Mathieu Latour

Grading of invasive cribriform carcinoma on prostate needle biopsy: an interobserver study among experts in genitourinary pathology

The distinction between cribriform Gleason pattern 3 and 4 prostate cancer is controversial. Out of 3590 prostate cancers sent to one of the authors over 7 months, 30 needle biopsy cases were selected that possibly represented cribriform Gleason pattern 3 cancer. Thirty-six digital images were taken and sent to 10 experts in prostate pathology. Consensus was defined when at least 7/10 experts agreed on the grade. Sixty-seven percent (n=24) of images reached consensus (23 pattern 4; 1 pattern 3). Of the 12 nonconsensus images, 7 were favor pattern 4 (6/10 experts agreed), 1 was favor pattern 3 (6/10 experts agreed), and 4 were equivocal (<6 experts agreed). The most common criteria used to call pattern 4 in the 23 consensus pattern 4 images were in frequency: irregular contour, irregular distribution of lumens, slit-like lumens, large glands, number of glands, and small lumens. In the only consensus pattern 3 image, criteria used were regular contour, small glands, regular distribution of lumens, and uniform round lumens. Discrepancy between experts was qualified as primarily objective (different criteria present) in 38%, subjective (different interpretation of the same criteria) in 12%, and mixed (both objective and subjective) in 50%. The most frequent situation with different interpretations of the same criteria were regular versus irregular contour and small versus large glands, with the former more common. Even in this highly selected set of images thought to be the best candidates for cribriform pattern 3 from a busy consult service, most experts interpreted the cribriform patterns as pattern 4. Moreover, most of the cribriform foci investigated (73%) were associated with more definitive pattern 4 elsewhere on the needle biopsy specimen. In conclusion, most of the small cribriform cancer foci seen on needle biopsy should be interpreted as Gleason pattern 4 and not pattern 3.

TMPRSS2–ERG gene fusion status in minute (minimal) prostatic adenocarcinoma

Minute prostatic adenocarcinomas are considered to be of insufficient virulence. Given recent suggestions of TMPRSS2–ERG gene fusion association with aggressive prostatic adenocarcinoma, we evaluated the incidence of TMPRSS2–ERG fusion in minute prostatic adenocarcinomas. A total of 45 consecutive prostatectomies with minute adenocarcinoma were used for tissue microarray construction. A total of 63 consecutive non-minimal, Gleason Score 6 tumors, from a separate PSA Era prostatectomy tissue microarray, were used for comparison. FISH was carried out using ERG break-apart probes. Tumors were assessed for fusion by deletion (Edel) or split (Esplit), duplicated fusions and low-level copy number gain in normal ERG gene locus. Minute adenocarcinomas: Fusion was evaluable in 32/45 tumors (71%). Fifteen out of 32 (47%) tumors were positive for fusion. Six (19%) were of the Edel class and 7 (22%) were classified as combined Edel+Esplit. Non-minute adenocarcinomas (pT2): Fusion was identified in 20/30 tumors (67%). Four (13%) were of Edel class and 5 (17%) were combined Edel+Esplit. Duplicated fusions were encountered in 5 (16%) tumors. Non-minute adenocarcinomas (pT3): Fusion was identified in 19/33 (58%). Fusion was due to a deletion in 6 (18%) tumors. Seven tumors (21%) were classified as combined Edel+Esplit. One tumor showed Esplit alone. Duplicated fusions were encountered in 3 (9%) cases. The incidence of duplicated fusions was higher in non-minute adenocarcinomas (13 vs 0%; P=0.03). A trend for higher incidence of low-level copy number gain in normal ERG gene locus without fusion was noted in non-minute adenocarcinomas (10 vs 0%; P=0.07). We found a TMPRSS2–ERG fusion rate of 47% in minute adenocarcinomas. The latter is not significantly different from that of grade matched non-minute adenocarcinomas. The incidence of duplicated fusion was higher in non-minute adenocarcinomas. Our finding of comparable rate of TMPRSS2–ERG fusion in minute adenocarcinomas may argue against its value as a marker of aggressive prostate carcinoma phenotype.

TMPRSS2-ERG gene fusions are infrequent in prostatic ductal adenocarcinomas

Ductal adenocarcinoma of the prostate is an unusual subtype that may be associated with a more aggressive clinical course, and is less responsive to conventional therapies than the more common prostatic acinar adenocarcinoma. However, given its frequent association with an acinar component at prostatectomy, some have challenged the concept of prostatic ductal adenocarcinoma as a distinct clinicopathologic entity. We studied the occurrence of the TMPRSS2-ERG gene fusion, in 40 surgically resected ductal adenocarcinoma cases, and in their associated acinar component using fluorescence in situ hybridization. A group of 38 ‘pure’ acinar adenocarcinoma cases matched with the ductal adenocarcinoma group for pathological grade and stage was studied as a control. Compared with the matched acinar adenocarcinoma cases, the TMPRSS2-ERG gene fusion was significantly less frequently observed in ductal adenocarcinoma (45 vs 11% of cases, P=0.002, Fishers exact test). Here, of the ductal adenocarcinoma cases with the gene fusion, 75% were fused through deletion, and the remaining case was fused through translocation. The TMPRSS2-ERG gene fusion was also rare in the acinar component of mixed ductal–acinar tumors when compared with the pure acinar adenocarcinoma controls (5 vs 45%, P=0.001, Fishers exact test). In 95% of the ductal adenocarcinoma cases in which a concurrent acinar component was analyzed, there was concordance for presence/absence of the TMPRSS2-ERG gene fusion between the different histologic subtypes. In the control group of pure acinar adenocarcinoma cases, 59% were fused through deletion and 41% were fused through translocation. The presence of the TMPRSS2-ERG gene fusion in some cases of prostatic ductal adenocarcinoma supports the concept that ductal adenocarcinoma and acinar adenocarcinoma may be related genetically. However, the significantly lower rate of the gene fusion in pure ductal adenocarcinoma cases underscores the fact that genetic and biologic differences exist between these two tumors that may be important for future therapeutic strategies.

The morphologic and immunohistochemical spectrum of papillary renal cell carcinoma: study including 132 cases with pure type 1 and type 2 morphology as well as tumors with overlapping features.

Papillary renal cell carcinomas (pRCC) are classically divided into type 1 and 2 tumors. However, many cases do not fulfill all the criteria for either type. We describe the clinical, morphologic, and immunohistochemical (IHC) features of 132 pRCCs to better characterize the frequency and nature of tumors with overlapping features. Cases were reviewed and classified; IHC evaluation of CK7, EMA, TopoII&agr;, napsin A, and AMACR was performed on 95 cases. The frequencies of type 1, type 2, and “overlapping” pRCC were 25%, 28%, and 47%, respectively. The 2 categories of “overlapping” tumors were: (1) cases with bland cuboidal cells but no basophilic cytoplasm (type A); and (2) cases with predominantly type 1 histology admixed with areas showing prominent nucleoli (type B). The pathologic stage of “overlapping” cases showed concordance with type 1 tumors. Using the 2 discriminatory markers (CK7, EMA), “type A” cases were similar to type 1. Although the high–nuclear grade areas of “type B” tumors showed some staining differences from their low–nuclear grade counterpart, their IHC profile was closer to type 1. Single nucleotide polymorphism array results, although preliminary and restricted to only 9 cases (3 with overlapping features), also seemed to confirm those findings. In conclusion, we demonstrate that variations in cytoplasmic quality and/or presence of high-grade nuclei in tumors otherwise displaying features of type 1 pRCCs are similar in stage and IHC profile those with classic type 1 histology, suggesting that their spectrum might be wider than originally described.