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TFEB is overexpressed in TFEB-rearranged renal cell carcinomas as well as in renal tumors with amplifications of TFEB at 6p21.1. As recent literature suggests that renal tumors with 6p21.1 amplification behave more aggressively than those with rearrangements of TFEB, we compared relative TFEB gene expression in these tumors. This study included 37 TFEB-altered tumors: 15 6p21.1-amplified and 22 TFEB-rearranged (including 5 cases from The Cancer Genome Atlas data set). TFEB status was verified using a combination of fluorescent in situ hybridization (n=27) or comprehensive molecular profiling (n=13) and digital droplet polymerase chain reaction was used to quantify TFEB mRNA expression in 6p21.1-amplified (n=9) and TFEB-rearranged renal tumors (n=19). These results were correlated with TFEB immunohistochemistry. TFEB-altered tumors had higher TFEB expression when normalized to B2M (mean: 168.9%, n=28), compared with non-TFEB-altered controls (mean: 7%, n=18, P=0.005). Interestingly, TFEB expression in tumors with rearrangements (mean: 224.7%, n=19) was higher compared with 6p21.1-amplified tumors (mean: 51.2%, n=9; P=0.06). Of note, classic biphasic morphology was only seen in TFEB-rearranged tumors and when present correlated with 6.8-fold higher TFEB expression (P=0.00004). Our results suggest that 6p21.1 amplified renal tumors show increased TFEB gene expression but not as much as t(6;11) renal tumors. These findings correlate with the less consistent/diffuse expression of downstream markers of TFEB activation (cathepsin K, melan A, HMB45) seen in the amplified neoplasms. This suggests that the aggressive biological behavior of 6p21.1 amplified renal tumors might be secondary to other genes at the 6p21.1 locus that are co-amplified, such as VEGFA and CCND3, or other genetic alterations.

In the eighth edition AJCC staging, all organ-confined disease is assigned pathologic stage T2, without subclassification. We investigated whether total tumor volume (TTV) and/or maximum tumor diameter (MTD) of the index lesion are useful in improving prediction of biochemical recurrence (BCR) in pT2 patients. We identified 1657 patients with digital tumor maps and quantification of TTV/MTD who had pT2 disease on radical prostatectomy (RP). Multivariable Cox regression models were used to assess whether TTV and/or MTD are independent predictors of BCR when adjusting for a base model incorporating age, preoperative prostate-specific antigen, RP grade group, and surgical margin status. If either tumor quantification added significantly, we calculated and reported the c-index. Ninety-five patients experienced BCR after RP; median follow-up for patients without BCR was 5.7 years. The c-index was 0.737 for the base model. Although there was some evidence of an association between TTV and BCR (P=0.088), this did not meet conventional levels of statistical significance and only provided a limited increase in discrimination (0.743; c-index improvement: 0.006). MTD was not associated with BCR (P>0.9). In analyses excluding patients with grade group 1 on biopsy who would be less likely to undergo RP in contemporary practice (622 patients; 59 with BCR), TTV/MTD was not a statistically significant predictor (P=0.4 and 0.8, respectively). Without evidence that tumor quantitation, in the form of either TTV or MTD of the index lesion, is useful for the prediction of BCR in pT2 prostate cancer, we cannot recommend its routine reporting.

The introduction of immune checkpoint blockade (ICB) therapy has transformed the management of advanced bladder cancer (BC). Despite its limitations, PD-L1 immunohistochemistry may serve as a predictive biomarker of anti-PD-L1/PD1 therapy. While urothelial carcinoma (UC) patients with predominant or pure variant histology (UCV) account for up to one-third of advanced cases, to date, most ICB BC studies have excluded patients with such histologies. To assess the potential utility of ICB in patients with UCV, we analyzed PD-L1 expression in UCV and compared 3 commonly used and commercially available PD-L1 antibodies. Full sections from 84 UCV cases were stained with clones SP263, 22C3, and SP142, all of which are considered predictive assays to identify UC patients who are more likely to respond to anti-PD-1/PD-L1 inhibitors durvalumab, pembrolizumab, and atezolizumab, respectively. Expression on tumor cells (TC) and tumor-infiltrating immune cells (IC) was assessed. Staining extent and characteristics were evaluated, and concordance among the 3 clones was determined at various cutoff points as used in previous studies in BC. We found that PD-L1 was expressed in a significant percentage of UCV cases at different cutoff points (cutoff 1% TC: 37% to 54%, cutoff 5% TC: 23% to 37%), with the highest expression in UC with squamous differentiation. These figures are equal to or higher than those for classic/pure UC (4% to 30%). The results suggest that patients with UCV may benefit from anti-PD-1/PD-L1 therapy and argue against the exclusion of UC with predominant or pure variant histology from clinical ICB studies. The highest expression in both TC and IC was observed with clone SP263, followed by 22C3 and SP142, and all clones showed strong agreement in a pairwise comparison, both in TC and IC (R-values: 0.780 to 0.901), which indicates that all 3 clones are potentially useful in the evaluation of PD-L1 expression in UCV.

The differential diagnosis of renal cell neoplasms with solid or nested architecture and eosinophilic cytoplasm has become increasingly complex. Despite recent advances in classifying a number of entities exhibiting this morphology, some tumors remain in the unclassified category. Here we describe a morphologically distinct group of sporadic renal cell carcinoma (RCC) with predominantly nested architecture, eosinophilic, and remarkably vacuolated cytoplasm retrospectively identified from a cohort of previously unclassified tumors. We examined the clinicopathologic and immunohistochemical features of these tumors and investigated their mutational and copy number alterations using a targeted next-generation sequencing platform. The study included 7 patients with a mean age of 54 years (range: 40 to 68 y) and a male to female ratio of 3:4. All patients presented with a solitary renal mass and had no prior medical or family history raising concern for syndromic conditions. Tumors were well-circumscribed, unencapsulated, and comprised of nests of eosinophilic cells in a hypocellular and often edematous stroma. Tumor cells had round nuclei with prominent nucleoli and granular cytoplasm with striking vacuolization. Thick-walled vessels and calcifications were also frequently present, whereas increased mitotic activity, necrosis, foamy histiocytes or lymphocytic infiltrates were not identified. All cases were positive for PAX8, had retained expression of SDHB and FH, and exhibited a CK7-/CK20- phenotype. While cathepsin-K was positive in 5 cases, none exhibited immunoreactivity to HMB45 or Melan A, or TFE3 immunostaining. Next-generation sequencing identified somatic inactivating mutations of TSC2 (3/5 tumors tested) or activating mutations of MTOR (2/5) as the primary molecular alterations, consistent with hyperactive mTOR complex 1 signaling which was further demonstrated by phospho-S6 and phospho-4E-BP1 immunostaining. Copy number analysis revealed a loss of chromosome 1 in both cases with MTOR mutation. These tumors represent a novel subset of sporadic RCC characterized by alterations in TSC1-TSC2 complex or the mTOR complex 1 pathway. Recognition of their characteristic morphologic and immunophenotypic features will allow them to be readily identified and separated from the unclassified RCC category.

From the advent of the Gleason grading system for prostate cancer, cancer displaying intraluminal necrotic cells and/or karyorrhexis within cribriform/solid architecture, a phenomenon termed "comedonecrosis," has been assigned pattern 5. Intraductal carcinoma (IDC-P) shows morphologic overlap with high-grade cribriform/solid adenocarcinoma architecturally and cytologically and may also show central necrosis, yet due to the presence of basal cells at the duct periphery is not currently assigned a grade in clinical practice. On the basis of observations from routine clinical cases, we hypothesized that comedonecrosis was more significantly associated with IDC-P than invasive disease. From a large series of mapped radical prostatectomy specimens (n=933), we identified 125 high-grade (≥Gleason score 4+3=7), high-volume tumors with available slides for review. All slides were examined for the presence of unequivocal comedonecrosis. Standard immunohistochemistry for basal cell markers was performed to detect basal cell labeling in these foci. In total, 19 of 125 (15%) cases showed some ducts with comedonecrosis-9 cases with 1 focus and 10 cases with ≥2 foci; in all, a total of 73 foci of true comedonecrosis were evaluated. Immunohistochemical stains revealed labeling for basal cell markers in a basal cell distribution for at least some comedonecrosis foci in 18 of 19 (95%) cases, 12 with IDC-P exclusively and 6 with a mix of IDC-P and invasive carcinoma comedonecrosis foci. These results suggest that comedonecrosis is strongly associated with IDC-P and hence, the routine assignment of pattern 5 to carcinoma exhibiting comedonecrosis should be reconsidered.

Mucinous tubular and spindle cell carcinoma (MTSCC) of the kidney is a rare type of renal cell carcinoma that frequently exhibits histologic and immunophenotypic features overlapping with type 1 papillary renal cell carcinoma (PRCC). To clarify molecular attributes that can be used for this difficult differential diagnosis, we sought to delineate the genome-wide copy number alterations in tumors displaying classic histologic features of MTSCC in comparison to the solid variant of type 1 PRCC and indeterminate cases with overlapping histologic features. The study included 11 histologically typical MTSCC, 9 tumors with overlapping features between MTSCC and PRCC, and 6 cases of solid variant of type 1 PRCC. DNA samples extracted from macrodissected or microdissected tumor areas were analyzed for genome-wide copy number alterations using an SNP-array platform suitable for clinical archival material. All cases in the MTSCC group exhibited multiple chromosomal losses, most frequently involving chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22, while lacking trisomy 7 or 17. In contrast, cases with overlapping morphologic features of MTSCC and PRCC predominantly showed multiple chromosomal gains, most frequently involving chromosomes 7, 16, 17, and 20, similar to the chromosomal alteration pattern that was seen in the solid variant of type 1 PRCC cases. Morphologic comparison of these molecularly characterized tumors identified histologic features that help to distinguish MTSCC from PRCC, but immunohistochemical profiles of these tumors remained overlapping, including a marker for Hippo-Yes-associated protein signaling. Characteristic patterns of genome-wide copy number alterations strongly support MTSCC and PRCC as distinct entities despite their immunohistochemical and certain morphologic overlap, and help define histologic features useful for the classification of questionable cases.

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome is an autosomal dominant disorder in which germline mutations of fumarate hydratase (FH) gene confer an increased risk of cutaneous and uterine leiomyomas and renal cancer. HLRCC-associated renal cancer is highly aggressive and frequently presents as a solitary mass. We reviewed the clinicopathologic features of 9 patients with renal tumors presenting as sporadic cases but who were later proven to have FH germline mutations. Histologically, all tumors showed mixed architectural patterns, with papillary as the dominant pattern in only 3 cases. Besides papillary, tubular, tubulopapillary, solid, and cystic elements, 6 of 9 tumors contained collecting duct carcinoma-like areas with infiltrating tubules, nests, or individual cells surrounded by desmoplastic stroma. Prominent tubulocystic carcinoma-like component and sarcomatoid differentiation were identified. Although all tumors exhibited the proposed hallmark of HLRCC (large eosinophilic nucleolus surrounded by a clear halo), this feature was often not uniformly present throughout the tumor. Prior studies have shown that a high level of fumarate accumulated in HLRCC tumor cells causes aberrant succination of cellular proteins by forming a stable chemical modification, S-(2-succino)-cysteine (2SC), which can be detected by immunohistochemistry. We thus explored the utility of detecting 2SC by immunohistochemistry in the differential diagnosis of HLRCC tumors and other high-grade renal tumors and investigated the correlation between 2SC staining and FH molecular alterations. All confirmed HLRCC tumors demonstrated diffuse and strong nuclear and cytoplasmic 2SC staining, whereas all clear cell (184/184, 100%), most high-grade unclassified (93/97, 96%), and the large majority of "type 2" papillary (35/45, 78%) renal cell carcinoma cases showed no 2SC immunoreactivity. A subset of papillary (22%) and rare unclassified (4%) tumors showed patchy or diffuse cytoplasmic staining without nuclear labeling, unlike the pattern seen with confirmed HLRCC tumors. Sequencing revealed no germline or somatic FH alterations in 14 tumors that either exhibited only cytoplasmic 2SC staining (n=5) or were negative for 2SC (n=9), despite their HLRCC-like morphologic features. Our results emphasize the pivotal role of pathologic examination in the diagnosis of HLRCC patients and indicate immunohistochemical detection of 2SC as a useful ancillary tool in the differentiation of HLRCC renal tumors from other high-grade renal cell carcinomas.

Despite multiple studies, many clinicopathologic issues about chromophobe renal cell carcinoma (RCC) remain contentious; for example, its biological behavior-whether better or similar to papillary RCC, the incidence of sarcomatoid features, and whether pathologic features such as necrosis, nuclear grade, and tumor stage predict worse outcome. We studied 203 consecutive primary chromophobe RCCs resected at our institution in an attempt to answer these and other questions. The tumors showed significant progressive decrease in size and stage (P=0.047 and 0.001) from 1980 to 2000. Five patients had metastasis at presentation, and further disease-specific events (recurrence/metastasis/death due to disease) occurred in 8 more. Only 4 of 203 tumors had sarcomatoid features. Over median follow-up of 6.1 years (range, 0.1 to 18 y), 5-year and 10-year disease-specific events occurred in 3.7% (95% CI, 1.5%, 7.4%) and 6.4% (95% CI, 2.7%, 12.2%) patients. Outcomes showed significant association with tumor size, small-vessel invasion, sarcomatoid features, and microscopic necrosis (P≤0.05 each). pT stage or nodal metastasis tended to show some association, without reaching statistical significance (P=0.05 and 0.06, respectively). A modified tumor grading scheme, somewhat similar to that proposed recently, mitotic index, cytologic eosinophilia, and architecture, were not significantly associated with outcome. In conclusion, sarcomatoid differentiation is quite uncommon in chromophobe RCC. Tumor size, small-vessel invasion, sarcomatoid differentiation, and microscopic necrosis are the only features that are significantly associated with adverse outcome. On the basis of this long follow-up on a large number of cases, chromophobes seem to have better clinical outcomes than those reported for clear cell and papillary RCCs.

Multiple therapeutic options for renal tumors that are now available have put pathologists under increasing pressure to render diagnosis on limited material. Results on biopsies by hematoxylin and eosin (H&E) have historically not been encouraging. Currently, multiple immunohistochemical markers with differential expression in these renal tumors are available. We studied the utility of such markers on needle biopsies that were obtained ex vivo. After nephrectomy, two 18-guage cores were obtained and processed routinely. Expressions of carbonic anhydrase (CA) IX, CD117, α-methylacyl-CoA racemase (AMACR), cytokeratin 7 (CK7), and CD10 were evaluated. Results, with or without immunostaining, were compared with the final nephrectomy diagnosis. We studied 145 tumors, including 119 renal cell carcinomas (83 clear cell, 18 papillary, 14 chromophobe, and 4 type unclassified), 11 oncocytomas, and 15 miscellaneous tumors. Adequate evaluable material was present in 123 (85%) cases. In such biopsies, 81% of cases were correctly classified by H&E alone, with correct diagnosis in 90% of cases in the most common tumor subtypes (clear cell, papillary and chromophobe renal cell carcinoma, and oncocytoma). By adding immunostains, the accuracy was 90% overall and 99% among the 4 most common subtypes. The following extent and patterns of immuneexpression were highly useful in the diagnoses: diffuse, membranous CAIX expression in clear cell renal cell carcinoma, diffuse positivity for AMACR in papillary renal cell carcinoma, distinct peripheral cytoplasmic accentuation for CD117 in chromophobe renal cell carcinoma, widespread and intense positivity for CK7 in chromophobe and papillary renal cell carcinoma, and diffuse membranous reactivity in clear cell and patchy/luminal in papillary renal cell carcinoma for CD10. In conclusion, utilizing immunostains improves classification of renal tumors on needle biopsy, which may be of particular help for pathologists with limited experience. Both extent and patterns must be considered for a definitive diagnosis.

Pelvic lymph node (LN) metastasis is a well-recognized route of prostate cancer spread. However, the relationship between topography and the pathologic features of primary prostatic cancers and patterns of pelvic LN metastasis has not been well studied. We reviewed original slides of radical prostatectomies and pelvic LN dissections from 125 patients with LN metastasis and recorded a total number of LN excised/laterality of positive LN, and localization, staging parameters, lymphovascular invasion, and volume of primary tumors., Ln Quantity and Distribution: 14.6 (mean) and 13 (median) LNs were resected. Seventy-six (61%), 33 (26%), and 16 (13%) cases had 1, 2, and >2 positive LNs; whereas 58, 44, and 20 cases had LN metastasis on the right, left, and bilaterally., Pathologic Features: Eighty-six percent (108 of 125) and 37% (46 of 125) of the cases showed extraprostatic extension and seminal vesicle invasion, whereas 64% cases showed lymphovascular invasion. Mean and median total tumor volumes were 6.39 and 3.92 cm, with ≥50% and ≥90% Gleason patterns 4/5 in 105 (84%) and 73 (58%) cases, respectively., Correlation With Dominant Tumor Location: Dominant lesions on radical prostatectomy were as follows: 50 right lobe, 44 left lobe, and 31 bilateral lobe tumors. Fifteen of 50 (30%) right lobe and 18 of 44 (41%) left lobe dominant tumors had LN metastasis on the contralateral side. Only 4% (5 of 125) of the cases were associated with anterior dominant tumors., Conclusion: Thirty percent to 40% of LN metastases occurred contralateral to the dominant tumor. LN metastasis is overwhelmingly associated with high-grade, high-stage, and large volume disease. LN positivity is rarely associated with anterior dominant tumors.

Background: Urachal carcinomas occur mostly in the bladder dome, comprising 22% to 35% of vesical adenocarcinomas, and are generally treated by partial cystectomy with en bloc resection of the median umbilical ligament and umbilicus. Detailed pathologic studies with clinical outcome correlation are few., Design: We reviewed histologic material and clinical data from 24 cases selected from a database of 67 dome-based tumors diagnosed and treated at our institution from 1984 to 2005. Follow-up information was available for all 24 patients., Result: The mean age at diagnosis was 52 years (range: 26 to 68 y). Fifteen patients were male and 9 were female. Location was the dome in 23 and dome and anterior wall in 1. Thirteen cases were pure adenocarcinoma, not otherwise specified, 9 were enteric type adenocarcinoma, and 2 were adenocarcinoma with focal components of lymphoepithelioma-like carcinoma and urothelial carcinoma with cytoplasmic clearing. Signet ring cell features were focally seen in 2 cases. Cystitis cystica and cystitis glandularis were seen in 4 and 2 cases, respectively. In all instances but 1, cystitis cystica/glandularis was focal and predominantly in the bladder overlying the urachal neoplasm. Urachal remnants were identified in 15 cases: the urachal epithelium was benign urothelial-type in 6 cases and showed adenomatous changes in 9. The overlying bladder urothelium was colonized by adenocarcinoma in 3 cases. In all 3, urachal remnants were identified and showed transition from benign to adenomatous epithelium. On immunohistochemistry, these tumors were positive for CK20 and variably positive for CK7 and 34BE12. The majority showed a cytoplasmic membranous staining pattern for beta-catenin, although in 1 case, focal nuclear immunoreactivity was identified. The Sheldon pathologic stage was pT1 in 0, pT2 in 2, pT3a in 8, pT3b in 11, pT3c in 1, pT4a in 1, and pT4b in 1 patient. One patient had a positive soft tissue margin. The mean follow-up period was 40 months (range: 0.3 to 157.6 mo). Seven of 24 (29%) cases recurred locally. The incidence of local recurrence was higher in patients who underwent a partial cystectomy alone (37.5%) versus those who had a more radical surgery (27%). Distant metastases occurred in 9 (37.5%) patients, 4 of whom had no prior local recurrence. Seven patients (29%) died of the disease. All cases with locally recurrent and metastatic disease belonged to stage pT3 or higher., Conclusions: Pathologic stage is an important prognostic factor in urachal carcinoma. Surface urothelial involvement by carcinoma and presence of cystitis cystica/glandularis do not necessarily exclude the diagnosis of urachal carcinoma. Immunostains do not unequivocally discriminate a urachal from a colorectal carcinoma, but diffuse positivity for 34BE12 would support, and diffuse nuclear immunoreactivity for beta-catenin would militate against, a diagnosis of urachal carcinoma. Local recurrence may be owing to seeding within the distal urothelial tract, particularly in tumors with a configuration that is polypoid and which open into the bladder cavity. The type of surgery performed may have an effect on local recurrence despite negative margins of resection.

Previous studies have proposed that the morphologic spectrum of prostatic glands of variable size with tall columnar cells displaying basally oriented nuclei and clear to pale pink cytoplasm (TZ-LOOK) is characteristic of the well to moderately differentiated component of transition zone (TZ) tumors. However, the specificity of these findings has not been well studied. In a recent report, we identified dominant peripheral zone (PZ) and TZ tumors situated anterior to the prostatic urethra. Currently, we evaluate the histopathologic features of 215 dominant tumors, including 63 TZ and 73 anterior PZ lesions and an additional cohort of 79 posterior PZ tumors, in radical prostatectomy specimens, to identify the prevalence of this morphology in tumors of different zonal origin. Each dominant tumor was assigned a TZ-LOOK extent score of 0 to 4, with 0 = no such morphology, 1 = 1% to 25%, 2 = 26% to 50%, 3 = 51% to 75%, and 4 = >75%. Overall, 121/215 (56%) tumors showed some degree of this histology, including 56 of 63 (89%) TZ tumors and 65 of 152 (43%) PZ tumors (P<0.0001). Thirty-seven of 215 (17%) lesions had scores of 3 to 4, with 31 (84%) of these being of TZ origin. However, only 31/63 (49%) TZ tumors had >50% TZ-LOOK. Among PZ tumors, 6/152 (4%) had predominant (>50%) TZ-LOOK morphology, yet 23/152 (15%) of all PZ tumors and 23/65 (35%) of PZ tumors displaying any degree of TZ-LOOK had scores of 2 to 3 (>25%; nonfocal). In tumors of both zones with predominant (scores 3 to 4; >50%) TZ-LOOK histology, darker glands of usual acinar adenocarcinoma was often seen at the periphery. Conversely, in tumors with nonpredominant TZ-LOOK (scores 1 to 2; 50% of this histology are very likely of TZ origin, but this scenario occurs in only half of TZ tumors. Importantly, the TZ-LOOK is nonfocal in up to 35% of PZ tumors exhibiting any degree of this morphology. Given this lack of specificity, caution should be exercised in assigning zone of origin based on this histologic appearance, especially in limited samples such as prostate needle biopsy.

Carbonic anhydrase IX (CAIX)-a protein maintaining intracellular and extracellular pH-reportedly also influences regulation of cell proliferation, oncogenesis, and tumor progression. Its expression is von Hippel-Lindau-hypoxia inducible factor pathway dependent. Immunohistochemical (IHC) studies show that CAIX is diffusely overexpressed in clear cell renal cell carcinoma (CRCC), making it a potentially important differential diagnostic marker. Prognostically, low CAIX expression reportedly indicates poor survival and low response to interleukin therapy in CRCC. Most IHC studies have used clone M75 as the primary antibody, which is not commercially available. We evaluated a new commercially available antibody (clone NB100-417) to assess its expression in CRCC and compared its results with M75. On a tissue microarray of CRCC, IHC staining was performed using both antibodies. The immunoreactivity was graded as 0; 1+, 1% to 25%; 2+, 26% to 50%; and 3+, >50% tumor cells immunoreactive. Ninety-one out of ninety-five (96%) cases showed similar staining grade with excellent agreement (kappa=0.65, weighted kappa=0.75). Grade 3+ expression of CAIX was observed in 89 (94%) cases each, with both antibodies. Both antibodies produced intense membrane-predominant expression, limited to tumor cells. More than 95% of the tumors with low nuclear grade, compared with 84% and 88% of tumors with high nuclear grade, showed 3+ expression using both antibodies. Thus, most CRCC show strong and diffuse expression of CAIX, and the expression is comparable using both antibodies. Therefore, similar to the clone M75, NB100-417 can be used as a diagnostic and potentially a prognostic marker in CRCC, with the advantage of its commercial availability.

Aggressive screening and prostate needle biopsy protocols have been successful in early detection of low-volume posterior tumors. Consequently, we have observed an increased incidence of anterior-predominant prostate cancers. However, the zones of origin, patterns of spread, and patterns of extraprostatic extension of this group of tumors have not been well studied. Of 1312 radical prostatectomies performed at our institution over a span of 4.5 years, 197 had predominant (largest) tumors anterior to the urethra in whole-mounted radical prostatectomy specimens. Detailed histopathologic analysis of this cohort was undertaken emphasizing the variability in anterior prostatic anatomy from apex through base to determine zone of origin and pathologic staging. Using this approach, 97/197 (49.2%) anterior-predominant tumors (ATs) were assigned to the anterior peripheral zone (APZ), 70 (35.5%) to the transition zone (TZ), 16 (8.1%) were of indeterminate zone, and 14 (7.1%) were of both zones. Comparing APZ and TZ tumors, there were no significant differences in Gleason scores, incidence of extraprostatic extension, overall surgical margin positivity rate, or laterality. Involvement of the anterior fibromuscular stroma was significantly more likely in tumors of TZ origin (P< or =0.01), yet was observed in 50.5% of APZ tumors. Conversely, APZ tumors were more commonly localized within the apical one third of the prostate. Most of the prostates (91.4%) also showed additional PZ tumors, which were occasionally stage determining (7/197; 3.9%). In conclusion, ATs of APZ origin are more prevalent than those arising from the TZ. Contrary to previous reports comparing TZ tumors to all PZ tumors, ATs of both zones exhibit similar grading and staging parameters in this series. Given these similarities, long-term clinical outcomes and future molecular analyses will be necessary to assess whether true differences in biology and behavior exist between tumors of TZ and APZ origin.

Juvenile xanthogranuloma (JXG) is a benign histiocytic disorder of infants and childhood. Approximately 15% of cases occur in adults. Adult JXG characteristically affect patients in their 20s and 30s; however, about 5% of patients are older than 60 years. Adult JXGs rarely regress spontaneously, and reports of concomitant extracutaneous lesions are rare. Herein, we report an exceptional case of adult xanthogranuloma in a 74-year-old woman who presented with ipsilateral breast masses and also found to have prior cutaneous lesions. This is the first reported case of cutaneous and extracutaneous adult JXG where the latter manifested in the breast as a spindle cell xanthogranuloma. Histologically, the lesion was composed predominantly of spindle cells with associated multinucleated giant cells and a chronic inflammatory cell infiltrate. Spindle cells were immunoreactive for various histiocytic markers and negative for cytokeratins, S-100, CD34, factor XIIIa, and CD1a. In the breast, the morphologic features of JXG evoked several entities in the differential diagnosis, including spindle cell metaplastic carcinoma, inflammatory pseudotumor, fibromatosis, myofibroblastoma, and phyllodes tumor. With the aid of immunohistochemical stains and appropriate clinical history, the correct diagnosis of extracutaneous adult JXG manifesting as a spindle cell xanthogranuloma can be made.