[2022 WHO classification of renal cell carcinomas: Focus on papillary renal cell carcinoma]. / Classification OMS 2022 des cancers du rein : focus sur le carcinome rénal papillaire.

Renal cell carcinomas (RCC) represent a group of heterogeneous tumors whose classification has greatly evolved since 1981. The latest update in 2022 classifies all renal cell carcinomas into six categories according to their morphology or the detection of specific molecular alterations. Molecular disassembly of renal cell carcinomas with papillary features has enabled the identification of new entities characterized by a specific molecular alteration, such as Fumarate Hydratase (FH) deficient RCC, TFE3-rearranged RCC or TFEB-altered RCC. This new classification allows for a more accurate diagnosis but requires a thorough knowledge of the genomic alterations to search for with immunohistochemical or molecular biology techniques. According to the new WHO 2022 classification, papillary renal cell carcinoma (PRC) type 1 or type 2 classification is no longer recommended. A classification based on nucleolar ISUP grade must be preferred: low-grade PRC (ISUP 1-2) or high-grade PRC (ISUP 3-4). The other prognostic factors remain the same: the pTNM stage, lymphovascular invasion, and the presence or absence of dedifferentiated areas referring to sarcomatoid or rhabdoid features. Of note, the presence of necrosis is not currently recognized as a poor prognostic element for this type of carcinoma. The diagnosis of high-grade PRC is from now on a diagnosis of exclusion. It can only be sustained after having ruled out TFE3-rearranged RCC, TFEB-altered RCC, and FH-deficient RCC. For clinicians, the diagnosis of PRC implies suggesting an oncogenetic consultation to screen for an associated genetic tumor syndrome regardless of the patient's age.

Solid Papillary Carcinoma and Encapsulated Papillary Carcinoma of the Breast: Clinical-Pathologic Features and Basement Membrane Studies of 50 Cases.

INTRODUCTION: Solid papillary carcinoma (SPC) and encapsulated papillary carcinoma (EPC) of the breast are usually considered in situ lesions due to favorable prognosis, despite the variable presence of myoepithelial cells. We aimed to describe clinical-pathologic features including basement membrane (BM) studies in these tumors. METHODS: Patients diagnosed with SPC and EPC in 2000-2019 were retrospectively identified. Microscopic slides and clinical history were reviewed. Immunohistochemical stains for BM and myoepithelial markers were performed. RESULTS: Of 23 SPCs and 27 EPCs, there were 5/23 (21.7%) pure SPCs and 9/27 (33.3%) pure EPCs, while 4/23 (17.4%) and 12/27 (44.5%) were associated with ductal carcinoma in situ (DCIS), and 6/23 (26.1%) and 6/27 (22.2%) with invasive carcinoma, respectively; 8/23 (34.8%) SPCs were considered invasive. The median tumor size was 1.7 cm (range 0.1-16). All tumors were positive for hormone receptors and negative for HER2. Myoepithelial cells were absent in 20 tumors (40%) and focally present in 30 (60%). Collagen IV and laminin were negative in most invasive lesions, but they were expressed in 21/21 (100%) and 18/21 (85.7%) of EPCs without invasion, and 16/17 (94.1%) and 10/17 (58.8%) SPCs, including invasive SPCs, respectively. Lymph node involvement was identified in 3/26 (11.5%) patients, including micrometastasis in 1 EPC associated with DCIS, macrometastasis in 1 EPC associated with invasive carcinoma, and isolated tumor cells in 1 invasive SPC. Of 31 patients with outcome data (median follow-up 35 months, range 1-85), 2 (6.5%; 1 SPC, 1 EPC) developed local recurrence, both associated with invasive carcinoma. No distant recurrences or deaths were observed. CONCLUSIONS: Our study confirms favorable prognosis of SPCs and EPCs, with 2 local recurrences occurring in the presence of invasion. SPCs are more commonly associated with invasive carcinoma or considered invasive compared to EPCs (60.9 vs. 22.2%). The presence of BM material and lack of lymph node involvement in most cases indicates that the majority of these tumors may represent in situ lesions; however, some may behave as low-grade invasive malignancy with metastatic potential even in the absence of conventional invasion.

Is papillary thyroid microcarcinoma a biologically different disease? A propensity score-matched analysis.

BACKGROUND: Papillary thyroid microcarcinoma exhibits an indolent clinical course and could be a candidate for active surveillance in the appropriate setting. It remains unknown whether papillary microcarcinoma is biologically different from larger papillary carcinoma >1 cm. METHODS: We analyzed clinicopathological information and transcriptome data of papillary thyroid cancer samples from The Cancer Genome Atlas. Propensity-score matching was used to construct a matched cohort consisting of 29 microcarcinomas and 58 carcinomas. Principal component analysis and unsupervised hierarchical cluster analysis were carried out to investigate the similarity of gene expression profiles. RESULTS: After adjustment for differences in baseline clinicopathological and genetic factors, transcriptome could be grouped mainly on the basis of tumor class (BRAF-like vs RAS-like) and tumor size (microcarcinoma vs carcinoma). The gene set enrichment analysis showed that extracellular matrix-associated pathways were enriched in the MSigDB database. CONCLUSION: Papillary thyroid microcarcinomas display a distinct gene expression pattern different from the corresponding carcinomas. We hypothesize that tumor microenvironment may play a role in the microcarcinoma/carcinoma phenotypic divergence.

Breast Tumours Resembling the Tall Cell Variant of Thyroid Papillary Carcinoma: Are They Part of the Papillary Carcinoma Spectrum or a Distinct Entity?

BACKGROUND: Papillary tumours of the breast are diagnostically challenging lesions and represent a wide spectrum of diseases from papilloma to invasive papillary carcinoma. A rare subtype of breast papillary tumour resembling the tall cell variant of thyroid papillary carcinoma (BTRTPC) has been described. The nomenclature of this entity, its relationship to other papillary tumours, and its nature, whether in situ or invasive, remain unclear. METHODS: Seventy-five papillary carcinomas (PCs) of the breast previously diagnosed in routine practice were reviewed and the presence of features (n = 10) characteristic of BTRTPC were assessed to determine whether BTRTPC comprises a distinct entity or is part of the spectrum of the previously defined PC variants. RESULTS: Nuclear overlapping and eosinophilic granular cytoplasm were seen in 81 and 75% of the cases, whereas nuclear grooves, nuclear clearing, and tall cells were noticed in 51, 42, and 38% of the cases, respectively; 27% of the cases showed macro- and micro-follicular architecture filled with colloid-like material. Five cases (7%) lacked oestrogen receptor (ER) expression. Co-existing invasive carcinoma was seen in 25 cases (33%). Two cases displayed several features characteristic of BTRTPC, and both were ER-negative. CONCLUSION: Features characteristic of BTRTPC overlap with other PCs of the breast. Molecular and immunohistochemical biomarkers are needed to provide objective diagnostic criteria for the characterisation of such lesions in routine practice.

AJCC 7th edition staging classification is more applicable than AJCC 8th edition staging classification for invasive IPMN.

BACKGROUND: Both the 7th and 8th editions of the American Joint Committee on Cancer (AJCC) staging systems have been introduced for pancreatic adenocarcinoma. However, the applicability of these classifications for invasive intraductal papillary mucinous neoplasms (IPMN) has not been systematically examined. METHODS: Patients with invasive IPMN were retrieved from a cohort of 18 geographical sites (1973-2014 varying) in the Surveillance, Epidemiology, and End Results (SEER) cancer registry. The 7th and 8th editions of the AJCC staging were compared. Survival rates and multivariate analyses were computed. RESULTS: In total, 1216 patients with resected invasive IPMN were included. A major difference between the 7th and 8th systems is the definition of stage IIA (7th, beyond the pancreas without involvement of major arteries; 8th, maximum tumor diameter > 4 cm). The hazard ratio (HR) of stage IIA disease (versus stage IA, HR = 2.33, P < 0.001) was higher than that of stage IB disease (HR = 1.48, P = 0.087) by the 7th edition classification, whereas the HR of stage IIA disease (HR = 1.26, P = 0.232) was even lower than that of stage IB disease (HR = 1.48, P = 0.040) by the 8th edition classification. In addition, for the 8th edition staging system, tumor size was not a predictor of survival in patients with resectable tumor > 2 cm (size > 4 cm versus > 2 ≤ 4 cm, HR = 0.91, P = 0.420). CONCLUSIONS: The AJCC 7th edition staging classification is more applicable than the 8th edition classification for invasive IPMN.

Molecular genotyping of the non-invasive encapsulated follicular variant of papillary thyroid carcinoma.

AIMS: The non-invasive encapsulated follicular variant of papillary thyroid carcinoma (FVPTC) has been managed as a low-risk malignancy. Recently, a proposal was made to reclassify this tumour type as a premalignant lesion and rename it non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). This study aims to provide the first comprehensive study on molecular genotype-phenotype correlations of encapsulated FVPTC. METHODS AND RESULTS: This study was performed on 177 consecutive FVPTCs from January 2014 to April 2016. These were classified as non-invasive encapsulated FVPTC (n = 74) invasive encapsulated FVPTC (n = 51), and infiltrative FVPTC (n = 52), according to standard criteria, by two independent pathologists. Genetic alterations and other clinicopathological information were compared. BRAFV600E was found in 12.2% (non-invasive) and 11.8% (invasive) of encapsulated FVPTCs, and in 34.6% of infiltrative FVPTCs (P = 0.001). Mutation in encapsulated FVPTCs was limited to cases with rare or abortive papillae. RET-PTC1 and RET-PTC3 rearrangements were present (11.5%) only in infiltrative FVPTCs. In contrast, NRAS, HRAS and KRAS mutations were observed more often in encapsulated FVPTCs (48.6% in non-invasive and 66.7% in invasive) than in infiltrative FVPTCs (15.4%) (P < 0.001). Preoperative cytological examination did not distinguish between non-invasive and invasive encapsulated FVPTCs, whereas infiltrative FVPTC was more likely to be Bethesda class V/VI than the encapsulated type (60.4% versus 38.1%; P = 0.01). CONCLUSIONS: There were no differences in clinicopathological or molecular profiles between non-invasive and invasive encapsulated FVPTCs, except in vascular and capsular invasion. Therefore, the diagnosis of NIFTP, like that of follicular adenoma, may require surgical resection and exclusion of those tumours with any papillae.

Aggressive Variants of Papillary Thyroid Carcinoma: Hobnail, Tall Cell, Columnar, and Solid.

Papillary thyroid carcinomas are the most common endocrine cancer and are usually associated with good survival. However, some variants of papillary thyroid carcinomas may behave more aggressively than classic papillary thyroid carcinomas. The tall cell variant of papillary thyroid carcinoma is the most common aggressive variant of papillary thyroid carcinoma. The aggressive behavior has been ascribed to the histologic subtype and/or to the clinicopathologic features, an issue that remains controversial. The columnar variant of papillary thyroid carcinoma can be aggressive, particularly in older patients, with larger tumors showing a diffusely infiltrative growth pattern and extrathyroidal extension. A papillary thyroid carcinoma is designated as solid/trabecular variant when all or nearly all of a tumor not belonging to any of the other variants has a solid, trabecular, or nested (insular) appearance. This tumor must be distinguished from poorly differentiated thyroid carcinoma which has the same growth pattern but lacks nuclear features of papillary thyroid carcinoma and may show tumor necrosis and high mitotic activity. New to the fourth edition of the WHO Classification of Tumours of Endocrine Organs, the hobnail variant of papillary thyroid carcinoma is a moderately differentiated papillary thyroid carcinoma variant with aggressive clinical behavior and significant mortality. All of these variants are histologically unique and important to recognize due to their aggressive behavior.

Recent Advances in the Classification of Low-grade Papillary-like Thyroid Neoplasms and Aggressive Papillary Thyroid Carcinomas: Evolution of Diagnostic Criteria.

Papillary thyroid carcinomas account for ∼80% of well-differentiated thyroid tumors. During the past decade, several new variants of papillary-like thyroid neoplasms and papillary thyroid carcinomas have been recognized. Some of these neoplasms that were previously classified as malignant have been reclassified as low-grade neoplasms, as the diagnostic criteria have evolved. Similarly, some of the papillary thyroid carcinomas that were previously classified as conventional or classic papillary thyroid carcinomas have now been recognized as more aggressive variants of papillary thyroid carcinomas. Recognizing these differences becomes more important for the proper medical, surgical, and radiotherapeutic management of patients with these neoplasms.

Noninvasive encapsulated follicular variant of papillary thyroid carcinoma: Should it also be reclassified in children?

BACKGROUND: Noninvasive encapsulated follicular variant of papillary thyroid carcinoma (noniEFVPTC) has low risk of adverse outcome in adults, warranting reclassification as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). In children, thyroid nodules have higher risk of malignancy and it is unknown if encapsulated FVPTC (EFVPTC) and infiltrative FVPTC (IFVPTC) tumors have different behavior. We analyzed the clinicopathologic features of follicular variant of papillary thyroid carcinoma (FVPTC) subtypes in our pediatric population to determine if noniEFVPTC has an indolent course as reported in adults. PROCEDURE: We retrospectively studied all patients diagnosed with FVPTC at our institution. The clinicopathologic characteristics of the histologic subtypes were compared. RESULTS: Eighteen patients were identified, all treated with total thyroidectomy. No significant differences in age, sex, tumor size, focality, or prior malignancy were detected between subtypes. Extrathyroidal extension had significantly higher incidence in IFVPTC (5/8) compared with EFVPTC (1/10, P = 0.03), translating in significantly more T3 tumors within IFVPTC subtype (5/8), whereas most EFVPTC cases had T1 staging (6/10, T1 vs. T3, P = 0.05). EFVPTC had significantly lower rate of lymph node involvement (N1 in 2/8) compared with IFVPTC (N1 in 8/8, P = 0.003). Only one patient diagnosed with IFVPTC developed extranodal recurrence. When noniEFVPTC and iEFVPTC were separately compared, the noninvasive form showed no propensity for invasive growth (T3 staging: 0/4 vs. 2/6), lymph node metastasis (N1: 0/3 vs. 2/5) or extranodal recurrence. CONCLUSION: In children, noniEFVPTC/NIFTP has indolent behavior, warranting consideration of less aggressive management, similar to adults.

Clinical Safety of Renaming Encapsulated Follicular Variant of Papillary Thyroid Carcinoma: Is NIFTP Truly Benign?

BACKGROUND: Renaming encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) to noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was recently suggested to prevent the overtreatment, cost and stigma associated with this low-risk entity. The purpose of this study is to document the incidence and further assess the clinical outcomes of reclassifying EFVPTC to NIFTP. METHODS: We searched synoptic pathologic reports from a high-volume academic endocrine surgery hospital from 2004 to 2013. The standard of surgical pathology practice was based on complete submission of malignant thyroid nodules along with the nontumorous thyroid parenchyma. Rigid morphological criteria were used for the diagnosis of noninvasive EFVPTC, currently known as NIFTP. A retrospective chart review was conducted looking for evidence of malignant behavior. RESULTS: One hundred and two patients met the strict inclusion criteria of NIFTP. The incidence of NIFTP in our cohort was 2.1% of papillary thyroid cancer cases during the studied time period. Mean follow-up was 5.7 years (range 0-11). Five patients were identified with nodal metastasis and one patient with distant metastasis. Overall, six patients showed evidence of malignant behavior representing 6% of patients with NIFTP. CONCLUSION: Our study demonstrates that the incidence of NIFTP is significantly lower than previously thought. Furthermore, evidence of malignant behavior was seen in a significant number of NIFTP patients. Although the authors fully support the de-escalation of aggressive treatment for low-risk thyroid cancers, NIFTP behaves as a low-risk thyroid cancer rather than a benign entity and ongoing surveillance is warranted.

Warthin-like papillary thyroid carcinoma with immunoglobulin G4-positive plasma cells possibly related to Hashimoto's thyroiditis.

Hashimoto's thyroiditis with heavy lymphoplasmacytic infiltration is a common comorbidity of immunoglobulin G4 (IgG4)-related thyroiditis and Warthin-like papillary thyroid carcinoma (WL-PTC). We hypothesized that WL-PTC may have a strong association with IgG4-related thyroiditis. To validate this hypothesis, we clinically and immunohistochemically studied 17 WL-PTC cases. Fourteen patients (82.4%) had anti-thyroglobulin antibody and were confirmed to have Hashimoto's thyroiditis through microscopic analysis. Among them, five (29.4%) had disease consistent with IgG4-related thyroiditis but did not exhibit a "storiform" pattern or obliterative phlebitis. IgG4-related diseases were not found in other organs. No cases with serum IgG4 level of >135 mg/dL were noted. A total of 94.1% of WL-PTC cases had IgG4-positive plasma cells (+PCs) in the stroma, and cases with rich IgG4+PCs were more frequently associated with Hashimoto's thyroiditis than those with poor IgG4+PCs. In this study, all three cases without Hashimoto's thyroiditis had poor IgG4+PCs, and one of them did not exhibit IgG4+PCs in the stroma of WL-PTC and Hashimoto's thyroiditis. Nodal metastatic lesions were seen in eight cases, all of which were not WL-PTC. As such, we should consider that the Hashimoto's disease with rich IgG4+PCs seen in our cases is representative of non-IgG4-related disease and not IgG4-related disease involving multiple organs. This study is the first to demonstrate the presence of IgG4+PCs in the stroma of WL-PTC. We concluded that the appearance of IgG4+PCs in the stroma of WL-PTC may be related to Hashimoto's thyroiditis with rich IgG4+PC.

Cytoplasmic Lipid Accumulation Characteristic of the Cribriform Variant of Papillary Thyroid Carcinoma.

OBJECTIVE: The purpose of this study was to clarify the diagnostic significance of cytoplasmic lipid accumulation (CLIA) in the cribriform variant of papillary thyroid carcinoma (CV-PTC). METHODS: We performed a histological, immunohistochemical, and cytological examination of 35 CV-PTC cases at the Kuma Hospital. CLIA was defined as bubble-like multivacuolation in cytoplasm with distinct cell border. We also examined 100 conventional PTC (con-PTC) cases as controls. RESULTS: Histological analysis showed the presence of carcinoma cells with CLIA in 60.0% of CV-PTC and 5.0% of con-PTC cases. The vacuoles tended to distribute in the subnuclear portion of carcinoma cells showing papillary growth. They were positive for oil red O staining and adipophilin. The carcinoma cells without the vacuoles showed a subnuclear dot-like expression for adipophilin in CV-PTC cases, but not in the con-PTC cases. Cytological analysis showed CLIA in 17 (54.8%) of the 31 CV-PTC cases, but not in the con-PTC cases. CONCLUSION: This is the first study to report the presence of carcinoma cells with CLIA in CV-PTC. The subnuclear dot-like expression of adipophilin may be characteristic of CV-PTC. These findings might be related to degenerative changes occurring in CV-PTC.

SHOULD MULTIFOCAL PAPILLARY THYROID CARCINOMAS CLASSIFIED AS T1A WITH A TUMOR DIAMETER SUM OF 1 TO 2 CENTIMETERS BE RECLASSIFIED AS T1B?

OBJECTIVE: Considering the diameter of the largest tumor while determining T stage in multifocal papillary thyroid microcarcinomas (PTMCs) might cause underestimation of tumoral stage. We aimed to investigate the effect of total tumor diameter (TTD) on tumor node metastasis (TNM) classification in multifocal T1a PTMCs. METHODS: T1 tumors were grouped as T1a or T1b according to 7th TNM edition. For patients with multifocal T1a, TTD (the sum of the maximal diameter of each focus) was calculated, and these patients were further subgrouped as TTD ≤1 cm or TTD 1 to 2 cm. RESULTS: There were 724 patients with T1 tumors. Multifocality was observed in 150 (28.5%) of 527 patients with T1a and 84 (42.6%) of 197 patients with T1b tumors (P<.001). Lymph node metastasis (LNM), thyroid capsule invasion, and lymphovascular invasion were significantly higher in T1b compared to T1a (P<.001, P<.001, and P = .015, respectively). There were 8 (1.5%) patients with persistence but not any with recurrence in the T1a group. Persistence and recurrence were observed in 3 (1.5%) and 5 (2.5%) patients in the T1b group, respectively. Among 150 T1a patients with multifocal tumors, TTD was ≤1 cm in 89 (59.3%) and 1 to 2 cm in 61 (40.7%) patients. Number of tumor foci, LNM, and thyroid capsule invasion were significantly higher in multifocal T1a patients with TTD 1 to 2 cm compared to with TTD ≤1 cm (P<.001, P = .032, P = .014, respectively). CONCLUSION: TTD might be used as a parameter to determine patients at higher risk for persistence, and T1a multifocal PTMCs with TTD 1 to 2 cm can be reclassified as T1b. ABBREVIATIONS: ETE = extrathyroidal extension LNM = lymph node metastasis PTC = papillary thyroid carcinoma PTMC = papillary thyroid microcarcinoma RAI = radioactive iodine TNM = tumor, node, metastasis TTD = total tumor diameter.

Tall cell and diffuse sclerosing variants of papillary thyroid cancer: outcome and predicting value of risk stratification methods.

PURPOSE: Tall cell (TCV) and diffuse sclerosing (DSV) variants are aggressive variants of papillary thyroid cancer (PTC). We compared the risk of recurrent/persistent disease in patients with TCV, DSV and classical PTC (cPTC) and evaluated the prognostic accuracy of initial vs. ongoing risk stratification. METHODS: A consecutive series of DSV (n = 54), TCV (n = 72) and cPTC (n = 184) patients was retrospectively analyzed. TCV and DSV patients were first risk stratified for recurrent/persistent disease without considering the histotype as a risk factor and subsequently, 6-24 months after initial treatment, re-classified on the basis of the response to therapy (ongoing risk stratification). RESULTS: Extrathyroidal extension was more frequent in DSV than in TCV and cPTC patients (p < 0.05); moreover, only DSV tumors had a higher rate of recurrent/persistent disease when compared to cPTC treated with the same protocol (total thyroidectomy followed by 131I treatment) (p < 0.01). After initial treatment, 54.2% of TCV and 20.4% of DSV patients were classified at low risk, while at ongoing risk stratification, the excellent response (low risk) was higher for both TCV (77.8%) and DSV (50.0%) patients relative to initial stratification (both p < 0.01). Using ongoing risk classification, positive predictive value (PPV) for persistent/recurrent disease was higher relative to initial risk stratification for both TCV (PPV = 93.8 vs. 39.4%) and DSV (PPV = 63.0 vs. 34.9%), p < 0.05 for both. CONCLUSIONS: In our series DSV, but not TCV patients, had poorer outcome than cPTC treated with the same protocol. Moreover, the ongoing risk stratification predicted outcome better than the initial classification in both TCV and DSV patients.

The utility of the Bethesda category and its association with BRAF mutation in the prediction of papillary thyroid cancer stage.

PURPOSE: This study aims to determine the utility of the Bethesda category and its association with BRAF mutation in prediction of the papillary thyroid cancer (PTC) stage. METHODS: A prospective study analyzed patients who had ultrasound-suspicious thyroid nodules, underwent FNA and cytological examination, and were classified according to the Bethesda system. Patients from Undetermined Significance Or Follicular Lesion Of Undetermined Significance (AUS/FLUS), Follicular Neoplasm or Suspicious for a Follicular Neoplasm (FN/SFN), Suspicious for Malignant Cells (SMC), and Positive for Malignant Cells (PMC) groups were examined for the BRAF mutation and had a thyroid surgery. Demographical and histological features and stage of the disease were evaluated for PTC patients in accordance with the Bethesda category and its association with BRAF mutation. RESULTS: Three hundred eight of all patients underwent operation. One hundred forty-three (46.4%) of them were diagnosed with PTC. In 14 (9.8%) PTC cases, FNA biopsies were classified as AUS/FLUS, 23 (16.1%) as FN/SFN, 41 (28.7%) as SMC, and 65 (45.5%) as PMC. I-II stages of PTC were diagnosed for 88 (61.5%) patients and III-IVA for 55 (38.5%). Patients from the SMC and PMC groups had larger tumors, higher incidence of lymph node metastases, classical PTC type, B-type Raf (BRAF) positive, and III-IVA stage cancer, than patients from the AUS/FLUS and FN/SFN groups. When comparing 27 (18.9%) BRAF-negative patients from the AUS/FLUS and FN/SFN groups with 116 (81.1%) BRAF-negative patients from the SMC and PMC groups and all BRAF-positive patients, the prediction of more aggressive histological features and stage was slightly improved. CONCLUSIONS: Higher Bethesda categories are associated with higher stages of PTC. Association of the Bethesda category with BRAF mutation can slightly improve the value of stage prediction.

Papillary carcinoma of the breast: diagnostic agreement and management implications.

AIMS: Papillary carcinoma (PC), which is a rare type of breast cancer, comprises a heterogeneous group of tumours. The diagnostic categorization of PC as in-situ and invasive disease remains a matter of debate with respect to interpretation of its overlapping histological features, and with respect to the uncertainty in clinical behaviour that this dilemma raises. The aim of this study was to assess the diagnostic agreement regarding PC among reporting breast pathologists. METHODS AND RESULTS: Six cases of PC included in the UK National Health Service Breast Screening Programme breast pathology interpretive external quality assurance scheme in the last 10 years were reviewed. In this scheme, one representative haematoxylin and eosin-stained slide from each case is circulated to an average of 600 participants. Data on diagnostic categories were collected and slides were reviewed according to the World Health Organization (WHO) diagnostic criteria. The number of final diagnoses of malignancy (in situ or invasive) was highest for invasive PC (99% of the participants diagnosed it as malignant), followed by solid PC (94% and 95%, respectively), encapsulated PC (92% and 92%, respectively), and papillary ductal carcinoma in situ (DCIS) (88%). Most cases of papillary DCIS were correctly classified as in-situ disease (77%), but 28% of the participants classified invasive PC cases as in-situ disease. Of the participants, 24% reported encapsulated PC as invasive disease. Of the two solid PC cases, one showed some features consistent with the WHO description of invasive solid PC, whereas the other showed features of classic (non-invasive) solid PC. Both cases were reported as invasive by 75% and 77% of participants, respectively. Breast specialists more frequently classified PC as an in-situ carcinoma than did non-specialist participants, and the difference was significant (P = 0.013). CONCLUSIONS: Recognition of PC as a malignant entity (in situ or invasive) is high, but concordance of its classification into in-situ and invasive disease is low. Histological features that can define invasion in PC should be better defined. These rare lesions require additional diagnostic work-up, and difficult cases should trigger consensus opinion or expert referral.

Comparative clinicopathological study of biliary intraductal papillary neoplasms and papillary cholangiocarcinomas.

AIMS: The aim of this study was to achieve a better definition of intraductal papillary neoplasms of the bile duct (IPNBs). METHODS AND RESULTS: Biliary tumours that showed predominantly intraductal papillary growth were provisionally classified as IPNBs (n = 25) and papillary cholangiocarcinomas (n = 27). IPNB was defined as a neoplasm that is confined to the epithelium or is regularly arranged in a high-papillary architecture along thin fibrovascular stalks, whereas the term 'papillary cholangiocarcinoma' was used for tumours with more complex papillary structures (e.g. irregular papillary branching or mixed with solid-tubular growth). In our consecutive cohort of biliary neoplasms, 5% were classified as IPNBs, and 10% as papillary cholangiocarcinomas. IPNBs differed from papillary cholangiocarcinomas by less advanced invasion, gross mucin overproduction (72% versus 7%), and their prevalent location (84% of IPNBs in intrahepatic/hilar ducts; 70% of papillary cholangiocarcinomas in extrahepatic ducts). Gastric-type and oncocytic-type tumours were only detected in IPNBs. Expression of mucin core proteins and cytokeratin 20 significantly differed between the two groups. KRAS and GNAS were wild-type genotypes in all but one case of KRAS-mutated IPNB. Patients with IPNB had better recurrence-free survival than those with papillary cholangiocarcinoma (P = 0.007). In multivariate analysis, in which several other prognostic factors (e.g. stromal invasion and lymph node metastasis) were applied, the classification of the two papillary tumours was an independent prognostic factor (P = 0.040). CONCLUSIONS: Given the significant contrast in clinicopathological features between IPNBs and papillary cholangiocarcinomas, it may be more appropriate to use the diagnostic term 'IPNB' for selected tumours that show regular papillary growth, separately from papillary cholangiocarcinomas.

Is Invasive Micropapillary Serous Carcinoma a Low-grade Carcinoma?

"Invasive micropapillary serous carcinoma" has been proposed as a synonym for low-grade serous carcinoma by some expert pathologists. In contrast, Singer and colleagues reported that some serous carcinomas with conspicuous invasive micropapillary pattern (SC-IMPs) can show high-grade nuclear atypia. However, the molecular features of such tumors have not been well documented. The aim of this study was to demonstrate and emphasize the fact that high-grade serous carcinoma confirmed by immunohistochemistry and molecular analysis can show conspicuous invasive micropapillary pattern. We selected 24 "SC-IMPs" and investigated: (1) their morphologic features; (2) the immunostaining pattern of p53 protein; and (3) KRAS/BRAF/TP53 gene mutations. The 24 SC-IMPs were subdivided into low-grade and high-grade tumors based primarily on the nuclear atypia, with the mitotic rate used as a secondary feature: low grade (n=5) and high grade (n=19). Low-grade SC-IMPs were characterized by low-mitotic activity, absence of abnormal mitosis, presence of serous borderline tumor, occasional BRAF mutation, and infrequent TP53 mutation. High-grade SC-IMPs were characterized by high-mitotic activity, presence of abnormal mitosis, conventional high-grade serous carcinoma, frequent TP53 mutation, and lack of KRAS/BRAF mutation. We demonstrated that high-grade serous carcinoma confirmed by aberrant p53 immunostaining and molecular analysis can show conspicuous invasive micropapillary pattern, validating Singer and colleague's report. Serous carcinoma with conspicuous invasive micropapillary pattern should not be readily regarded as low-grade serous carcinoma. Nuclear grade is the most important diagnostic feature in the SC-IMPs.

Clear cell papillary renal cell carcinoma, renal angiomyoadenomatous tumor, and renal cell carcinoma with leiomyomatous stroma relationship of 3 types of renal tumors: a review.

Renal angiomyoadenomatous tumor has been described in 2000, followed by description of clear cell papillary renal cell carcinoma in 2006. Discussions about possible relationship of both tumors were published since their description. The main differential diagnostic feature was considered presence/absence of fibroleiomyomatous stroma-relationship of renal angiomyoadenomatous tumor in stroma-rich tumors. However, it was shown that stroma is reactive and nonneoplastic by its nature and that all other histologic, immunohistochemical, and molecular-genetic features of both entities are identical. In upcoming World Health Organization classification of renal tumors (2016), both lesions are considered as a single entity (clear cell papillary renal cell carcinoma [CCPRCC]). Most published cases followed the benign/indolent clinical course. In addition, most tumors has normal status of VHL gene (methylation, LOH 3p, mutations); however, CCPRCC was referred in patients with VHL syndrome. Another issue covered by this review is possible relationship of CCPRCC and "renal cell carcinoma with leiomyomatous stroma" (RCCLS). Renal cell carcinoma with leiomyomatous stroma shows clear cell cytology and abundant leiomyomatous stroma. Some of RCCLS are positive for cytokeratin 7; some are negative. Similar situation exists for relation of RCCLS and VHL gene abnormalities. It is so far unclear whether any relation between CCPRCC and RCCLS exists. From all published studies, it seems that these tumors are less likely related to each other.

[From new genetic and histological classifications to direct treatment]. / Carcinome urothélial : des classifications histologiques et moléculaires vers un traitement adéquat.

The most important criterion for optimal cancer treatment is a correct classification of the tumour. During the last three years, several very important progresses have been made with a better definition of urothelial carcinoma (UC), especially from a molecular point of view. We start having a global understanding of UC, although many details are still not completely understood.