TFE3 rearranged Renal cell carcinoma (RCC) is not very common, and demonstrates unique heterogenous morphological features overlapping other recognized entities and distinct immunoprofile. It can be ...seen in any age group, therefore practicing pathologists should be aware of the distinctive clinical settings and histologic findings associated with these tumors and subsequently employ an adequate panel of ancillary studies in order to confirm the diagnosis. Recognizing these entities remains crucial for future clinical trials and development of novel therapies.
Fumarate hydratase deficient renal cell carcinoma (FHRCC) can exhibit a heterogenous immunoprofile. In the present case, a solitary 10.5 cm mixed cystic and solid left kidney tumor showed various ...growth patterns, involving renal sinus adipose tissue and the renal pelvis. Tumor cells showed prominent nucleoli and perinucleolar halos. Aberrant diffuse (>90%), strong, and membranous carbonic anhydrase 9 and variable GATA3 expression were present. Diagnostic loss of fumarate hydratase expression and 2-succinyl cysteine overexpression (cytoplasmic and nuclear) were identified. Carbonic anhydrase 9 and GATA3 expression in FHRCC is rarely reported in the literature, and may cause misdiagnosis of clear cell RCC and/or urothelial carcinoma.
Aims. Histopathologic benign mimickers of prostate cancer have mostly focused on glandular mimics, with non-glandular mimics mainly limited to inflammatory conditions. While there is a paucity of ...literature recognizing small cystic (presumably artifactual) spaces in transurethral resection specimens, in some instances they can become florid enough to mimic vascular or epithelial neoplasms. Herein, we detailed histologic, immunophenotypic, and clinicopathologic findings in a large series of specimens showing prominent diagnostically confounding cystic spaces. Methods and Results. Sixty specimens were obtained (50 transurethral resections, 7 aquablations, 3 laser enucleations), from 17 different surgeons. Seven specimens had concurrent genitourinary pathology (4 prostatic adenocarcinoma, 1 solitary fibrous tumor, 1 prostatic atypia, 1 urothelial carcinoma in situ). The extent of cystic change among overall tissue examined ranged from 1 mm-8 mm (mean 3.4 mm), with luminal content of cystic spaces characterized as empty (72%), both empty and fluid-like (17%), and both empty and mucin-like (11%; mucin histochemical stain was negative on all specimens). Notable differences in degree of tissue cautery artifact or inflammation was not found. Immunohistochemistry performed on 30 specimens showed cystic spaces negative for S100, ERG, pankeratin, and CD45. Conclusion. Although artifactual in nature, in some instances small cystic spaces encountered in prostatic transurethral resections and more novel related procedures can become florid enough to warrant recognition as a potential diagnostic confounder of vascular or epithelial neoplasms.
The differential diagnosis for oncocytic renal tumors spans the spectrum from benign entities to more aggressive renal cell carcinomas (RCC). Recent work has characterized a provisional renal ...oncocytic neoplasm, namely the low-grade oncocytic tumor (LOT), which demonstrates overlapping morphologic features with oncocytoma and chromophobe RCC, but also has a unique immunoprofile (ie, diffusely positive for KRT7, negative for KIT) and a high rate (80% to 100%) of mTOR pathway gene alterations. Given the diagnostic overlap among oncocytic tumors, we looked for concordance between mTOR pathway mutations and LOT. Thirty low-grade renal oncocytic neoplasms underwent histologic review and immunohistochemistry for KRT7 and KIT. Tumors were classified as “determinate” (eg, LOT) for tumors with solid, nested or vaguely tubular growth and diffuse KRT7 staining and negative KIT, or “indeterminate” if the morphology and/or immunostains did not fully support a definitive LOT diagnosis. Next-generation sequencing was performed without any knowledge of the diagnoses, and identified mTOR pathway mutations in 80% (12/15) of the determinate tumors, compared with 7% (1/15) in the indeterminate group. One determinate tumor was reclassified as papillary RCC (MTOR mutation negative) and 6 indeterminate tumors were confirmed to be oncocytoma (N = 4), clear cell RCC or papillary RCC with reverse polarity, respectively. Overall, integration of morphology, immunohistochemistry, and molecular data enabled a final definitive diagnosis for 70% of tumors (21 of the total 30), with a high concordance (93%) for LOT specifically in the determinate group; the remaining 9 tumors (30%) were classified as renal oncocytic neoplasm, not otherwise specified.
Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm known to occur at various soft tissue and visceral locations. Kidney is a rarely reported site for these tumors. Most of the SFTs described ...in the kidney exhibit a classical CD34-positive patternless spindle cell histology. Focal round cell morphology is seldom reported. Herein, we describe a 48-year-old male patient with renal SFT. This tumor had pure round cell morphology with a CD34−/STAT6+ immunophenotype. Fluorescent in situ hybridization and a multiplexed sequencing assay performed on an Illumina® HiSeq 4000 platform revealed NAB2 and STAT6 gene rearrangement. Renal tumors with round cell morphology are diagnostically challenging and SFT is not often considered in the differential diagnosis of a round cell tumor of the kidney. Moreover, a CD34-negative profile can be rather confounding while diagnosing such lesions. In such scenarios, a strong nuclear STAT6 immunostaining is extremely helpful in clinching the diagnosis. SFT should always be considered in the differential diagnosis of round cell tumors of the kidney due to significant diagnostic and therapeutic implications.
In some instances, the central scar of renal oncocytoma can demonstrate entrapped cells with unusual morphology and aberrant immunoprofile creating potential diagnostic confusion. Herein, 100 renal ...oncocytomas containing scars with embedded epithelial cells were identified from 6 institutions, including nephrectomies (64% partial, 36% radical) of similar laterality (left = 51%) and sex distribution (male = 56%), with patient ages ranging from 38 to 86 years (mean = 64.3years) and tumor sizes ranging from 2 to 16 cm (mean = 5.3 cm). Immunohistochemistry was performed on all tumors for KRT7, KIT, vimentin, and CA9 with staining intensity and extensity separately analyzed. Of 4 architectural patterns of cells within the scar, 60% showed tubular pattern. Of 4 cytologies within the scar, flat/elongated (49%) and cuboidal cells (40%) predominated. Within the scar, 62% showed eosinophilic cytoplasm, with 38% showing both cleared and eosinophilic cytoplasm; notably, 79% showed higher grade nuclei than typical oncocytes. A subset of scar cells showed mucinous-like basophilic secretions (19%). Compared to background renal oncocytoma, tumor cells within the scar were more often positive for vimentin, KRT7, and CA9 and more frequently negativity for KIT. Specifically, of the notable “aberrant” immunoprofiles, 79% showed KRT7 positivity/KIT negativity/vimentin positive, 84% showed vimentin positivity/CA9 positivity, and 78% showed KIT negativity/vimentin positivity/CA9 positivity. While encountering scars within renal oncocytomas is not uncommon, what is not well appreciated is the unique morphology and immunohistochemistry of tumor cells within the scar. Comparing tumor morphology and immunoprofile of the scar to the background oncocytoma is helpful to avoid interpretative confusion.
Abstract
Background
Penile melanoma (PM) is a rare tumor, accounting for less than 2% of all penile cancers. PM can occur on the surface of the glans, foreskin, and opening of the urethra. ...Furthermore, PM primarily affects older individuals and is not associated with sun exposure. Currently, there is no specific staging system for genitourinary tract melanomas, so these tumors are typically staged using the criteria for cutaneous melanoma. Limited data in the literature suggests that PM generally has a poor clinical prognosis.
Case presentation
Here, we describe two cases of PM. The first case affected a 62-year-old male who presented with hematuria and a painful tumor in the distal urethra, leading to a suspicion of penile cancer. The second case involved a 68-year-old male who noticed a rapidly evolving dark spot on his foreskin. Histological analysis confirmed the presence of melanoma in both patients. The tumors showed a diffuse and strong PRAME-positivity and lacked
BRAF
mutation in both cases. Additionally, the second tumor harbored an activating
CKIT
mutation. An enhanced PD-L1 expression was observed in both tumors.
Conclusions
We presented two rare forms of mucosal melanoma and highlighted the entities in the differential diagnosis. Based on our experience PRAME is a helpful marker for making the diagnosis of PM, and PD-L1 can predict the success of the immunotherapy. We also emphasize the need for an organ-specific staging system for PMs.
Objectives.
Accurate diagnosis of neuroblastoma may be challenging, especially with limited or inadequate specimen and at the metastatic sites due to overlapping imaging, histopathologic, and ...immunohistochemical (immunohistochemistry IHC; infidelity among various lineage-associated transcription factors eg FLI1, transducin-like enhancer 1, etc) features. GATA3 and ISL1 have recently been described as markers of neuroblastic differentiation. This study aims at determining the diagnostic utility of GATA3 and ISL1 in differentiating neuroblastoma from other pediatric malignant small round blue cell tumors.
Methods.
We evaluated GATA3 and ISL1 expression in 74 pediatric small round blue cell tumors that included 23 NMYC-amplified neuroblastomas, 11 EWSR1-rearranged round cell sarcomas, 7 SYT::SSX1-rearranged synovial sarcomas, 5 embryonal rhabdomyosarcomas, 10 Wilms tumors (nephroblastomas), 7 lymphoblastic lymphoma, 7 medulloblastoma, and 4 desmoplastic small round cell tumor.
Results.
All 23 neuroblastomas (moderate to strong staining in >50% of the tumor cells), 5 T-lymphoblastic lymphomas (moderate to strong staining in 40%-90% of the tumor cells), and 2 desmoplastic small round cell tumors (weak to moderate staining in 20%-30% of the tumor cells) expressed GATA3, while other tumors were negative. ISL1 immunoreactivity was observed in 22 (96%) neuroblastomas (strong staining in in >50% of the tumor cells, n = 17; moderate to strong staining in 26%-50% of the tumor cells, n = 5), 3 embryonal rhabdomyosarcoma (moderate to strong staining in 30%-85% of the tumor cells), 1 synovial sarcoma (weak staining in 20% of the tumor cells), and 7 medulloblastoma (strong staining in 60%-90% of the tumor cells). Other tumors were negative. Overall, GATA3 showed 86% specificity, 100% sensitivity, and 90% accuracy for neuroblastoma, with a positive predictive value (PPV) and negative predictive value (NPV) of 77% and 100%, respectively. ISLI showed 72% specificity, 96% sensitivity, and 81% accuracy for neuroblastoma, with a PPV and NPV of 67% and 97%, respectively. After the exclusion of T-lymphoblastic lymphoma and desmoplastic small round cell tumors, GATA3 had 100% specificity, sensitivity, accuracy, and PPV and NPV for neuroblastoma. Similarly, in pediatric small round blue cell tumors, ISL1 had 100% specificity, sensitivity, accuracy, PPV, and NPV for neuroblastoma, after embryonal rhabdomyosarcoma, synovial sarcoma, and medulloblastoma were excluded.
Conclusions
GATA3 and ISL1 may be valuable in the diagnostic work-up of neuroblastoma and may reliably be used to support the neuroblastic lineage of pediatric small round blue cell tumors. Furthermore, dual positivity helps in challenging scenarios, when there is equivocal imaging, overlapping IHC features, limited specimen, and the lack of facility for a molecular work up.
Given the variable clinical course of prostate cancer and the limitations of current prognostic factors, this study was conducted to investigate the impact of a histologically overt stromal response ...(HOST-response) to prostate cancer on clinical outcomes after radical prostatectomy.
This retrospective analysis utilized The Cancer Genome Atlas (TCGA) to evaluate data from individuals with a confirmed diagnosis of prostate cancer who underwent radical prostatectomy and had available pathology slides. These slides were assessed for the presence of a HOST-response, similar to desmoplasia. The primary endpoint was progression-free survival (PFS). A multivariable competing risk regression analysis was used to assess whether a significant association existed between HOST-response and PFS, adjusting for known prostate cancer prognostic factors.
Among the 348 patients analyzed, 166 (47.70%) demonstrated a HOST-response. After a median follow-up of 37.87 months (IQR: 21.20, 65.50), the presence of a HOST-response was significantly associated with a shorter PFS (SDHR, 2.10; 95% CI, 1.26 to 3.50;
= 0.004), after adjusting for covariates.
HOST-response in prostate cancer patients treated with radical prostatectomy is significantly associated with reduced PFS, suggesting a potential benefit from adjuvant therapy and highlighting the need for further investigation in a prospective randomized clinical trial.
