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.

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.

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.

[Myxoinflammatory fibroblastic sarcoma of the lower limb]

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.

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.

“Dum spiro spero”: clinicopathologic characteristics of SARS-CoV-2 infection

Összefoglaló. Bevezetés: A kórboncolás hozzájárul a súlyos akut légzőszervi szindrómát okozó koronavírus-2 (SARS-CoV-2-) fertőzés klinikopatológiai vonatkozásainak megismeréséhez. Célkitűzés: A SARS-CoV-2-fertőzöttek boncolása során gyűjtött tapasztalatok bemutatása. Módszer: Egymást követően boncolt, védőoltásban nem részesült, SARS-CoV-2-fertőzött elhunytak klinikai adatait, makro- és mikroszkópos észleleteit összegeztük; a tüdőkimetszéseket 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 fertőzést 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 szövődve 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 szövődmény okozta. A COVID-19-pneumoniás tüdők nehezek, tömöttek és vörösen foltozottak voltak. Szövettanilag a betegség időtartamától függően diffúz alveolaris károsodás korai exsudativ vagy későbbi 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 tüdőbetegségben (n = 4), elhízásban (n = 3), vesetranszplantáció utáni immunszuppresszióban (n = 3). Következtetés: Az irodalmi adatokkal összhangban, halálos COVID-19-pneumonia túlnyomóan idős, társbetegség(ek)től sújtott férfiakban alakult ki. A boncolási gyakorlatban a SARS-CoV-2-nukleokapszid-immunfestéstől a diffúz alveolaris károsodás korai fázisában várható pozitivitás. Orv Hetil. 2021; 162(45): 1791-1802.

SUMMARY

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.

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.