ERG nuclei density was quantified as a proxy for MVD. RESULTS: CD31 MVD and ERG nuclei density were strongly correlated (R2 = 0.87; P < 0.01). In the tumour bed of patients after neoadjuvant therapy, MVD of complete responders (599 nuclei/mm2; 95% CI 434-764) is significantly higher (P < 0.01) than that of partial responders (185 nuclei/mm2; 95% CI 64-306) and non-responders (117 nuclei/mm2; 95% CI 42-192). No significant difference was found between the partial responders and non-responders (P = 0.60). CONCLUSION: Microvascular density appears highest in cases of complete tumour response to neoadjuvant therapy, similar to normal rectal tissue. The histological microvascular patterns seen in treated tissue may explain the imaging patterns seen in photoacoustic microscopy.

Well-differentiated neuroendocrine tumors of the appendix: Diagnosis, differentials, and disease progression.

Well-differentiated neuroendocrine tumors are the most common neoplasm of the appendix. They are graded and staged using World Health Organization and American Joint Committee on Cancer criteria, respectively. They may be invisible grossly or form rounded yellow nodules, sometimes in the appendiceal tip. They show classic neuroendocrine tumor features microscopically, forming nests and cords of monotonous cells with salt-and-pepper chromatin and amphophilic cytoplasm. They are positive for neuroendocrine markers by immunohistochemistry, but their molecular characteristics are not well defined. pT-category staging relies primarily on tumor size, though higher-stage cases may involve the subserosa or mesoappendix. Few entities enter the differential diagnosis, but lesions such as goblet cell adenocarcinoma, poorly differentiated neuroendocrine carcinoma, and mixed neuroendocrine-non-neuroendocrine neoplasm may be considered. Appendiceal neuroendocrine tumors may metastasize to regional lymph nodes, but farther spread is rare. The most consistently proven risk factor for such spread is tumor size, though different studies have proposed different cutoffs. Other potential risk factors include lymphovascular invasion and margin positivity. Tumors smaller than 1 cm can be treated by appendectomy, while hemicolectomy is recommended for tumors larger than 2 cm. Proper treatment for cases measuring 1-2 cm remains a matter of debate.

Integrated Genomic and Clinicopathologic Approach Distinguishes Pancreatic Grade 3 Neuroendocrine Tumor From Neuroendocrine Carcinoma and Identifies a Subset With Molecular Overlap.

Distinguishing grade 3 pancreatic neuroendocrine tumor (G3 PanNET) from neuroendocrine carcinoma (PanNEC) is a known diagnostic challenge, and accurate classification is critical because clinical behavior and therapies differ. Although current recommendations suggest that immunohistochemistry for p53, Rb, ATRX, and DAXX can distinguish most cases, some cases remain difficult to classify using this approach. In this study, we reviewed 47 high-grade neoplasms originally diagnosed as pancreatic neuroendocrine neoplasms. In addition to the currently recommended stains, we performed capture-based sequencing of approximately 500 cancer genes and immunohistochemistry for p16 and trypsin or chymotrypsin. Using an integrated molecular and clinicopathologic approach, 42 (89%) of 47 cases had a clear final diagnosis of either G3 PanNET (n = 17), PanNEC (n = 17), or mixed acinar-NEC (n = 8). The 17 G3 PanNETs demonstrated frequent alterations in MEN1 (71%), DAXX (47%), ATRX (24%), TSC2 (35%), SETD2 (42%), and CDKN2A (41%). Contrary to prior reports, TP53 alterations were also common in G3 PanNETs (35%) but were always mutually exclusive with CDKN2A alterations in this group. The 17 PanNECs demonstrated frequent alterations in TP53 (88%), cell cycle genes RB1 (47%), CCNE1/CCND1 (12%), CDKN2A (29%), and in KRAS (53%) and SMAD4 (41%); TP53 was coaltered with a cell cycle gene in 76% of PanNECs. Diffuse strong p16 staining was observed in 69% of PanNECs in contrast to 0% of G3 PanNETs. The 8 acinar-NECs had recurrent alterations in ATM (25%), APC (25%), and STK11 (25%). Five cases remained difficult to classify, 3 of which exhibited overlapping molecular features with alterations in MEN1 with or without ATRX, and RB1 with or without TP53, making it unclear whether to classify as PanNET or PanNEC. Our data demonstrate that molecular profiling and immunohistochemistry for p16 greatly improve the diagnostic accuracy of high-grade pancreatic neuroendocrine neoplasms and identify a subset of rare cases with overlapping features of both PanNET and PanNEC.

Pigmented perivascular epithelioid cell tumor of the skin: first case report.

The authors present a first case of pigmented perivascular epithelioid cell tumor (PEComa) of the skin, which was misdiagnosed histopathologically as metastatic melanoma. PEComa are exceedingly rare neoplasms, and only a few cases have been reported in kidney, liver, and pelvis. Herein, we describe this very rare entity in the subcutaneous tissue of the flank with very similar if not identical morphology of renal clear cell carcinoma. Because of the presence of focal melanin pigmentation and strong positivity for HMB-45, the lesion was mistaken for metastatic melanoma. To the best of authors' knowledge, this is the first case of cutaneous PEComa with melanin pigmentation. Awareness about occurrence of the lesion in the subcutaneous tissue and its unique immunoprofile would be helpful to reach correct diagnosis and to distinguish this lesion from melanoma or metastatic renal clear cell carcinoma.

Tubulocystic Carcinoma of Bile Ducts: A Distinct Type of Cholangiocarcinoma Associated With Adenofibroma-type Lesions.

A type of cholangiocarcinoma (CCA) characterized by peculiar histologic patterns and underlying adenofibromatous lesions has been reported in the literature mostly as individual case reports. This study aims to further clarify the defining characteristics of this spectrum of lesions. Clinicopathologic analysis of 8 biliary tumors with tubulocystic architecture arising in the background of adenofibroma-type lesions was performed. Three of these were also investigated with next-generation sequencing with a 174 genes panel. The patients were 5 males and 3 females, with a mean age of 64.6. All tumors were intrahepatic except for one perihilar that protruded into soft tissues. The mean size was 4.4 cm. At histology, all cases showed a peculiar and cytologically bland tubulocystic pattern that closely resembled tubulocystic-type kidney cancers, including back-to-back microcystic units that formed relatively demarcated nodules, and occurring in the background of adenofibromatous lesions. One case showed perineural invasion by otherwise deceptively benign-appearing microcystic structures, one had areas transitioning to intraductal tubulopapillary neoplasm, and 3 cases harbored more conventional small-duct CCA foci. In those 3 cases, both the tubulocystic and conventional CCA components were investigated by next-generation sequencing separately, and they shared the molecular alterations, including recurrent mutations in chromatin remodeling genes, such as ARID1A , BAP1 , and PBRM1 , and the actionable FGFR2-MCU fusion gene. In the limited follow-up, all but one were alive and free of disease after surgical resection. In conclusion, we described a distinct entity of CCA with specific histo-molecular features, for which we propose the designation of tubulocystic carcinoma of bile ducts.

Tuberous sclerosis complex mutations in patients with pancreatic neuroendocrine tumors. Observations on phenotypic and treatment-related associations.

Pancreatic neuroendocrine tumors (PanNETs) in familial tuberous sclerosis (TSC1 and TSC2 mutations) have been known and studied. However, little is known about PanNET patients harboring the very rare (less than 2%) sporadic TSC mutations. Some renal tumors have been shown to harbor sporadic TSC mutations, with a distinctive morphological correlate. We hereby describe this rather unusual molecular alteration in well-differentiated pancreatic neuroendocrine tumors (WD PanNETs) with a focus on their morphology and treatment outcomes. Six cases of WD PanNETs harboring sporadic TSC mutations were identified retrospectively. H&E slides and corresponding immunostains were reviewed for all cases. Clinical, molecular, and radiological information was obtained using the electronic medical records. Cohort consisted of 4 males and 2 females. Median age at diagnosis was 50 years (range 33-74 years). Origin of neoplasm was the pancreas and, in all but one, patient had liver metastasis by the time of presentation. Six out of six cases demonstrated a unique tumor morphology, with ample eosinophilic cytoplasm. Tumors were arranged in sheets and nests; prominent cystic change was noted in one case. Two cases were additionally biopsied post-treatment with capecitabine and temozolomide, and showed even more abundant oncocytic cytoplasm, eccentric nuclei, and a prominent cherry red nucleolus, and were arranged in a cluster of 3-4 cells, separated by stromal cells. Every patient had a different TSC2 variant with no cases of TSC1 mutations. Other common variants included MEN1 (4/6), DAXX (2/6), and TP53 (2/6). Per the WH0 2019 classification, tumors were graded as NET-G3 (n = 3) and NET-G2 (n = 3). Ki-67 s ranged from 7.2 to 60. All cases had retained MMR protein expression. The majority of patients (4/6) have expired. Although they received multiple treatments, a consistent pattern observed in patients was marked radiologic response to chemotherapy with capecitabine and temozolomide (offered in 5/6 patients) with duration of responses reaching 11 months in the majority of cases, with one patient showing near complete pathologic response of localized disease. TSC2 mutations may confer distinctive appearance in WD PanNETs, reminiscent of their effects in renal tumors. Although not entirely specific, this distinct morphological pattern with abundant eosinophilic cytoplasm in WD PanNETs could be reflective of an associated TSC mutation, with suggestions of significant therapeutic response to a specific cytotoxic chemotherapy.

Ciliated foregut cysts involving the hepatopancreaticobiliary system: a clinicopathological evaluation with focus on atypical features.

AIMS: Foregut cystic malformations are rare developmental abnormalities, which may involve the hepatopancreaticobiliary tract (HPBT). These cysts are composed of inner ciliated epithelium; subepithelial connective tissue layer; smooth muscle layer; and an outer fibrous layer. While radiopathologic findings are often diagnostic, atypical location and histologic features can pose a diagnostic challenge. We aimed to study ciliated foregut cysts (CFCs) in the HPBT, assess their clinicopathological features with a focus on atypical features. METHODS: We collected cases of CFCs involving the HPBT from three large academic medical centres. H&E-stained slides and immunohistochemical stains (where available) were reviewed for each case. Relevant demographic, clinical and pathological information was collected from the medical records. RESULTS: 21 cases were identified. The median age was 53 years (range, 3-78 years). 17 cysts were identified within the liver (segment 4 was the most common location, n=10) and 4 in the pancreas. Cysts were mostly identified incidentally (n=13), abdominal pain was a common symptom (n=5). Cyst size ranged from 0.7 to 17.0 cm (median, 2.5 cm). Radiological findings were available in 17 cases. Cilia were identified in all cases. 19 of 21 cases demonstrated the presence of a smooth muscle layer (thickness, <0.1 mm to 3.0 mm). Three cases showed gastric metaplasia, while one case revealed additional low-grade dysplasia, with features similar to intraductal papillary neoplasm of the bile duct. CONCLUSIONS: We highlight clinicopathological features of CFCs in the HPBT. The histomorphology is usually straightforward; however, unusual location and atypical features can pose a diagnostic challenge.

Peripheral nodular enhancement in adrenal and renal hematomas: A report of 3 cases.

There are a wide range of benign and malignant pathologies that the radiologist may encounter in the adrenal glands and kidneys, often incidentally when imaging is performed for other indications. Many imaging modalities including CT, MR, and US are often used in an attempt to characterize these lesions. A definitive radiological diagnosis, however, is not always possible. This is at times due to atypical presentations of typical lesions which may be mistaken for more aggressive or concerning pathologic conditions. Adrenal lesions that do not demonstrate characteristic benign imaging features might require surgical excision. Similarly, cystic renal lesions that demonstrate nodular enhancement are concerning for Bosniak IV lesions and require surgical management. We report 3 cases in 3 different patients of incidentally discovered hematomas with peripheral enhancement, 2 involving the adrenal gland and 1 involving the kidney. All 3 of these histologically proven hematomas demonstrated similar radiological manifestations of peripheral nodular progressive enhancement, mimicking neoplastic conditions, and necessitating surgical removal.

Pulse/hyaline ring granuloma revisited: etiologic role of seed-derived storage cells.

The objectives are to precisely identify the cells that incite the formation of lesions that are generally known as "pulse granuloma" or "hyaline ring granuloma" that occur mostly in the oral cavity, in the lungs, in and around the gastrointestinal tract, and other sites, and to suggest an alternative name for these lesions that accurately reflects their etiology. Critical review of the medical and dental literature was undertaken, and the microscopic appearances of granuloma-inciting cells depicted in the literature and seen in our practices were compared with seeds and their contents originating from a variety of leguminous and non-leguminous plants. Sections of selected seeds were examined microscopically before and after digestion with saliva and alpha amylase and subsequent routine processing and staining with H&E, PAS, and iodine. Pre- and post-digestion slides were examined with polarized light. The morphology of the granuloma-inciting cells is identical to the storage cells present in seeds from a variety of leguminous and non-leguminous plants. The cells that trigger the formation of "pulse granulomas"/"hyaline ring granulomas" are storage cells that are derived from ingested seeds of leguminous and non-leguminous plants. The terms "pulse," "legume," and "lentil," which have been applied to these cells, are misnomers. Our findings indicate that the terms "pulse granuloma" and "hyaline ring granuloma" are not appropriate descriptors of these lesions. We recommend that they be replaced by "seed storage cell granuloma," a term that now accurately reflects the etiology of these lesions.

Preliminary experience with a new institutional tumor board dedicated to patients with neuroendocrine neoplasms.

PURPOSE: To determine the decision patterns of a neuroendocrine neoplasm (NEN) tumor board (TB) and the factors behind those. METHODS: We retrospectively reviewed all NEN-TB recommendations from 07/2018 to 12/2021 and recorded patient characteristics, TB outcomes and associations between them. RESULTS: A total of 652 patient entries were identified. Median age of participants was 61 years and an equal number of men and women were presented. Most patients (33.4%) had tumors originating in the small bowel with 16.8% of high grade and 25.9% of pancreatic origin. Imaging was reviewed 97.2% of the time, with most frequently reviewed modalities being PET (55.3%) and CT (44.3%). Imaging review determined that there was no disease progression 20.8% of the time and significant treatment changes were recommended in 36.1% of patients. Major pathology amendments occurred in 3.7% of cases and a clinical trial was identified in 2.6%. There was no association between patient or disease presentation with the tumor board outcomes. There was a slight decrease in number of patients discussed per session, from 10.0 to 8.2 (p < 0.001) when the TB transitioned to a virtual format during the COVID-19 pandemic but all other factors remained unchanged. CONCLUSION: NEN-TB relies heavily on image review, can impact significant treatment changes in patients with rare tumors like NENs, and was not affected by the switch to a virtual format. Finally, none of the examined factors were predictive of the tumor board recommendations.

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), granulation tissue-like (n=13), and mucosal prolapse-like (n=4) variants. These variants can be easily misdiagnosed or misinterpreted on routine examination if KS is not considered, and if the immunohistochemical stain for human herpesvirus-8 is not performed. The other 2 morphologic variants present as spindle cell proliferations and are the GI stromal tumor-like (n=8) and inflammatory myofibroblastic tumor-like (n=2). These variants raise a broad differential diagnosis of spindle cell tumors of the GI tract and could pose diagnostic challenges. In summary, GI KS lesions exhibit variable, often unconventional histomorphologic patterns. KS should be included in the differential diagnosis even if features of conventional KS are not seen, particularly in limited biopsies in immunocompromised patients, such as those with human immunodeficiency virus infection. Although the clinical significance of these morphologic variants is yet to be determined, they are nonetheless important from a diagnostic standpoint. Misdiagnosis and delay in appropriate management can be avoided by recognizing the morphologic diversity of GI KS and appropriately utilizing the human herpesvirus-8 immunohistochemical stain.

Histo-molecular characterization of pancreatic cancer with microsatellite instability: intra-tumor heterogeneity, B2M inactivation, and the importance of metastatic sites.

Pancreatic ductal adenocarcinoma (PDAC) with microsatellite instability (MSI)/defective mismatch repair (dMMR) is the only subtype of pancreatic cancer with potential response to immunotherapy. Here, we report the histo-molecular characterization of MSI/dMMR PDAC with immunohistochemistry, MSI-based PCR, and next-generation sequencing. Five paradigmatic cases have been identified. The main results include the first report in pancreatic cancer of MSI/dMMR intra-tumor heterogeneity, the presence of microsatellite-stable metastases from MSI/dMMR primary and recurrent B2M gene inactivation, which may confer resistance to immunotherapy. In addition to the classic PDAC drivers, ARID1A was the most common mutated gene in the cohort. Intra-tumor heterogeneity, B2M inactivation, and metastatic sites should be carefully considered in MSI/dMMR PDAC, which should also be investigated in routine diagnostic practice with specific molecular analysis. The chromatin remodeler ARID1A represents another potential driver gene in this context.

Spatially restricted drivers and transitional cell populations cooperate with the microenvironment in untreated and chemo-resistant pancreatic cancer.

Pancreatic ductal adenocarcinoma is a lethal disease with limited treatment options and poor survival. We studied 83 spatial samples from 31 patients (11 treatment-naïve and 20 treated) using single-cell/nucleus RNA sequencing, bulk-proteogenomics, spatial transcriptomics and cellular imaging. Subpopulations of tumor cells exhibited signatures of proliferation, KRAS signaling, cell stress and epithelial-to-mesenchymal transition. Mapping mutations and copy number events distinguished tumor populations from normal and transitional cells, including acinar-to-ductal metaplasia and pancreatic intraepithelial neoplasia. Pathology-assisted deconvolution of spatial transcriptomic data identified tumor and transitional subpopulations with distinct histological features. We showed coordinated expression of TIGIT in exhausted and regulatory T cells and Nectin in tumor cells. Chemo-resistant samples contain a threefold enrichment of inflammatory cancer-associated fibroblasts that upregulate metallothioneins. Our study reveals a deeper understanding of the intricate substructure of pancreatic ductal adenocarcinoma tumors that could help improve therapy for patients with this disease.

Mild changes of hepatic nodular regenerative hyperplasia may cause portal hypertension and be visible on reticulin but not hematoxylin and eosin staining.

Nodular regenerative hyperplasia (NRH) can manifest as alternating parenchymal compression/expansion on hematoxylin and eosin (H&E) staining and as reticulin collapse/nodularity on reticulin staining. Histologic diagnosis can be challenging, especially when there is mild disease and on limited biopsy samples. We reviewed clinical and histologic parameters in a large series of NRH. We identified 60 liver specimens convincingly showing changes of NRH and reviewed them for clinical (age, sex, symptoms, lab values, portal hypertension [PHTN], NRH etiology) and histologic (inflammation, sinusoidal dilation, cholestasis, architectural change, portal vascular abnormalities, degree of changes on reticulin) parameters. The cases came from 28 women and 32 men (median age: 54 years). Most (55, 92%) were biopsies. Thirty patients were symptomatic. Forty-five cases showed mild NRH changes on reticulin; 24 of these (53%) showed them on H&E as well. Fifteen demonstrated well-developed changes on reticulin, which were always seen on H&E as well. Sinusoidal dilation was commonly observed in both of these subgroups (88% overall). Portal vascular abnormalities were seen in 33%. Well-developed NRH was diffuse more often than mild NRH (53% vs. 4%, P < 0.0001). Twenty-nine patients had clinically confirmed or likely PHTN. Of these, 21 showed mild and 8 showed well-developed NRH changes; only 3 had concomitant advanced fibrosis. Chemotherapy was the most frequent known cause of NRH; 30 patients lacked any definite etiology. NRH can be difficult to diagnose on biopsy, particularly since mild changes may be visible on reticulin but not H&E; even these patients can have PHTN. Additionally, NRH is often idiopathic, potentially lowering clinical and pathologic suspicion. Pathologists should have a low threshold for ordering reticulin stains, especially when a patient is known to have PHTN. Sinusoidal dilation, while nonspecific, commonly accompanies NRH.

Incidental secondary findings in hemorrhoidectomy specimens: a 16-year experience from a single academic center.

Hemorrhoidectomy specimens serve as an excellent resource for study of incidental anal pathology. Detection of most incidental findings is quite rare, although diagnosing clinically significant lesions can have profound impact on the clinical follow-ups. While there are many case reports of incidental findings in hemorrhoidectomy specimens, there are few large studies focused on this topic. The aim of this study was to describe the spectrum and likelihood of detecting incidental findings in hemorrhoidectomy specimens. We reviewed all hemorrhoidectomy specimens that showed incidental clinically significant diagnoses over a 16-year period (2003-2019) for this study. Patient's age, sex, and significant clinical history (Human Immunodeficiency Virus (HIV) status, precursor lesions, other malignancy) were recorded from clinical notes. We identified incidental clinically significant findings in 72 of 1612 (4.5%) specimens. We identified 7 incidental malignancies (squamous cell carcinoma, verrucous carcinoma, adenocarcinoma, mixed adenocarcinoma and neuroendocrine carcinoma, poorly differentiated neuroendocrine carcinoma, melanoma), 54 anal intraepithelial neoplasias (AINs), and 11 benign findings (melanocytic lesions, colorectal polyps, angiokeratoma, infectious/inflammatory). Within the AIN group, the detection of low-grade squamous intraepithelial lesions (LSILs) remained steady; there was a recent, sustained rise in detection of high-grade squamous intraepithelial lesions (HSILs), with more cases showing HSILs (2.6%) than only LSILs (0.7%). In 72.2% of patients, the incidental secondary finding represented a first diagnosis for that entity in the anal canal. Thirty seven percent of patients with anal dysplasia in the hemorrhoidectomy specimen had a prior diagnosis of squamous dysplasia in the anogenital tract. Overall, significant incidental findings were detected in 4.5% (72/1612) of hemorrhoidectomies, supporting routine histological examination of these specimens.

Human Papillomavirus (HPV) Detection by Chromogenic In Situ Hybridization (CISH) and p16 Immunohistochemistry (IHC) in Breast Intraductal Papilloma and Breast Carcinoma.

PURPOSE: This study explored human papillomavirus (HPV) amplification in breast benign and malignant lesions by chromogenic in situ hybridization (CISH) and the concordance of p16 expression by immunohistochemistry. PATIENTS AND METHODS: The presence of HPV6/11 and HPV16/18 in 33 cases of intraductal papilloma, 34 cases of ductal carcinoma in situ (DCIS), and 56 cases of invasive breast carcinoma (IBC) was evaluated using matched-background breast parenchyma and breast reduction as control groups. Association with clinicopathologic factors including prognosis was assessed. RESULTS: HPV 6/11 was observed in 0 cases (0%) of breast reduction, one case (3%) of intraductal papilloma, 11 cases (32.4%) of DCIS, and eight cases (14.3%) of IBC. HPV 16/18 was detected in three cases of (9.1%) breast reduction, six cases (18.8%) of intraductal papillomas, 14 cases (41.2%) of DCIS, and 25 cases (44.6%) of IBC. There was no difference in the HPV status between intraductal papilloma and breast reduction. HPV amplification in intraductal papilloma did not associate with developing atypia or carcinoma after long-term follow-up. However, HPV 6/11 and HPV 16/18 amplification was significantly higher in both DCIS and IBC when compared with breast reduction (P < .05). Compared with background breast parenchyma, HPV 16/18 amplification was significantly higher in both DCIS and IBC (P = .003 and P = .013, respectively). No correlation between p16 immunohistochemical staining and either of the HPV CISH testing was found (P > .05). CONCLUSION: HPV infection was detected in both breast lesions and background parenchyma. HPV infection may play a role in the pathogenesis of breast cancer but is not associated with intraductal papilloma. Immunohistochemical stain for p16 is not a good surrogate marker for HPV infection in breast lesions.

Ciliated HPV-Related Carcinoma: A Diagnostic Challenge on Frozen Section.

Oropharyngeal squamous cell carcinomas associated with high risk HPV show a wide morphological spectrum, including papillary, adenosquamous, lymphoepithelioma-like and sarcomatoid. We report an interesting case of ciliated HPV-related carcinoma arising from tonsillar tissue in a 55-year-old man which was associated with HPV33. This rare variant has been described in only a handful of cases in the literature, and to our knowledge this is the first case specifically associated with HPV33. The presence of cilia is a potential diagnostic problem as it has been traditionally considered a feature of benignancy, and could pose a particular challenge on frozen section. The diagnostic challenges, differential diagnosis of this tumor and the association with HPV33 are discussed.

Evaluation of Biomarkers in Multiple Ipsilateral Synchronous Invasive Breast Carcinomas.

CONTEXT.­: The College of American Pathologists guidelines recommend testing additional tumor foci in multifocal invasive breast carcinomas for the biomarkers estrogen receptor (ER), progesterone receptor, and HER2 only if the carcinomas show different morphologies or grades. OBJECTIVE.­: To assess clinical significance of testing for biomarkers in additional tumor foci in multifocal invasive breast tumors. DESIGN.­: Retrospective analysis of 118 patients diagnosed with ipsilateral synchronous multifocal breast carcinomas from January 2015 through March 2016 at Mount Sinai Hospital (New York, New York). RESULTS.­: Eighty-six cases were tested for at least 1 of the 3 biomarkers in additional tumor foci. Fifteen cases (17%) showed discordant staining between the 2 foci for at least one biomarker. Of the 7 of 67 ER-discordant cases (10%), 4 (57%) showed major variation from negative to positive expression, including 3 cases in which a smaller tumor focus was strongly positive for ER whereas the index tumor was negative. Similarly, within the 7 of 67 progesterone receptor-discordant cases (10%), 4 (57%) showed major variation from negative to positive, and in 3 cases with major discordance, the index tumor was negative for progesterone receptor, whereas a smaller focus was positive. A difference in HER2 expression was noted in 5 of 86 cases (6%). In only 5 of the 15 patients (33%) with discordant results, biomarker testing on additional foci would have been offered per the College of American Pathologists recommendations because of differences in histology or grading. Of the remaining 10 patients, 7 (70%) with positive results on smaller foci would have been deprived of appropriate adjuvant systemic treatment if the smaller focus had not been tested. CONCLUSIONS.­: We propose that negative values expressed in the primary tumor be repeated routinely on additional ipsilateral synchronous tumors.

Mucoepidermoid carcinoma of the oropharynx: a tumor type with a propensity for regional metastasis unrelated to histologic grade.

The designation "mucoepidermoid tumor" is a historic one used in reference to a form of mucoepidermoid carcinoma (MEC) that was believed to be benign. This bygone notion was based on the observation that the vast majority of MECs arising from the intraoral minor salivary glands behave in a benign fashion, particularly when they do not exhibit high grade features. There has been a recent move to partition the oral vault into the oral cavity proper and the oropharynx based on awareness that these compartments are distinct, and that similar tumor types arising from these compartments may behave in dramatically different ways (e.g, oral cavity squamous cell carcinoma vs oropharyngeal squamous cell carcinoma). The pathology databases from 3 large academic medical centers were searched for cases of MECs arising in the oropharynx. Relevant clinical and pathological information was collected from the medical records. Twenty-five cases were identified. They were from 18 females (72%) and 7 males (28%), ranging in age from 31 to 88 years (median, 61). Twenty-two (88%) were classified as low (n = 12) or intermediate (n = 10) grade, and 3 (12%) as high grade. Most arose from the base of tongue (n = 24), but one arose from the lateral pharyngeal wall. The median tumor size was 2.0 cm. Nineteen patients underwent neck node dissections. Of these, 13 (68%) had histologically documented lymph node metastases. MECs that lacked high grade features were almost as likely to metastasize as those with high grade features (50% vs 66%, Fisher exact = 1). Of 3 metastases tested, 2 harbored the MAML2 gene fusion. MECs arising from the base of tongue are associated with an alarmingly high rate of nodal metastases. This behavior cannot be predicted by histologic grading or MAML2 status. The propensity to metastasize may to some degree reflect the unique microenvironment of the oropharynx.