POLE-Mutant Colon Adenocarcinoma-Case Presentation and Histopathological Evaluation.

INTRODUCTION: POLE mutant phenotype in colon adenocarcinomas represents a rare molecular subtype. These tumours are generally responsive to immune-checkpoint inhibition therapy and, therefore, are currently considered as a subtype with good prognosis. We hereby present the first detailed case presentation of a POLE mutant colon adenocarcinoma with useful microscopic features. CASE REPORT: A 53-year-old male patient's colon adenocarcinoma histologically showed wide variety of growth patterns and massive intra- and peritumoural lymphocytic infiltrate. The majority of the tumour consisted of a high-grade component resembling medullary carcinoma of the colon, while approximately one-third of the tumour was composed of conventional areas exhibiting a tubular pattern. A minority of the tumour was constituted by poorly cohesive rhabdoid cells. Immunohistochemistry was performed, and colorectal origin was proven with CDX-2 and SATB2. Furthermore, proficiency in mismatch repair proteins and SMARCB1 deficiency was observed. The unusually high-grade colon adenocarcinoma, with areas mimicking medullary carcinoma, and generally aggressive morphology raised suspicion of microsatellite instability. The diverse morphology and the SMARCB1 deficiency also raised suspicion of ultramutation caused by POLE alteration. Next-generation sequencing panel confirmed a pathogenetic mutation in POLE exon 9: p.Pro286Arg, c.857C > G. DISCUSSION: The diverse, high-grade morphology and increased intratumoural lymphoid infiltration should raise suspicion for POLE-mutated adenocarcinoma during everyday histopathological practice. Mismatch repair proficiency results on immunohistochemistry should not determine the final diagnosis, as only a minor percentage of these tumours are MSI. In every case suspicious for POLE-mutated adenocarcinoma, a 500-cancer gene panel should be carried out.

Primary follicular dendritic cell sarcoma of the kidney - a case report of a rare tumor with emphasis on diagnostic pitfalls.

BACKGROUND: Follicular dendritic cell sarcoma (FDCS) is a rare low-grade tumor of the lymph nodes, but roughly one-third of the cases emerge from extranodal sites, posing diagnostic challenges. CASE PRESENTATION: In this report, we present the case of a 59-year-old lady who complained of renal colic. During investigation, a kidney tumor was discovered. A radical nephrectomy was performed, and histological examination identified the tumor as a sarcomatoid renal cell carcinoma. The case was then referred to a genitourinary pathologist for further evaluation. The tumor cells exhibited positive staining for CD21, CD23, somatostatin receptor 2 A, and MDM2 expression. Additionally, MDM2 gene amplification was confirmed by the FISH study. Ultimately, the tumor was diagnosed as a primary renal FDCS. The patient was placed under active oncological surveillance and did not receive any further therapy. Remarkably, after 91 months of follow-up, she remains tumor-free. CONCLUSION: This case represents a well-documented primary renal FDCS. Our aim in presenting this extremely rare tumor is to enhance awareness and highlight the importance of considering FDCS in the differential diagnosis.

Molecular analysis of apocrine mixed tumors and cutaneous myoepitheliomas: a comparative study confirming a continuous spectrum of one entity with near-ubiquitous PLAG1 and rare mutually exclusive HMGA2 gene rearrangements.

Myoepithelial neoplasms of the skin and soft tissue still represent a confusing and somewhat controversial field in pathology as it appears that this category includes several different entities. However, recent studies have suggested that both apocrine mixed tumors (AMT) and cutaneous myoepitheliomas (CM) harbor identical chromosomal rearrangements involving the PLAG1 gene and hence may represent a morphological spectrum. The aim of the present study was to share our institutional experience with these tumors and specifically focus on studying their immunohistochemical and molecular features to further assess their relatedness. Eleven cases of AMT and 7 cases of CM were collected and analyzed using immunohistochemistry (IHC), PLAG1 FISH, and Archer FusionPlex assay. There were 14 male and 4 female patients with ages ranging from 26 to 85 years (median 55.8 years, mean 58.5 years). AMTs were mainly located in the head and neck (n = 10), while CMs were mainly located in the acral sites (n = 5). PLAG1 IHC was diffusely strongly positive in 14/17 (82%) cases, whereas a single case of AMT diffusely expressed HMGA2. Both tumor groups showed PLAG1 gene fusions which were detected in 6/13 analyzable samples (AMT, n = 4 and CM, n = 2), and included TRPS1::PLAG1 (n = 3), NDRG1::PLAG1 (n = 1), CTNNB1::PLAG1 (n = 1) and a novel PXDNL::PLAG1 fusion (n = 1). The remaining 5 cases were negative, 5 were not analyzable and the single case positive for HMGA2 by IHC revealed a potential HMGA2 gene rearrangement. The cases were further studied by FISH, with 12/17 cases showing PLAG1 gene rearrangement (AMT, n = 8 and CM, n = 4). Altogether, 14/18 cases showed PLAG1 gene rearrangement by at least one of the methods. PLAG1 immunohistochemistry had a 92% specificity and sensitivity. Our study provided additional data to suggest that AMT and CM share overlapping morphological and immunohistochemical features as well as molecular background characterized by PLAG1 gene fusions and thus represent a morphological spectrum. In addition, we identified a novel PXDNL::PLAG1 fusion and suggested that rare cases may harbor HMGA2 gene alterations which seem to be mutually exclusive with PLAG1 gene fusions. The relatedness of these tumors to salivary gland myoepithelial neoplasms and distinctness from eccrine mixed tumors and other skin and soft tissue myoepithelial neoplasms with EWSR1/FUS fusions is discussed.

TRPS1 expression in breast angiosarcoma.

Angiosarcoma (AS) of the breast, a rare mesenchymal neoplasm, exhibits distinct forms based on etiological and genetic features. While cases with typical clinical presentation and morphology allow for a straightforward diagnosis, challenges arise when clinical data are scarce, diagnostic material is limited, or morphological characteristics overlap with other tumors, including undifferentiated carcinomas. The trichorhinophalangeal syndrome protein 1 (TRPS1), once regarded as highly specific for breast carcinomas, now faces doubts regarding its reliability. This study explores TRPS1 expression in breast AS. Our investigation revealed that 60% of AS cases displayed TRPS1 labeling, contrasting with the 40% lacking expression. Scoring by four independent readers established a consensus, designating 12/35 ASs as unequivocally TRPS1-positive. However, uncertainty surrounded nine further cases due to a lack of reader agreement (being substantial as reflected by a kappa value of 0.76). These findings challenge the perceived specificity of TRPS1, shedding light on its presence in a noteworthy proportion of breast ASs. Consequently, the study underscores the importance of a comprehensive approach in evaluating breast ASs and expands the range of entities within the differential diagnosis associated with TRPS1 labeling.

[Myxoinflammatory fibroblastic sarcoma of the lower limb]. / Az alsó végtag myxoinflammatoricus fibroblastos sarcomája.

Myxoinflammatory fibroblastic sarcoma (MIFS) is a rare, low-grade, painless tumor of mesenchymal origin. In the current, 5th edition of the World Health Organisation (WHO) 'Classification of tumors: Soft tissue and bone tumors', there is no exact diagnostic genetic alteration defined in MIFS. Hereby we present the case of a 71-year-old female patient, with a medical history of benign essential hypertension, who visited the hospital because of a lesion above her right shin. She perceived the lesion 1.5 years prior to the medical attendance, and she only attended the medical facility because of the development of pain, erosion and papule formation on the skin surface. Microscopically, the lesion had cellular and pleomorphic appearance with nodular structure, and showed honeycomb-like infiltration of the subcutaneous fat tissue. Tumor cell infiltration was visible among the collagen fibers of the dermis. Tumor cells frequently displayed multinuclear morphology with prominent, viral inclusion-like nucleoli and exuberant fibrillary, often vacuolated and ground-glass cytoplasm. With immunohistochemical examination, tumor cells showed multifocal positivity with CD34, CD31, podoplanin (D2-40), cyclin D1, and epithelial membrane antigen (EMA). Furthermore, the tumor cells proved to be diffusely positive with smooth muscle actin (SMA). After meeting all the essential criteria of the current WHO classification, the case was concluded as MIFS, showing high-grade features. According to our experience, an immunohistochemistry panel of podoplanin, ciklin-D1, CD10, EMA, CD34, and CD31 can facilitate the correct conclusion. Our case of MIFS highlights the unusual, focally high-grade features of this complicated, challenging disease. Diffuse SMA positivity is a known, but uncommon feature of these tumors. Orv Hetil. 2023; 164(41): 1637-1641.

Cerebral manifestation and diagnostic dilemma of Rosai-Dorfman disease.

Rosai-Dorfman disease (RDD) is a rare, S100-positive histiocytic proliferation, that can cause both nodal and extranodal illness. We present a case of a 53-year-old male patient. Magnetic resonance imaging described a plaque-like meningeal lesion, and the preoperative diagnosis was meningioma. Histologically, dense infiltration of lymphocytes, plasma cells, and histiocytes was seen, furthermore, the presence of emperipolesis in the sample was pronounced. In the histiocytes nuclear and cytoplasmic positivity with S100 protein, and nuclear positivity with Cyclin D1 was observed. The case was concluded as RDD. Morphological appearance of intracranial RDD with imaging procedures can present a differential diagnostic challenge. The correct diagnosis is based on the presence of histiocytes with emperipolesis, and properly defined immunohistochemical characteristics.

Highlighting the immunohistochemical differences of malignant mesothelioma subtypes via case presentations.

Malignant mesothelioma (MM) is a rare tumor of mesothelial cells, with an increasing incidence both in developed and developing countries. MM has three major histological subtypes, in order of frequency, according to the World Health Organization (WHO) Classification of 2021: epithelioid, biphasic, and sarcomatoid MM. Distinction may be a challenging task for the pathologist, due to the unspecific morphology. Here, we present two cases of diffuse MM subtypes to emphasize the immunohistochemical (IHC) differences, and to facilitate diagnostic difficulties. In our first case of epithelioid mesothelioma, the neoplastic cells showed cytokeratin 5/6 (CK5/6), calretinin, and Wilms-tumor-1 (WT1) expression, while remaining negative with thyroid transcription factor-1 (TTF-1). BRCA1 associated protein-1 (BAP1) negativity was seen in the neoplastic cells' nucleus, reflecting loss of the tumor suppressor gene. In the second case of biphasic mesothelioma, expression of epithelial membrane antigen (EMA), CKAE1/AE3, and mesothelin was observed, while WT1, BerEP4, CD141, TTF1, p63, CD31, calretinin, and BAP1 expressions were not detected. Due to the absence of specific histological features, the differentiation between MM subtypes could be a challenging task. In routine diagnostic work, IHC may be the proper method in distinction. According to our results and literature data, CK5/6, mesothelin, calretinin, and Ki-67 should be applied in subclassification.

ONEST (Observers Needed to Evaluate Subjective Tests) Analysis of Stromal Tumour-Infiltrating Lymphocytes (sTILs) in Breast Cancer and Its Limitations.

Tumour-infiltrating lymphocytes (TILs) reflect antitumour immunity. Their evaluation of histopathology specimens is influenced by several factors and is subject to issues of reproducibility. ONEST (Observers Needed to Evaluate Subjective Tests) helps in determining the number of observers that would be sufficient for the reliable estimation of inter-observer agreement of TIL categorisation. This has not been explored previously in relation to TILs. ONEST analyses, using an open-source software developed by the first author, were performed on TIL quantification in breast cancers taken from two previous studies. These were one reproducibility study involving 49 breast cancers, 23 in the first circulation and 14 pathologists in the second circulation, and one study involving 100 cases and 9 pathologists. In addition to the estimates of the number of observers required, other factors influencing the results of ONEST were examined. The analyses reveal that between six and nine observers (range 2-11) are most commonly needed to give a robust estimate of reproducibility. In addition, the number and experience of observers, the distribution of values around or away from the extremes, and outliers in the classification also influence the results. Due to the simplicity and the potentially relevant information it may give, we propose ONEST to be a part of new reproducibility analyses.

ONEST (Observers Needed to Evaluate Subjective Tests) suggests four or more observers for a reliable assessment of the consistency of histological grading of invasive breast carcinoma: A reproducibility study with a retrospective view on previous studies.

Histological grade is one of the most important prognosticators of breast cancer which is available for nearly all cases. It also makes part of several multivariable analysis derived combined prognostic profiles despite concerns about its reproducibility. The aims included a reproducibility study of grading in the light of a recently described statistical approach, ONEST (Observers Needed to Evaluate Subjective Tests) and review earlier reproducibility studies in the light of the ONEST analysis. Nine pathologists reviewed 50 core needle biopsies and 50 slides from different excision specimens and recorded the scores for gland (tubule) formation, nuclear pleomorphism and mitotic activity as well as histological grade. Overall percent agreement, Fleiss kappa and the intraclass correlation coefficient (ICC) were used for the analysis of reproducibility. ONEST data and curves were generated from 100 random permutations of the participants. ONEST suggested a minimum of 4 observers for the reliable evaluation of reproducibility for both the scored components and grade in either type of specimen. Our results suggested moderate or moderate to good reproducibility of grading (kappa values of 0.51 for excisions, and 0.54 for biopsies and ICCs of 0.70 and 0.69, respectively) with gland formation being the most and nuclear pleomorphism the worst consistently evaluated feature. In studies with sufficient participants (at least 4) and non-pairwise comparisons in the analysis, the reproducibility of histological grading is fair to moderate, whereas studies with fewer participants or pairwise kappa analysis suggest moderate to almost prefect agreement of the results. ONEST is a valuable complementation of reproducibility analyses.

The additional value of ONEST (Observers Needed to Evaluate Subjective Tests) in assessing reproducibility of oestrogen receptor, progesterone receptor, and Ki67 classification in breast cancer.

The reproducibility of assessing potential biomarkers is crucial for their implementation. ONEST (Observers Needed to Evaluate Subjective Tests) has been recently introduced as a new additive evaluation method for the assessment of reliability, by demonstrating how the number of observers impact on interobserver agreement. Oestrogen receptor (ER), progesterone receptor (PR), and Ki67 proliferation marker immunohistochemical stainings were assessed on 50 core needle biopsy and 50 excision samples from breast cancers by 9 pathologists according to daily practice. ER and PR statuses based on the percentages of stained nuclei were the most consistently assessed parameters (intraclass correlation coefficients, ICC 0.918-0.996), whereas Ki67 with 5 different theoretical or St Gallen Consensus Conference-proposed cut-off values demonstrated moderate to good reproducibility (ICC: 0.625-0.760). ONEST highlighted that consistent tests like ER and PR assessment needed only 2 or 3 observers for optimal evaluation of reproducibility, and the width between plots of the best and worst overall percent agreement values for 100 randomly selected permutations of observers was narrow. In contrast, with less consistently evaluated tests of Ki67 categorization, ONEST suggested at least 5 observers required for more trustful assessment of reliability, and the bandwidth of the best and worst plots was wider (up to 34% difference between two observers). ONEST has additional value to traditional calculations of the interobserver agreement by not only highlighting the number of observers needed to trustfully evaluate reproducibility but also by highlighting the rate of agreement with an increasing number of observers and disagreement between the better and worse ratings.

"Dum spiro spero": clinicopathologic characteristics of SARS-CoV-2 infection / "Dum spiro spero": a SARS-CoV-2-fertozés klinikopatológiája 26 eset kapcsán.

Összefoglaló. Bevezetés: A kórboncolás hozzájárul a súlyos akut légzoszervi szindrómát okozó koronavírus-2 (SARS-CoV-2-) fertozés klinikopatológiai vonatkozásainak megismeréséhez. Célkituzés: A SARS-CoV-2-fertozöttek boncolása során gyujtött tapasztalatok bemutatása. Módszer: Egymást követoen boncolt, védooltásban nem részesült, SARS-CoV-2-fertozött elhunytak klinikai adatait, makro- és mikroszkópos észleleteit összegeztük; a tüdokimetszéseket SARS-CoV-2-nukleokapszid-immunfestéssel vizsgáltuk. Eredmények: A boncolást a halálok megállapítására (n = 14), tumorgyanú (n = 9), illetve törvényi kötelezettség (n = 3) miatt végeztük. A fertozést a klinikai észlelés vagy a boncolás során (n = 4) végzett SARS-CoV-2-nukleinsav-teszt igazolta. A tünetes betegség átlagos hossza 12,9 nap volt. 21 betegnél (medián életkor 69 év; 18 férfi) állt fenn COVID-19-pneumonia, mely 16 esetben önmagában, 4 esetben bakteriális pneumoniával vagy álhártyás colitisszel szövodve okozott halált; 1 antikoagulált pneumoniás beteg heveny retroperitonealis vérzésben halt meg. 3 betegnél a halált disszeminálódott malignus tumor, 1 betegnél coronariathrombosis, 1 mentálisan retardált betegnél pedig pulmonalis emboliás szövodmény okozta. A COVID-19-pneumoniás tüdok nehezek, tömöttek és vörösen foltozottak voltak. Szövettanilag a betegség idotartamától függoen diffúz alveolaris károsodás korai exsudativ vagy késobbi proliferativ fázisa látszott atípusos pneumocytákkal; gyakori volt a microthrombosis (n = 7), a macrothrombosis (n = 5), illetve a pulmonalis embolia (n = 4). A SARS-CoV-2-immunfestés pozitívnak bizonyult az esetek 38,5%-ában, dominálóan az exsudativ fázisban. Minden elhunyt társbetegség(ek)ben szenvedett, így magasvérnyomás-betegségben (n = 17), érelmeszesedésben (n = 14), 2-es típusú diabetesben (n = 8), rosszindulatú daganatban (n = 6), krónikus obstruktív tüdobetegségben (n = 4), elhízásban (n = 3), vesetranszplantáció utáni immunszuppresszióban (n = 3). Következtetés: Az irodalmi adatokkal összhangban, halálos COVID-19-pneumonia túlnyomóan idos, társbetegség(ek)tol sújtott férfiakban alakult ki. A boncolási gyakorlatban a SARS-CoV-2-nukleokapszid-immunfestéstol a diffúz alveolaris károsodás korai fázisában várható pozitivitás. Orv Hetil. 2021; 162(45): 1791-1802. INTRODUCTION: Autopsy is an important tool for the evaluation of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Objectice: The aim of this study was to present our experience with autopsies of patients diagnosed with SARS-CoV-2 infection. METHOD: Clinical data, macroscopic and microscopic findings of consecutive postmortems of non-vaccinated SARS-CoV-2 patients are summarized. Lung samples were evaluated with SARS-CoV-2 nucleocapsid immunohistochemistry. RESULTS: Autopsies were performed to determine the cause of death (n = 14), suspected tumours (n = 9) or due to legal obligation (n = 3). SARS-CoV-2 infection was verified by ante mortem (n = 22) and post mortem (n = 4) polymerase chain reaction. The mean duration of symptomatic disease was 12.9 days. Of 21 patients with COVID-19 pneumonia, 16 died of respiratory failure, 4 had additional bacterial pneumonia or Clostridioides difficile infection, and 1 developed hemorrhagic complication (n = 1). Other causes of death included disseminated malignancies (n = 3), coronary thrombosis (n = 1) and pulmonary embolism (n = 1). The affected lungs were heavy and had patchy red appearance. Exudative or proliferative phases of diffuse alveolar damage (DAD) were detected with atypical pneumocytes. Microthrombosis (n = 7), macrothrombosis (n = 5) and pulmonary embolism (n = 4) were frequent. The SARS-CoV-2 immunohistochemical reaction was positive in 38.5% of cases. All patients had co-morbidities, namely, hypertension (n = 17), atherosclerosis (n = 14), diabetes (n = 8), malignancies (n = 6), chronic obstructive pulmonary diseases (n = 4), obesity (n = 3) and immunosuppression after kidney transplantation (n = 3). CONCLUSION: Fatal COVID-19 pneumonia occurred mostly in elderly males with co-morbidities. In the autopsy practice, the SARS-CoV-2 nucleocapsid immunohistochemical reaction may confirm the infectious etiology in the early phase of DAD. Orv Hetil. 2021; 162(45): 1791-1802.