Malignant melanotic Xp11 neoplasms exhibit a clinicopathologic spectrum and gene expression profiling akin to alveolar soft part sarcoma: a proposal for reclassification.

The classification of the distinct group of mesenchymal neoplasms, first described as 'Xp11 translocation perivascular epithelioid cell tumor (PEComa)' and for which the term 'melanotic Xp11 neoplasm' or 'Xp11 neoplasm with melanocytic differentiation' has recently been proposed, remains challenging and controversial. We collected 27 melanotic Xp11 neoplasms, the largest series to date, for a comprehensive evaluation. Fourteen of the cases, together with eight alveolar soft part sarcomas (ASPS), nine conventional PEComas and a control group of seven normal tissues were submitted to RNA sequencing. Follow-up available in 22 patients showed 5-year overall survival and 5-year disease-free survival of 47.6 and 35.7%, respectively, which were similar to ASPS and significantly worse than conventional PEComa. Univariate analysis of location (occurring in the kidney versus not kidney), infiltrative growth pattern, nuclear pleomorphism, mitotic activity ≥2/50 high-power fields (HPF), necrosis and lymphovascular invasion were found to be associated with overall survival and/or disease-free survival. Multivariate analysis identified that location was the only factor found to independently correlate with disease-free survival. More importantly, RNA sequencing-based clustering analysis segregated melanotic Xp11 neoplasm and ASPS from other tumors, including conventional PEComa and Xp11 translocation renal cell carcinoma, and formed a compact cluster representative of the largely similar expression signature. Here we clearly define the true biologic nature of melanotic Xp11 neoplasms which are distinctive malignant mesenchymal tumors, rather than simply PEComa variants with occasionally unpredictable behavior. Meanwhile, melanotic Xp11 neoplasm and ASPS more likely represent phenotypic variants of the same entity, which is distinct from conventional PEComa and Xp11 translocation renal cell carcinoma. Based on these important findings, melanotic Xp11 neoplasm might be reclassified into a distinctive entity together with ASPS, independent from PEComa, in future revisions of the current WHO categories of tumors of soft tissue and bone for the improved reclassification. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

RNA sequencing of Xp11 translocation-associated cancers reveals novel gene fusions and distinctive clinicopathologic correlations.

Both Xp11 translocation renal cell carcinomas and the corresponding mesenchymal neoplasms are characterized by a variety of gene fusions involving TFE3. It has been known that tumors with different gene fusions may have different clinicopathologic features; however, further in-depth investigations of subtyping Xp11 translocation-associated cancers are needed in order to explore more meaningful clinicopathologic correlations. A total of 22 unusual cases of Xp11 translocation-associated cancers were selected for the current study; 20 cases were further analyzed by RNA sequencing to explore their TFE3 gene fusion partners. RNA sequencing identified 17 of 20 cases (85%) with TFE3-associated gene fusions, including 4 ASPSCR1/ASPL-TFE3, 3 PRCC-TFE3, 3 SFPQ/PSF-TFE3, 1 NONO-TFE3, 4 MED15-TFE3, 1 MATR3-TFE3, and 1 FUBP1-TFE3. The results have been verified by fusion fluorescence in situ hybridization (FISH) assays or reverse transcriptase polymerase chain reaction (RT-PCR). The remaining 2 cases with specific pathologic features highly suggestive of MED15-TFE3 renal cell carcinoma were identified by fusion FISH assay. We provide the detailed morphologic and immunophenotypic description of the MED15-TFE3 renal cell carcinomas, which frequently demonstrate extensively cystic architecture, similar to multilocular cystic renal neoplasm of low malignant potential, and expressed cathepsin K and melanotic biomarker Melan A. This is the first time to correlate the MED15-TFE3 renal cell carcinoma with specific clinicopathologic features. We also report the first case of the corresponding mesenchymal neoplasm with MED15-TFE3 gene fusion. Additional novel TFE3 gene fusion partners, MATR3 and FUBP1, were identified. Cases with ASPSCR1-TFE3, SFPQ-TFE3, PRCC-TFE3, and NONO-TFE3 gene fusion showed a wide variability in morphologic features, including invasive tubulopapillary pattern simulating collecting duct carcinoma, extensive calcification and ossification, and overlapping and high columnar cells with nuclear grooves mimicking tall cell variant of papillary thyroid carcinoma. Furthermore, we respectively evaluated the ability of TFE3 immunohistochemistry, TFE3 FISH, RT-PCR, and RNA sequencing to subclassify Xp11 translocation-associated cancers. In summary, our study expands the list of TFE3 gene fusion partners and the clinicopathologic features of Xp11 translocation-associated cancers, and highlights the importance of subtyping Xp11 translocation-associated cancers combining morphology, immunohistochemistry, and multiple molecular techniques.

Novel gene fusion of PRCC-MITF defines a new member of MiT family translocation renal cell carcinoma: clinicopathological analysis and detection of the gene fusion by RNA sequencing and FISH.

AIMS: MITF, TFE3, TFEB and TFEC belong to the same microphthalmia-associated transcription factor family (MiT). Two transcription factors in this family have been identified in two unusual types of renal cell carcinoma (RCC): Xp11 translocation RCC harbouring TFE3 gene fusions and t(6;11) RCC harbouring a MALAT1-TFEB gene fusion. The 2016 World Health Organisation classification of renal neoplasia grouped these two neoplasms together under the category of MiT family translocation RCC. RCCs associated with the other two MiT family members, MITF and TFEC, have rarely been reported. Herein, we identify a case of MITF translocation RCC with the novel PRCC-MITF gene fusion by RNA sequencing. METHODS AND RESULTS: Histological examination of the present tumour showed typical features of MiT family translocation RCCs, overlapping with Xp11 translocation RCC and t(6;11) RCC. However, this tumour showed negative results in TFE3 and TFEB immunochemistry and split fluorescence in-situ hybridisation (FISH) assays. The other MiT family members, MITF and TFEC, were tested further immunochemically and also showed negative results. RNA sequencing and reverse transcription-polymerase chain reaction confirmed the presence of a PRCC-MITF gene fusion: a fusion of PRCC exon 5 to MITF exon 4. We then developed FISH assays covering MITF break-apart probes and PRCC-MITF fusion probes to detect the MITF gene rearrangement. CONCLUSIONS: This study both proves the recurring existence of MITF translocation RCC and expands the genotype spectrum of MiT family translocation RCCs.

Xp11.2 translocation renal cell carcinoma with NONO-TFE3 gene fusion: morphology, prognosis, and potential pitfall in detecting TFE3 gene rearrangement.

Xp11 translocation renal cell carcinomas are characterized by several different translocations involving the TFE3 gene. Tumors with different specific gene fusions may have different clinicopathological manifestations. Fewer than 10 renal cell carcinoma cases with NONO-TFE3 have been described. Here we examined eight additional cases of this rare tumor using clinicopathological, immunohistochemical, and molecular analyses. The male-to-female ratio of our study cohort was 1:1, and the median age was 30 years. The most distinctive feature of the tumors was that they exhibited glandular/tubular or papillary architecture that was lined with small-to-medium cuboidal to high columnar cells with indistinct cell borders and an abundantly clear or flocculent eosinophilic cytoplasm. The nuclei were oriented toward the luminal surface and were round and uniform in shape, which resulted in the appearance of secretory endometrioid subnuclear vacuolization. The distinct glandular/tubular or papillary architecture was often accompanied by sheets of epithelial cells that presented a biphasic pattern. Immunohistochemically, all eight cases demonstrated moderate (2+) or strong (3+) positive staining for TFE3, CD10, RCC marker, and PAX-8. None of the tumors were immunoreactive for CK7, Cathepsin K, Melan-A, HMB45, Ksp-cadherin, Vimentin, CA9, 34ßE12 or CD117. NONO-TFE3 fusion transcripts were identified in six cases by RT-PCR. All eight cases showed equivocal split signals with a distance of nearly 2 signal diameters and sometimes had false-negative results. Furthermore, we developed a fluorescence in situ hybridization (FISH) assay to serve as an adjunct diagnostic tool for the detection of the NONO-TFE3 fusion gene and used this method to detect the fusion gene in all eight cases. Long-term follow-up (range, 10-102 months) was available for 7 patients. All 7 patients were alive with no evidence of recurrent disease or disease progression after their initial resection. This report adds to the known data regarding NONO-TFE3 renal cell carcinoma.

BRM/SMARCA2-negative clear cell renal cell carcinoma is associated with a high percentage of BRM somatic mutations, deletions and promoter methylation.

AIMS: The aim of this study was to investigate potential molecular mechanisms associated with loss of BRM expression in poorly differentiated clear cell renal cell carcinoma (ccRCC). METHODS AND RESULTS: Nineteen previously selected BRM-negative RCC tissues were examined by DNA sequencing, fluorescence in-situ hybridization (FISH) and methylation-specific polymerase chain reaction (PCR) of the BRM gene. BRM mutation was identified in 78.9% (15 of 19) cases, chromosome 9 monosomy or BRM deletion in 43.8% (seven of 16) and BRM promoter region cytosine-phosphate-guanine (CpG) methylation in 42.8% (six of 14). These results indicated that 89.5% (17 of 19) of the cases harboured at least one type of BRM genetic alteration, with two or more types of alteration in 47.4% (nine of 19). Such alterations were found rarely in adjacent non-neoplastic tissues and low-grade areas of composite tumours. CONCLUSIONS: BRM gene mutation, chromosome 9 monosomy or BRM deletion and CpG methylation contribute collectively to the loss of BRM expression in ccRCC. This work focusing on composite tumours indicated that BRM abnormality occurred during tumour progression.

EWSR1 rearrangement is present in a subset of myoepithelial tumors of salivary glands with variable morphology and does not correlate with clinical behavior.

To investigate that whether myoepithelial tumors of salivary glands (MTs) with EWSR1 rearrangement display distinctive morphological characteristics and whether EWSR1 detection aids to distinguish malignant myoepithelial tumors (MMTs) from benign myoepithelial tumors (BMTs) of salivary glands. We examined 37 cases of MTs, including 24 BMTs, 13 MMTs, by histological, immunohistochemical, and molecular analysis. All of 37 cases were immunoreactive for CKpan, and at least one myoepithelial marker. 26 of 37 cases of MTs were available to be analyzed for EWSR1 rearrangement, with the result that EWSR1 gene break was detected in 4 cases of 15 BMTs, and 4 cases of 11 MMTs. In addition, the 8 EWSR1-rearranged cases displayed not exactly similar morphological features, covering 4 clear-cell cases, 1 plasmacytoid-cell case, 1 spindle-cell case, 1 epithelioid-cell case, and 1 chordoid-cell case. Our study proposed that EWSR1 rearrangement was present in a subset of MTs, with variable morphological features. Moreover, the presence of EWSR1 rearrangement could not be a forceful evidence to distinguish MMTs from BBTs.

Xp11 neoplasm with melanocytic differentiation of the prostate harbouring the novel NONO-TFE3 gene fusion: report of a unique case expanding the gene fusion spectrum.

Recently, an increasing number of TFE3 rearrangement-associated tumours have been reported, such as TFE3 rearrangement-associated perivascular epithelioid cell tumours (PEComas), melanotic Xp11 translocation renal cancers and melanotic Xp11 neoplasms. We have suggested that these tumours belong to a single clinicopathological spectrum. 'Xp11 neoplasm with melanocytic differentiation' or 'melanotic Xp11 neoplasm' have been proposed to designate this unique neoplasm. Herein, we describe the first case of an Xp11 neoplasm with melanocytic differentiation to be described in the prostate, bearing the novel NONO-TFE3 gene fusion. This study both adds to the spectrum regarding melanotic Xp11 neoplasms and expands its gene fusion spectrum. Moreover, we discuss the relationship of these rare tumours to neoplasms such as conventional PEComas, alveolar soft part sarcomas, malignant melanomas, clear cell sarcomas and Xp11 translocation renal cancers.

Frequent co-inactivation of the SWI/SNF subunits SMARCB1, SMARCA2 and PBRM1 in malignant rhabdoid tumours.

AIMS: Malignant rhabdoid tumours (MRTs) are highly aggressive malignancies of early infancy characterized by inactivation of SMARCB1, a core member of the SWI/SNF chromatin-remodelling complex. The aim of this study was to explore the status of multiple key subunits of the SWI/SNF complex in MRTs. METHODS AND RESULTS: We screened the key subunits of the SWI/SNF complex, including SMARCB1, SMARCA2, PBRM1, SMARCA4, and ARID1A, in four MRTs by immunohistochemistry, sequencing, and fluorescence in-situ hybridization (FISH). Complete loss of SMARCB1, SMARCA2 and PBRM1 expression and corresponding mutations in the same genes were observed in all cases. The mutations included seven missense, three same-sense, four frameshift and two truncating mutations. FISH revealed heterozygous deletion of SMARCB1 in one case, and monoploidy of chromosome 22, which harbours SMARCB1, in another case. Furthermore, trisomy of chromosome 9, which harbours SMARCA2, was observed in two cases. Abnormality of PBRM1 was not found in any case. CONCLUSIONS: We report, for the first time, co-inactivation and frequent mutations of SMARCB1, SMARCA2 and PBRM1 in MRTs. Multiple subunit abnormalities of the SWI/SNF complex potentially act together to contribute to the tumorigenesis of MRTs, which provides unique insights into this disease.

Loss of BRM expression is a frequently observed event in poorly differentiated clear cell renal cell carcinoma.

AIMS: The aim of this study was to examine the status of Brahma (BRM), a key SWI/SNF complex subunit, in clear cell renal cell carcinomas (RCCs), and to analyse the histopathology, immunophenotype, molecular features and prognosis of the BRM-negative cases. METHODS AND RESULTS: We identified 19 cases of grade 4 tumours lacking BRM expression among 625 clear cell RCCs. All 19 cases exhibited features of poor differentiation: 13 showed pure poorly differentiated morphology, while six were composite tumours with an admixed typical low-grade component. Besides negative BRM expression, the immunophenotype of these cases was similar to clear cell RCC. VHL gene mutations were identified in nine of the 19 patients (47%). Chromosome 3p deletion was detected in 11 of 13 poorly differentiated RCCs and both areas of five of five composite tumours. All poorly differentiated tumour areas showed polysomy of chromosome 3. No losses or gains of chromosome 3 were observed in low-grade tumour areas of five of five composite RCCs. CONCLUSIONS: We have shown that loss of BRM expression is a common feature among poorly differentiated tumours in clear cell RCCs. We hypothesize that loss of BRM expression is involved in tumor de-differentiation in clear cell RCCs and may play an important role during tumour progression.

[Primary testicular yolk sac tumor: clinicopathological study of 8 cases].

OBJECTIVE: To investigate the clinicopathological characteristics, diagnosis and treatment of primary testicular yolk sac tumor (YST). METHODS: We studied 8 cases of primary testicular YST by microscopy and immunohistochemistry. RESULTS: The 8 cases of primary testicular YST, including 2 consultation cases, were confirmed from 1998 to 2013, accounting for 10.7% (8/75) of all the testicular germ cell tumors diagnosed in our hospital. The patients ranged in age from 7 to 43 years, 23.9 years on average. The main clinical manifestation of the patients was painless unilateral testis swelling. Microscopically, reticular tissues, schiller-duvaI (S-D) bodies, and eosin-stain transparent bodies were seen in the tumors. One of the cases was confirmed to be simple YST, while the other 7 mixed YST. AFP was a characteristic immunophenotype marker of the tumors. CONCLUSION: Primary testicular YST is a rare malignancyr with poor prognosis. Its diagnosis depends on preoperative AFP test and postoperative pathology. Comprehensive treatment, including orchiectomy, chemotherapy, and radiotherapy, can prolong the survival of the patients.

[Primary neuroendocrine tumor of the testis: clinicopathological study of 7 cases].

OBJECTIVE: To investigate the clinicopathologic characteristics, diagnosis, differential diagnosis and treatment of primary neuroendocrine tumor (NET) of the testis. METHODS: Using light microscopy and immunohistochemistry, we studied 7 cases of primary NET of the testis, reviewed relevant literature, and analyzed the clinical manifestations, histomorphologic and immunohistochemical characteristics, treatment and prognosis of the tumor. RESULTS: The 7 male patients, at the mean age of 40.6 years, all presented with testicular painless masses, none accompanied with carcinoid syndrome. Histologically, the uniform tumor cells were arranged in trabecular, island, solid and/or flake structures and locally in a tubulo glandular pattern, round and polygonal in shape, with a small amount of lipid vacuoles in the eosinophilic cytoplasm. The cells had round nuclei with fine chromatin and rarely identified mitosis. Immunohistochemical staining showed that the tumor cells were positive for Syn, CgA, NSE and CK, with a Ki-67 positive rate of < 2%. CONCLUSION: Primary NET of the testis is a rare and low-grade malignancy. Early diagnosis and surgical resection are essential for good prognosis. Immunohistochemistry helps its diagnosis and differential diagnosis from other metastatic neuroendocrine carcinoma, teratomas with carcinoid, seminoma, and Sertoli cell tumor.

Cathepsin K expression in a wide spectrum of perivascular epithelioid cell neoplasms (PEComas): a clinicopathological study emphasizing extrarenal PEComas.

AIMS: Recent studies have demonstrated that cathepsin K seems to be a powerful marker in identifying renal perivascular epithelioid cell neoplasms (PEComas). However, the expression in extrarenal PEComas has not been well characterized due to their rare incidence. Our aim was to investigate the expression of cathepsin K in a wide spectrum of extrarenal PEComas and evaluate its potential diagnostic usefulness in comparison with other commonly used markers. METHODS AND RESULTS: Twenty-three cases of PEComa (liver, n = 9; lung, n = 1; broad ligament of uterus, n = 1; vertex subcutaneous soft tissue, n = 1; abdominal wall, n = 1; and kidney, n = 10) were selected for study. All displayed a high percentage of cells with moderately to strongly positive reactions for cathepsin K (mean 91%; range 80-100%). HMB45, Melan-A and smooth muscle actin (SMA) were expressed in 78, 87 and 87% of cases, respectively, with various percentages of positive cells (mean, 34, 40 and 38%; range 0-80, 0-90 and 0-90%). Transcription factor E3 (TFE3) was expressed strongly in only three cases; none exhibited evidence of TFE3 gene fusion or amplification. CONCLUSIONS: Cathepsin K appears to be more powerful than other commonly used markers in diagnosing a wide spectrum of PEComas and distinguishing them from the majority of human cancers.

[Immunohistochemistry using epidermal growth factor receptor mutation-specific antibodies of delE746-A750 and L858R in lung adenocarcinomas].

OBJECTIVE: To evaluate the immunohistochemical detection of epidermal growth factor receptor(EGFR) mutations using two EGFR mutation-specific monoclonal antibodies: delE746-A750 and L858R. METHODS: A total of 175 paraffin-embedded lung adenocarcinoma tissue samples previously genotyped by directive DNA sequencing were subject to immunostaining using delE746-A750 and L858R antibodies. RESULTS: There was no significant difference of mutation detection between DNA sequence analysis and delE746-A750 and/or L858R immunostaining (33.7% vs 30.9%, P > 0.05). The overall sensitivity, specificity, positive predictive value and negative predictive value of immunostaining using these two EGFR mutation-specific antibodies were 83.1%, 95.7%, 90.7% and 90.9%, respectively. CONCLUSION: With high sensitivity and good specificity, immunohistochemistry using EGFR mutation-specific monoclonal antibodies is an adequate, easy and cost-effective prescreening method to detect EGFR mutations using paraffin-embedded tissue specimens of lung adenocarcinomas.

[Immunohistochemical study of perivascular epithelioid cell neoplasms].

OBJECTIVE: To study the clinicopathologic features, immunophenotype and genetic changes of perivascular epithelioid cell neoplasms (PEComa). METHODS: A total of 25 cases of PEComa located in various anatomic sites were selected for immunohistochemical staining (SP or EnVision method). TFE3 fluorescence in-situ hybridization was also performed to determine the TFE3 gene status. RESULTS: The age of patient ranged from 21 to 61 years (mean = 43 years). The male-to-female ratio was 1: 1.3. Histologically, 22 cases represented conventional angiomyolipomas, composed of a mixture of adipose tissue, spindle element, epithelioid smooth muscle cells and abnormal thick-walled blood vessels in various proportions. Three cases involving lung, soft tissue and broad ligament had subtle but distinctive morphologic features. Nested or sheet-like architecture with epithelioid or spindle cells was observed. Immunohistochemical study showed that HMB 45, melan A, smooth muscle actin and cathepsin K were expressed in 80% (20/25), 88% (22/25), 88% (22/25) and 100% (25/25) of PEComa, respectively. Within positive cases, the average proportion of positive tumor cells was 36%, 41%, 35% and 90% respectively for HMB 45, melan A, smooth muscle actin and cathepsin K. TFE3 was negative in all of the 22 renal and hepatic PEComa studied, while it was positive in the 3 cases of extra-hepatorenal PEComa. None of the 25 cases exhibited evidence of TFE3 gene fusion or amplification. CONCLUSIONS: Extra-hepatorenal PEComa have distinctive morphologic features and are associated with TFE3 overexpression. Cathepsin K immunostaining demonstrates high sensitivity and specificity in PEComa, better than other commonly employed immunomarkers. This marker is thus useful in diagnosis of PEComa and distinction with other neoplasms.

[Prognostic significance of a newly proposed grading and scoring system in stage I pulmonary adenocarcinoma].

OBJECTIVE: To evaluate the prognostic significance of a new grading and scoring system (based on the new IASLC/ATS/ERS classification) in stage I pulmonary adenocarcinoma, as compared with the WHO grading system. METHODS: The clinicopathologic characteristics of 125 patients with stage I pulmonary adenocarcinoma primarily treated by surgical resection were reviewed retrospectively. All cases were classified according to the new IASLC/ATS/ERS classification and graded into three prognostic groups based on the new classification, the Sica scoring system and the WHO grading system, respectively. The differences in prognosis of the three groups were analyzed. RESULTS: There was a statistically significant correlation between the new grading system and the WHO grading system (P = 0.000). Both of them showed negative correlation with overall survival. The new scoring system however better correlated with disease recurrence and/or metastasis (P = 0.855, P = 0.073 versus P = 0.011). According to univariate Log-rank test, the prognosis correlated with tumor size (P = 0.004), clinical stage (P = 0.000), the WHO grading (P = 0.020), the new grading system (P = 0.000), the new scoring system (P = 0.000), vascular invasion (P = 0.021), and recurrence and/or metastasis (P = 0.000). The Cox regression analysis demonstrated that clinical stage (P = 0.014), the new grading system (P = 0.047), the new scoring system (P = 0.043), and recurrence and/or metastasis (P = 0.018) were significantly independent poor prognostic factors. CONCLUSIONS: The new grading and scoring system shows good correlation with the WHO grading system. Compared with the WHO grading system, the new scoring system based on the new IASLC/ATS/ERS classification provides valuable information in categorizing stage I pulmonary adenocarcinoma cases with different risks of disease recurrence, tumor metastasis and prognosis.

[Male genitourinary system lymphoma: a clinicopathological analysis].

OBJECTIVE: To investigate the clinicopathological features and immunophenotypes of male genitourinary system lymphoma. METHODS: We retrospectively studied the histopathological characteristics and immunohistochemical markers of 35 cases of male genitourinary system lymphoma, and reviewed the relevant literature. RESULTS: The 35 patients of male genitourinary system lymphoma were aged from 4 to 83 (mean 56.5) years, 28 (80%) of them > or = 50 years. Twenty-eight cases (80%) involved the testis, 3 (8.6%) the prostate, 1 (2.9%) the spermatic cord, 1 the seminal vesicles, 1 the penis and 1 the epididymis. Histologically, 22 cases (62.9%) were diffused large B cell lymphoma (DLBCL), 6 (17.1%) mucosa associated lymphoid tissue (MALT) lymphoma, 4 (11.4%) Burkitt lymphoma, 2 (5.7%) peripheral T cell lymphoma, and 1 (2.9%) plasmacytoma. CONCLUSION: Male genitourinary system lymphomas are rare tumors clinically, which occur more often in the elderly. The majority of them are B cell lymphomas, of which the most common is DLBCL, followed by MALT lymphoma and Burkitt lymphoma. T cell lymphoma and plasmacytoma are rare. The diagnosis of male genitourinary system lymphoma relies on the histopathology, and immunohistochemical markers are of high value for its definite diagnosis, classification and differential diagnosis.

TSC/MTOR -associated Eosinophilic Renal Tumors Exhibit a Heterogeneous Clinicopathologic Spectrum : A Targeted Next-generation Sequencing and Gene Expression Profiling Study.

BACKGROUND: Several TSC1/2- or MTOR -mutated eosinophilic renal tumor subsets are emerging, including eosinophilic solid and cystic renal cell carcinoma (ESC RCC), eosinophilic vacuolated tumors (EVTs) and low-grade oncocytic tumors (LOTs). "Unclassified renal tumors with TSC/MTOR mutations" ( TSC -mt RCC-NOS) do not meet the criteria for other histomolecular subtypes. Whether these tumors represent a continuum of 1 TS C/ MTOR -mutation-associated disease is unknown. DESIGN: We evaluated the clinicopathologic and IHC profiles of 39 eosinophilic renal tumors with targeted DNA sequencing-confirmed TSC/MTOR mutations. Twenty-eight of these, plus 6 ChRCC, 5 RO, 5 ccRCC, 7 MiT RCC and 6 normal renal tissues, were profiled transcriptionally by RNA-seq. RESULTS: The 39 cases were reclassified based on morphological and IHC features as ESC RCC (12), EVT (9), LOT, (8) and TSC -mt RCC-NOS (10). The mutation profiles demonstrated consistency; ESC RCCs (12/12) had TSC mutations, and most LOTs (7/8) had MTOR mutations. Ten TSC -mt RCC-NOSs exhibited heterogeneous morphology, arising a differential diagnosis with other renal tumors, including MiT RCC, PRCC and epithelioid PEComa. RNA sequencing-based clustering segregated ESC RCC, EVT and LOT from each other and other renal tumors, indicating expression profile-level differences. Most TSC- mt RCC-NOSs (6/7) formed a mixed cluster with ESC RCC, indicating similar expression signatures; one TSC- mt RCC-NOS with unusual biphasic morphology clustered with EVT. CONCLUSIONS: We expanded the TSC/MTOR -associated eosinophilic renal tumor morphologic spectrum, identified gene mutation characteristics, and highlighted differential diagnosis challenges, especially with MiT RCC. ESC RCC, EVT, and LOT having distinct expression profiles. TSC -mt RCC-NOS may cluster with recognized TSC/MTOR -associated entities.

Clinicopathological and molecular characterization of biphasic hyalinizing psammomatous renal cell carcinoma: further support for the newly proposed entity.

The classification of renal neoplasms continues to evolve with novel, emerging, and provisional entities being described constantly. Biphasic hyalinizing psammomatous renal cell carcinoma (BHP RCC) associated with somatic NF2 mutations is one such new renal entity and is considered as a provisional category of RCC due to its very limited data. To provide further support for the newly proposed entity, we identified three additional cases of BHP RCC, with clinicopathological, immunohistochemical, and various molecular analyses. There were 2 males and 1 female, aged 65, 56, and 69 years, respectively. The neoplasms were unencapsulated, and all had a characteristic biphasic appearance of smaller cells clustering around basement membrane material within larger acini, forming pseudorosettes or a glomeruloid pattern. Hyalinized sclerotic stroma and psammoma bodies were abundant in two cases and focally present in one case. Focal areas of a less distinctive appearance were also noted; one additionally had an elongated tubular pattern in the myxoid stroma that is reminiscent of mucinous tubular and spindle cell carcinoma; one consisted solid alveolar architectures of epithelioid clear cells, bearing some resemblance to clear cell RCC. The neoplasms did not have a distinctive immunohistochemistry (IHC) profile, though all labeled for vimentin and CK7. Targeted DNA sequencing revealed that one case harbored a pathogenic somatic frameshift mutation in the NF2 gene, which was further confirmed by Sanger sequencing. The other two cases lacked NF2 mutations and instead demonstrated NF2 promoter methylation by methylation-specific polymerase chain reaction. Subsequent IHC assessment showed loss of expression of NF2 in all 3 cases, which evaluated NF2 status at the protein level. According to RNA sequencing-based clustering analysis, the 3 cases formed a distinct group with a shared specific transcriptional profile different from that of other established renal tumor types. In addition, phosphate inositide 3-kinase (PI3K)/AKT pathway was enriched significantly and on the top of all enriched pathways. Clinically, one patient developed bone metastases and died of disease two years after diagnosis. The other two patients had no evidence of recurrence or metastases, at 4- and 5-year follow-up. These findings not only validate previously described clinicopathological features but also expand the potentially genetic alterations and available clinical outcome data.

[Mucinous tubular and spindle cell carcinoma of kidney: a clinicopathological study].

OBJECTIVE: To investigate the clinicopathological features, histogenesis and prognosis of mucinous tubular and spindle cell carcinoma (MTSCC). METHODS: Five MTSCCs were studied with histochemical, immunohistochemical staining, electron microscopy, and review of the related literatures. RESULTS: Four cases of MTSCC were females and one was male. Three patients presented with flank discomfort and two were incidentally found with health examination. In gross examination, the tumors were circumscribed. The cut surface was solid, gray-white, yellow or red. Necrosis was present in one case of high-grade MTSCC. Microscopically, low-grade MTSCC was mainly consisted of tubular, spindle cell and mucinous stroma with relatively bland morphology, and mitoses were rare. While in the high-grade area of one case, the cells were spindle or polymorphic with severe atypia and high mitotic activity, without mucinous stroma and tubular structure. Mucin was positive for Alcian blue. The neoplastic cells were positive for vimentin (5/5), CKpan (5/5), CK7 (5/5), CK19 (5/5), 34betaE12 (1/5), EMA (5/5), E-cadherin (3/5), CD10 (1/5), P504S (5/5), and CAM5.2 (5/5). The Ki-67 index was low (< or = 5%) in the low-grade component, while it was high (15%) in the high-grade component. Ultrastructural study showed short microvilli along glandular lumens. The nuclear membrane was focally invaginated. Four cases were followed up for 3 to 52 months, and recurrence and metastasis were not found. CONCLUSIONS: MTSCC occurs predominantly in females and it is a rare kidney neoplasm. Most of MTSCCs are low-grade and the prognosis is relatively good. However, the patients of high-grade MTSCC should be closely followed up.

[Clinicopathological analysis of testicular mixed germ cell tumor].

OBJECTIVE: To investigate the clinicopathological characteristics of primary testicular mixed germ cell tumor (MGCT). METHODS: We retrospectively analyzed the clinicopathological data of 13 cases of primary testicular MGCT and reviewed other relevant literature. RESULTS: MGCT accounted for 24.1% (13/54) of all the testicular germ cell tumors diagnosed in our hospital. The patients ranged in age from 2 to 53 years, averaging at 28.3 years. All were unilateral cases, 6 in the left and 7 in the right testis, with a left/right ratio of 0.86:1. Morphologically, testicular MGCT displayed a variety of subtypes, embryonal carcinoma in 11 cases (84.6%), seminoma in 8 (61.5%), teratoma in 6 (46.2%), choriocarcinoma in 4 (30.8%) and yolk sac tumor in 4 (30.8%). Nine of the cases (69.2%) were composed of two different germ cell histological elements, 3 (23.1%) composed of three, and 1 (7.7%) composed of five. CONCLUSION: Testicular MGCT is rather rare and most commonly occurs in young men. Its biological behavior, clinical management and prognosis vary with its different histological elements. Therefore accurate pathological diagnosis is essential and immunohistochemistry plays an important role in the diagnosis and differential diagnosis of testicular MGCT.