Visualizing Engrafted Human Cancer and Therapy Responses in Immunodeficient Zebrafish.

Xenograft cell transplantation into immunodeficient mice has become the gold standard for assessing pre-clinical efficacy of cancer drugs, yet direct visualization of single-cell phenotypes is difficult. Here, we report an optically-clear prkdc-/-, il2rga-/- zebrafish that lacks adaptive and natural killer immune cells, can engraft a wide array of human cancers at 37°C, and permits the dynamic visualization of single engrafted cells. For example, photoconversion cell-lineage tracing identified migratory and proliferative cell states in human rhabdomyosarcoma, a pediatric cancer of muscle. Additional experiments identified the preclinical efficacy of combination olaparib PARP inhibitor and temozolomide DNA-damaging agent as an effective therapy for rhabdomyosarcoma and visualized therapeutic responses using a four-color FUCCI cell-cycle fluorescent reporter. These experiments identified that combination treatment arrested rhabdomyosarcoma cells in the G2 cell cycle prior to induction of apoptosis. Finally, patient-derived xenografts could be engrafted into our model, opening new avenues for developing personalized therapeutic approaches in the future.

Pediatric intramuscular hemangioma in the submandibular triangle and other musculoskeletal presentations: A pediatric case series.

BACKGROUND: Intramuscular hemangiomas (IMH) account for 0.8 % or less of all benign soft tissue tumors in the general population. Due to their uncommon nature, especially in the head and neck, they are often misdiagnosed and not included in the differential diagnosis. METHODS: This study describes a case series of eleven pediatric patients with a diagnosis of IMH through a retrospective review of the electronic health records and archival records in the Department of Pathology at Children's Hospital of Colorado (CHCO). RESULTS: The index case had a unique presentation in the submandibular triangle, while the remaining ten cases are appendicular and thoracolumbar in nature. CONCLUSIONS: This case series contributes to the sparse scientific literature available regarding IMH, particularly in its head and neck presentation as relevant to otolaryngologists.

Mechanisms Underlying the Rarity of Skeletal Muscle Cancers.

Skeletal muscle (SKM), despite comprising ~40% of body mass, rarely manifests cancer. This review explores the mechanisms that help to explain this rarity, including unique SKM architecture and function, which prohibits the development of new cancer as well as negates potential metastasis to SKM. SKM also presents a unique immune environment that may magnify the anti-tumorigenic effect. Moreover, the SKM microenvironment manifests characteristics such as decreased extracellular matrix stiffness and altered lactic acid, pH, and oxygen levels that may interfere with tumor development. SKM also secretes anti-tumorigenic myokines and other molecules. Collectively, these mechanisms help account for the rarity of SKM cancer.

Unique Case of Rare Non-Neural Granular Cell Tumor of the Rectus Abdominis Muscle.

Background and Objectives: Our report contributes a unique case of a non-neural GCT occurring in an unusual location, with its development during pregnancy adding to its rarity. Materials and Methods: Granular cell tumors (GCTs), also known as Abrikossoff's tumors, are rare neoplasms of Schwann cell origin with predominantly benign behavior. We present a case of a 29-year-old female with a non-neural variant of a GCT discovered incidentally during a cesarean section, situated on the posterior surface of the rectus abdominis muscle. Results: Histologically, the tumor exhibited features consistent with a benign non-neural GCT, confirmed through an immunohistochemical analysis. Despite the atypical presentation and challenging surgical removal due to prior scarring, the patient experienced no postoperative complications and showed no signs of recurrence during follow-up. Conclusions: This case highlights the importance of considering GCTs in differential diagnoses, particularly in unusual anatomical locations, and underscores the favorable prognosis associated with timely surgical intervention.

Latency-associated peptide identifies therapeutically resistant muscle-invasive bladder cancer with poor prognosis.

BACKGROUND: Latency-associated peptide (LAP) was identified as crucial immune regulator in tumor microenvironment (TME) in recent researches. In this study, we aimed to estimate the predictive value of LAP expression for clinical survival and therapeutic response in muscle-invasive bladder cancer (MIBC). METHODS: Our study encompassed 140 MIBC patients from Zhongshan Hospital (ZSHS cohort), 401 patients from The Cancer Genome Atlas (TCGA cohort) and 195 patients received PDL1 blockade from IMvigor210 trial. Survival analyses were conducted through Kaplan-Meier curve and Cox regression model. LAP expression and its association with immune contexture were evaluated in ZSHS and TCGA cohort. RESULTS: We found that high intratumoral LAP+ cells infiltration anticipated inferior survival and adjuvant chemotherapy (ACT) response, and was closely related to an immunoevasive contexture with increased M2 macrophages, neutrophils and conspicuously a cluster of highly exhausted CD8+ T cells. The combinational analysis of LAP+ cells and CD8+ T cells infiltration stratified patients into distinct risk groups with implications for therapeutic sensitivity to PDL1 blockade and refinement of molecular classification in MIBC. CONCLUSIONS: LAP expression was correlated with patients' inferior prognosis, ACT-tolerance and an immunoevasive TME with exhausted CD8+ T cell infiltration, suggesting that LAP could serve as a promising therapeutic target in MIBC. Simultaneously, our novel TME classification based on LAP+ cells and CD8+ T cells infiltration and its potential in appraising PDL1 blockade application for MIBC patients deserved further validation.

Primary seminal vesicle epithelioid smooth muscle neoplasm of uncertain biologic potential.

We present the case of a 73-year-old male patient who presented with obstructive urinary symptoms, pelvic pressure, and hematuria. CT imaging revealed a heterogenous prostate enlargement, and MRI demonstrated the mass to be arising from the seminal vesicle. Prostate biopsies showed benign tissue. Surgical excision was completed and pathology revealed it to be an epithelioid smooth muscle neoplasm of uncertain biologic potential. This is only the second known case of such a seminal vesicle tumour. As soft tissue sarcomas of the seminal vesicle emerge in the literature, we may develop a better understanding of their biologic behaviour and prognostic potential.

[Histiocyte-rich rhabdomyoblastic tumor: a clinicopathological and molecular genetic analysis].

Objective: To investigate the clinicopathologic and molecular genetic characteristics, diagnosis, differential diagnosis, treatment and prognosis of histiocyte-rich rhabdomyoblastic tumor (HRRMT). Methods: The clinical data of two cases of HRRMT diagnosed in Fujian Provincial Hospital and Fujian University of Traditional Chinese Medicine Affiliated People's Hospital from 2020 to 2021 were collected. Histopathology and immunohistochemical (IHC) staining were used to assess morphological changes; the genetic changes were analyzed with next-generation sequencing. The relevant literature was reviewed. Results: Both cases showed well-defined solid nodules and soft masses. Microscopically, the tumors had a fibrous pseudocapsule with lymphocytic aggregation, and locally invaded the surrounding skeletal muscle tissue, and the tumor cells were fusiform to epithelioid with an intensive foamy histiocytic infiltrate. No necrosis or mitosis was observed. Immunophenotyping showed the tumor cells were positive for desmin, either one or both skeletal muscle markers (myogenin or MyoD1), and negative for h-caldesmon, ALK and SMA. The Ki-67 index was<5%. Using next-generation sequencing, one case was found to harbour KRAS (G12D) and MSH3 (Q470*) mutations. Conclusions: HRRMT is a newly described skeletal muscle tumor with uncertain malignant potential. Its diagnosis and differential diagnosis depend on morphologic and IHC staining. No specific molecular genetics changes have been identified so far.

Renal function outcomes in patients with muscle-invasive bladder cancer treated with neoadjuvant pembrolizumab and radical cystectomy in the PURE-01 study.

The use of pembrolizumab has been largely accepted in several advanced types of cancers. PURE 01 study (NCT02736266) enrolled consecutively 143 patients with muscle-invasive bladder cancer who received 3 cycles of pembrolizumab 200 mg every 3 weeks before planned radical cystectomy (RC). Clinical, pathological and laboratory data were collected to investigate the relationship between renal function, immunotherapy and cancer-related outcomes. Serum creatinine and estimated glomerular filtration rate (eGFR) using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine-equation 2009 were reported at baseline and after every cycle of pembrolizumab; the T stage from clinical classification TNM (cTNM) was stated before the treatment. Our analysis did not demonstrate a significant impairment of eGFR after any cycle of pembrolizumab, neither in the overall cohort nor in subgroups considering the T stages or the CKD G-categories according to K-DIGO 2012 classification. In conclusion, in neoadjuvant setting before RC our results suggest that pembrolizumab administration is safe for renal function preservation.

New insights into antimetastatic signaling pathways of melatonin in skeletomuscular sarcoma of childhood and adolescence.

Melatonin is an indole produced by the pineal gland at night under normal light or dark conditions, and its levels, which are higher in children than in adults, begin to decrease prior to the onset of puberty and continue to decline thereafter. Apart from circadian regulatory actions, melatonin has significant apoptotic, angiogenic, oncostatic, and antiproliferative effects on various cancer cells. Particularly, the ability of melatonin to inhibit skeletomuscular sarcoma, which most commonly affects children, teenagers, and young adults, is substantial. In the past few decades, the vast majority of references have focused on the concept of epithelial-mesenchymal transition involvement in invasion and migration to allow carcinoma cells to dissociate from each other and to degrade the extracellular matrix. Recently, researchers have applied this idea to sarcoma cells of mesenchymal origin, e.g., osteosarcoma and Ewing sarcoma, with their ability to initiate the invasion-metastasis cascade. Similarly, interest of the effects of melatonin has shifted from carcinomas to sarcomas. Herein, in this state-of-the-art review, we compiled the knowledge related to the molecular mechanism of antimetastatic actions of melatonin on skeletomuscular sarcoma as in childhood and during adolescence. Utilization of melatonin as an adjuvant with chemotherapeutic drugs for synergy and fortification of the antimetastatic effects for the reinforcement of therapeutic actions are considered.

Amplification of 7p12 Is Associated with Pathologic Nonresponse to Neoadjuvant Chemotherapy in Muscle-Invasive Bladder Cancer.

Pathologic downstaging (pDS) to neoadjuvant chemotherapy (NAC) is one of the most important predictors of survival in muscle-invasive bladder cancer (MIBC). The use of NAC is limited as pDS is only achieved in 30% to 40% of cases and predictive biomarkers are still lacking. We performed a comprehensive immunomolecular biomarker analysis to characterize the role of immune cells and inhibitory checkpoints, genome-wide frequencies of copy number alterations, mutational signatures in whole exome, and tumor mutational burden in predicting NAC response. Our retrospective study included 23 primary MIBC patients who underwent NAC, followed by radical cystectomy. pDS to NAC was a significant prognostic factor for better recurrence-free survival (P < 0.001), with a median time to recurrence of 41.2 versus 5.5 months in nonresponders. DNA damage repair alterations were noticed in 38.1% (n = 8), confirming a positive correlation with high tumor mutational burden (P = 0.007). Chromosomal 7p12 amplification, including the genes HUS1, EGFR, ABCA13, and IKZF1, predicted nonresponse in patients with a sensitivity, a negative predictive value, and a specificity of 71.4%, 87.5%, and 100%, respectively. Total count of CD3+ T cells/mm2 tumor was a significant predictor of NAC response. In conclusion, 7p12 amplification may predict nonresponse to NAC and worse survival in MIBC. Multicenter, prospective trials with sufficient statistical power may further fortify these findings.

Smooth muscle hamartoma and striated muscle hamartoma: Clinicopathologic characterization of two rare entities and literature review.

Smooth muscle hamartoma (SMH) and striated muscle hamartoma (STH) are anomalous proliferations of smooth muscle or striated muscle, respectively, in anatomic sites where these tissues are normally present. To date, only limited cases have been reported describing these lesions. In this study, we sought to characterize the clinicopathologic features of both SMH and STH. A total of 27 cases of SMH and 12 cases of STH from 1990 to 2020 were identified. SMH cases had a slight male predominance (63%) and a mean age of presentation of 20 years (range: 4 months-91 years), with a mean size of 9.3 mm (±13.3). In contrast, STH were equally distributed in gender, with a mean age of presentation of 40 years (range: 3 months-66 years) and a mean size of 5.7 mm (±3.6). SMH were more commonly located in the torso and extremities (70%) and STH in the head and neck area (92%). One case of SMH recurred after 1.1 years and in the initial diagnosis the lesion was present at the tissue edge. None of the cases of STH had a recurrence. We present the largest cohort of SMH and STH, and report the first case of a recurrent SMH, suggesting the importance of obtaining a clean margin for these lesions.

Adipocyte-rich CTNNB1-mutated Intramuscular Gardner Fibroma Progressing to Desmoid Fibromatosis.

Gardner fibroma (GF) is a benign soft-tissue tumor that is associated with Gardner syndrome and can progress to, or co-occur with, desmoid fibromatosis (DF). Herein, we report a unique case of an 11-year-old boy who presented with a rapidly growing soft-tissue mass after biopsy of a stable fat-rich lesion present in the calf muscles since infancy, with Magnetic resonance imaging findings suggesting an intramuscular adipocytic tumor. The resection showed GF and DF. DF arising from a preexisting GF (the so-called "GF-DF sequence") is a well-documented phenomenon. Although immunohistochemistry was negative for nuclear ß-catenin expression, a CTTNB1 S45F mutation, which has been associated with aggressive behavior in DF, was identified in both components using a next-generation sequencing-based molecular assay. This is the first time a mutation in CTNNB1 has been identified in GF and the GF-DF sequence, thus expanding our knowledge of the molecular pathogenesis of the GF-DF sequence and highlighting the role of molecular testing in pediatric soft-tissue tumors. The histologic findings of an adipocyte-rich intramuscular GF also are unique, expanding the morphological spectrum of GF and adding GF to the differential diagnosis of intramuscular lesions with an adipocytic component.

Standard diffusion-weighted, intravoxel incoherent motion, and dynamic contrast-enhanced MRI of musculoskeletal tumours: correlations with Ki67 proliferation status.

AIM: To determine whether quantitative parameters derived from conventional diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM), and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) correlate with the Ki67 proliferation status in musculoskeletal tumours. MATERIALS AND METHODS: Twenty-eight patients with musculoskeletal tumours diagnosed via surgical specimen histological analysis who underwent standard DWI, IVIM, and DCE were reviewed retrospectively. The mean standard DWI (apparent diffusion coefficient [ADC]), IVIM (pure diffusion coefficient [D], pseudo-diffusion coefficient [D∗] and perfusion fraction [ƒ]), and DCE (volume transfer constant [Ktrans], rate constant [Kep], and extravascular extracellular volume fraction [Ve]) parameters were measured and correlated with the Ki67 index. The Ki67 value was categorised as high (>20%) or low (≤20%). RESULTS: The ADC and D values correlated negatively with the Ki67 index (r=-0.711∼-0.699, p<0.001), whereas the Ktrans and Kep values correlated positively with the Ki67 index (r=0.389-0.434, p=0.021, 0.041). The ADC and D values were lower (p<0.001), whereas the Ktrans and Kep values were higher (p=0.011, 0.005) in musculoskeletal tumours with a high Ki67 status than in those in a low status. The ADC and D demonstrated the largest area under the receiver-operating characteristic curve (AUC = 0.953), which is statistically bigger than the AUC of Ktrans and Kep (0.784 and 0.802, respectively). CONCLUSION: ADC, D, Ktrans, and Kep correlate with the Ki67 index. ADC and D are the strongest quantitative parameters for predicting Ki67 status.

Imaging features of skeletal muscle lymphoma: a case report and literature review.

BACKGROUND: Diffuse large B cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL), occurring predominantly in older people. Skeletal muscle lymphoma is a rare form of DLBCL, most frequently affecting the thigh, upper extremities, calf, and pelvis. CASE PRESENTATION: We report a case of skeletal muscle DLBCL that was diagnosed using ultrasound (US)-guided biopsy. A 70-year-old man presented with progressive swelling and pain in the left lower extremity and an elevated erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP), ferritin, and CA125 levels. US, magnetic resonance imaging (MRI), and computed tomography (CT) showed diffuse lesions in several muscles of the left lower extremity. Positron emission tomography/CT (PET/CT) showed FDG-uptake in the affected muscles. The patient was treated with chemotherapy and achieved a good response. A systematic review of the literature published between 1992 and 2019 was conducted to investigate the role of imaging, including imaging-guided biopsy, in the diagnosis of skeletal muscle lymphoma. CONCLUSIONS: Skeletal muscle lymphoma is rare. US and MRI features include enlargement of muscular structures, with preservation of the architecture of the tissue and surrounding anatomical structures. Definitive diagnosis relies on histological and immunohistological analysis of a sample obtained through imaging-guided biopsy.

Combination of oral recombinant methioninase and decitabine arrests a chemotherapy-resistant undifferentiated soft-tissue sarcoma patient-derived orthotopic xenograft mouse model.

Cancer cells are methionine (MET) and methylation addicted and are highly sensitive to MET restriction. The present study determined the efficacy of oral-recombinant methioninase (o-rMETase) and the DNA methylation inhibitor, decitabine (DAC) on restricting MET in an undifferentiated-soft tissue sarcoma (USTS) patient-derived orthotopic xenograft (PDOX) nude-mouse model. The USTS PDOX models were randomized into five treatment groups of six mice: Control; doxorubicin (DOX) alone; DAC alone; o-rMETase alone; and o-rMETase-DAC combination. Tumor size and body weight were measured during the 14 days of treatment. Tumor growth was arrested only in the o-rMETase-DAC condition. Tumors treated with the o-rMETase-DAC combination exhibited tumor necrosis with degenerative changes. This study demonstrates that the o-rMETase-DAC combination could arrest the USTS PDOX tumor suggesting clinical promise.

Slow N-acetylation as a possible contributor to bladder carcinogenesis.

Bladder cancer (BCa) is an exophytic tumor that presents as either noninvasive confined to the mucosa (NMIBC) or invading the detrusor muscle (MIBC), and was recently further subgrouped into molecular subtypes. Arylamines, major BCa environmental and occupational risk factors, are mainly metabolized by the genetically polymorphic N-acetyltransferases 1, NAT1 and NAT2. In this study, we investigated the association between N-acetyltransferases genetic polymorphism and key MIBC and NMIBC tumor biomarkers and subtypes. A cohort of 250 males with histologically confirmed urothelial BCa was identified. Tumors were genotyped for NAT1 and NAT2 using real-time polymerase chain reaction (PCR), and characterized for mutations in TP53, RB1, and FGFR3 by PCR-restriction fragment length polymorphism. Pathology data and patients' smoking status were obtained from medical records. Pearson χ2 and Fisher exact tests were used to check for associations and interactions. Results show that NAT1 G560 A polymorphism is significantly associated with higher muscle-invasiveness (MIBC vs NMIBC; P = .001), higher tumor grade (high grade vs low grade; P = .011), and higher FGFR3 mutation frequency within the MIBC subgroup (P = .042; .027). NAT2 G857 A polymorphism is also found to be significantly associated with higher muscle-invasiveness (MIBC vs NMIBC; P = .041). Our results indicate that slow N-acetylation is a contributor to bladder carcinogenesis and muscle-invasiveness. These findings highlight NAT1 as a biomarker candidate in BCa and a potential target for drug development.

Factors influencing quality of life, function, reintegration and participation after musculoskeletal tumour operations.

BACKGROUND: The number of people living with soft-tissue and bone sarcomas is increasing due to improved individual therapy and changes in demographics. At present, there are no recommendations for psychological co-treatment, occupational and social reintegration following the treatment of soft tissue and bone sarcomas. METHODS: Seventy-four patients, 42 males and 32 females, aged between 18 and 80 years (54.58 ± 16.99 yr.) with soft-tissue (62) and bone sarcomas (12) were included to answer five standardized and one personal questionnaire regarding quality of life, function, reintegration and participation after surgical treatment. RESULTS: A number of tumour-specific and patient-specific factors were identified that affected the therapeutic outcome. Patients with sarcoma of the lower extremity described poorer mobility. Patients who underwent amputation reported a higher anxious preoccupation. Patients with a higher range of education were less fatalistic and avoiding. The size of tumours or additive radiation therapy did not affect the post-therapeutic quality of life, coping and function. There was a good correlation between anxiety and depression with occupational reintegration, function, quality of life and coping. CONCLUSION: Patients with sarcomas of the lower limb have a higher demand for postoperative rehabilitation and need more help in the postoperative occupational reintegration. Furthermore patients that underwent limb-preserving operations reported better postoperative function and quality of life. Risk assessment using patient-specific factors and an intensive psychological co-treatment may have a large role in the co-treatment of patients from the beginning of their cancer therapy.

Immune checkpoint inhibition in muscle-invasive and locally advanced bladder cancer.

PURPOSE OF REVIEW: Immune-checkpoint inhibitors (CPIs) have been implemented in the treatment algorithm of metastatic urothelial cancer as they have shown higher and more sustained responses compared with conventional second-line chemotherapy. Recently, several clinical trials have reported on CPIs in earlier disease stages such as muscle-invasive bladder cancer (MIBC). This review summarizes ongoing clinical trials and results from early phase clinical trials in muscle invasive and locally advanced bladder cancer. RECENT FINDINGS: In phase II clinical trials, neoadjuvant use of CPIs as mono and combination therapy, in patients with MIBC planned for radical cystectomy, has shown promising pathological complete response rates. Whether this will translate in survival benefit remains to be assessed. Combination of CPIs and conventional chemotherapy or other targeted agents promises to increase the efficacy of perioperative systemic therapy with potentially additive toxicities. Recently, preclinical models of combined trimodal therapy with CPIs delivered the proof of principle leading to several ongoing trials in this setting. SUMMARY: First results of clinical trials evaluating CPIs in MIBC demonstrate very promising results that warrant further investigation as they could revolutionize management of MIBC in the near future. The trend and hope are toward higher rates of safe and sustained bladder preservation.

Utility of Motor and Somatosensory Evoked Potentials for Neural Thermoprotection in Ablations of Musculoskeletal Tumors.

PURPOSE: To characterize the utility of monitoring transcranial electrical motor evoked potentials (TCeMEPs) and somatosensory evoked potentials (SSEPs) for neural thermoprotection during musculoskeletal tumor ablations. MATERIALS AND METHODS: Retrospective review of 29 patients (16 male; median age, 46 y; range, 7-77 y) who underwent musculoskeletal tumor radiofrequency ablation (n = 8) or cryoablation (n = 22) with intraprocedural TCeMEP and SSEP monitoring was performed. The most common tumor histologies were osteoid osteoma (n = 6), venous malformation (n = 5), sarcoma (n = 5), renal cell carcinoma (n = 4), and non-small-cell lung cancer (n = 3). The most common tumor sites were spine (n = 22) and lower extremities (n = 4). Abnormal TCeMEP change was defined by 100-V increase above baseline threshold activation for a given myotome; abnormal SSEP change was defined by 60% reduction in baseline amplitude and/or 10% increase in latency. RESULTS: Abnormal changes in TCeMEP (n = 9; 30%) and/or SSEP (n = 5; 17%) occurred in 12 procedures (40%) and did not recover in 5 patients. Patients with unchanged TCeMEP/SSEP activities throughout the procedure (n = 18) did not have motor or sensory symptoms after the procedure; 3 (60%) with unrecovered activity changes and 2 (29%) with transient activity changes had new motor (n = 1) or sensory (n = 4) symptoms. Relative risk for neurologic sequelae for patients with unrecovered TCeMEP/SSEP changes vs those with transient or no changes was 7.50 (95% confidence interval, 1.66-33.9; P = .009). CONCLUSIONS: Abnormal activity changes of TCeMEP or SSEP during percutaneous ablative procedures correlate with postprocedural neurologic sequelae.

Molecular profiling in muscle-invasive bladder cancer: more than the sum of its parts.

Bladder cancers are biologically and clinically heterogeneous. Recent large-scale transcriptomic profiling studies focusing on life-threatening muscle-invasive cases have demonstrated a small number of molecularly distinct clusters that largely explain their heterogeneity. Similar to breast cancer, these clusters reflect intrinsic urothelial cell-type differentiation programs, including those with luminal and basal cell characteristics. Also like breast cancer, each cell-based subtype demonstrates a distinct profile with regard to its prognosis and its expression of therapeutic targets. Indeed, a number of studies suggest subtype-specific differential responses to cytotoxic chemotherapy and to therapies that inhibit a number of targets, including growth factors (EGFR, ERBB2, FGFR) and immune checkpoint (PD1, PDL1) inhibitors. Despite burgeoning evidence for important clinical implications, subtyping has yet to enter into routine clinical practice. Here we review the conceptual basis for intrinsic cell subtyping in muscle-invasive bladder cancer and discuss evidence behind proposed clinical uses for subtyping as a prognostic or predictive test. In deliberating barriers to clinical implementation, we review pitfalls associated with transcriptomic profiling and illustrate a simple immunohistochemistry (IHC)-based subtyping algorithm that may serve as a faster, less expensive alternative. Envisioned as a research tool that can easily be translated into routine pathology workflow, IHC-based profiling has the potential to more rapidly establish the utility (or lack thereof) of cell type profiling in clinical practice. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.