Renal mass biopsy - a practical and clinicopathologically relevant approach to diagnosis

Advancements in imaging modalities have increased the frequency of renal mass discovery. Imaging has typically been considered sufficient to guide management for a large proportion of these tumours, but renal mass biopsies (RMBs) have an increasing role in determining malignancy and can be a valuable tool for preventing unnecessary surgery in patients with benign tumours. A structured approach should be used to help to navigate the expanding repertoire of renal tumours, many of which are molecularly defined. In terms of tumour subtyping, the pathologist's strategy should focus on stratifying patients into clinically different prognostic groups according to our current knowledge of tumour behaviour, including benign, low-grade or indolent, intermediate malignant or highly aggressive. Crucial pathological features and morphological mimicry of tumours can alter the tumour's prognostic group. Thus, pathologists and urologists can use RMB to select patients with tumours at a reduced risk of progression, which can be safely managed with active surveillance within a tailored imaging schedule, versus tumours for which ablation or surgical intervention is indicated. RMB is also crucial in the oncological setting to distinguish between different high-grade tumours and guide tailored management strategies.

Papillary renal cell carcinoma with extensive spindle cell foci: mimicker of mucinous tubular and spindle cell carcinoma

Papillary renal cell carcinoma (PRCC) is the second most common renal cell carcinoma (RCC), accounting for 10-15% of cases. Mucinous tubular and spindle cell carcinoma (MTSCC), on the other hand, accounts for only 1% of renal tumors and has a more favorable prognosis compared to PRCC. We report a 75-year-old female with a left upper pole solid renal mass displaying features of both papillary renal cell carcinoma (PRCC) and mucinous tubular and spindle cell carcinoma (MTSC). In this case, a shaggy luminal surface, multiple papillations, and psammoma bodies, absence of E-cadherin expression, and strong CD10 expression favored PRCC. Both immunohistochemistry and genomic analysis are critical to diagnose and differentiate tumors that may have overlapping features accurately.

Indolent mucinous tubular and spindle cell carcinoma of the kidney: A case report and review of the literature

Mucinous tubular and spindle cell carcinoma of the kidney (MTSCC) is a rare subtype of renal cancer. It consists of tubules separated by mucus stroma and a spindle cell. Few cases have been reported; thus, the imaging features of MTSCC are not well characterized. An MTSCC in the left kidney of a 65-year-old woman was incidentally discovered during a medical checkup. A review of the patient's medical history revealed that this kidney lump had an indolent growth process. The current study presented this case and reviewed the pathological features, imaging findings and treatment options of MTSCC to strengthen the recognition of this rare renal neoplasm by radiologists.

Inter- and intratumoral proteomics and glycosaminoglycan characterization of ALK rearranged lung adenocarcinoma tissues: a pilot study

Lung cancer is one of the most common types of cancer with limited therapeutic options, therefore a detailed understanding of the underlying molecular changes is of utmost importance. In this pilot study, we investigated the proteomic and glycosaminoglycan (GAG) profile of ALK rearranged lung tumor tissue regions based on the morphological classification, mucin and stromal content. Principal component analysis and hierarchical clustering revealed that both the proteomic and GAG-omic profiles are highly dependent on mucin content and to a lesser extent on morphology. We found that differentially expressed proteins between morphologically different tumor types are primarily involved in the regulation of protein synthesis, whereas those between adjacent normal and different tumor regions take part in several other biological processes (e.g. extracellular matrix organization, oxidation-reduction processes, protein folding) as well. The total amount and the sulfation profile of heparan sulfate and chondroitin sulfate showed small differences based on morphology and larger differences based on mucin content of the tumor, while an increase was observed in both the total amount and the average rate of sulfation in tumors compared to adjacent normal regions.

ALK rearrangement-associated renal cell carcinoma morphologically mimicking mucinous tubular and spindle cell carcinoma: a case report

BACKGROUND

Anaplastic lymphoma kinase rearrangement-associated renal cell carcinoma (ALK-RCC) is an extremely rare tumor and ALK-RCC that mimics mucinous tubular and spindle cell carcinoma (MTSCC) has been very reported only in one instance.

CASE PRESENTATION

A 42-year-old Japanese woman was admitted to our hospital for the treatment of a left renal tumor measuring 5 cm in maximum dimension. She underwent a laparoscopic left nephrectomy. Histologically, the tumor formed tubular or focally papillary structures with a small amount of spindle-shaped tumor cells against the background of prominent extracellular mucin. Although the tumor cells were negative for immunohistochemistry (IHC) of alpha-methylacyl-CoA racemase (AMACR) and lymph node metastasis was presented (these are atypical findings for MTSCC), we initially diagnosed the tumor as MTSCC based on its morphological characteristics with mucin deposition. However, an additional IHC analysis revealed that the tumor cells were diffusely positive for ALK-IHC. In addition, TPM3 exon 8 - ALK exon 20 fusion gene was detected by RNA sequencing. The tumor was thus correctly diagnosed as ALK rearrangement-associated renal cell carcinoma (ALK-RCC).

CONCLUSIONS

Since the use of molecular targeted therapy with an ALK inhibitor for ALK-RCC is promising, the correct pathological diagnosis of ALK-RCC is quite important. We strongly recommend that ALK-IHC be routinely performed for renal tumors with negative AMACR staining that mimic MTSCC.

Mucinous tubular and spindle cell carcinomas of the kidney (MTSCC-Ks): CT and MR imaging characteristics

PURPOSE

To strengthen the recognition of mucinous tubular and spindle cell carcinomas of the kidney (MTSCC-Ks) by analyzing CT and MR imaging findings of MTSCC-Ks.

MATERIALS AND METHODS

This study retrospectively enrolled ten patients with pathologically confirmed MTSCC-Ks from 2007 to 2020. The main observed imaging characteristics included growth pattern, signal characteristics on T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI), hemorrhage, necrosis, cystic degeneration, lipid component, pseudocapsule and the enhancement pattern. Apparent diffusion coefficient (ADC) value of MTSCC-Ks and normal renal cortex were measured, respectively. All imaging features were evaluated in consensus by two genitourinary radiologists.

RESULTS

All patients (53.1 ± 6.5 years, male to female, 3:7) presented with a solitary renal tumor with the mean diameter of 3.5 ± 0.4 cm. All lesions showed iso- or slight hypoattenuation on non-contrast CT with no hemorrhage but cystic degeneration (10%) and necrosis (10%). On T2WI, all lesions showed predominantly slight hypointensity with focal hyperintensity. The ADC value of MTSCC-Ks was 0.845 ± 0.017 × 10^-3 mm²/s, and ADC_tumor-to-ADC_{renal cortex} value was 0.376 ± 0.084. Pseudocapsules existed in all MTSCC-Ks on MRI. There were seven lesions showed heterogeneous enhancement, while three lesions showed homogeneous enhancement. Among them, six MTSCC-Ks showed slight multiple patchy enhancement (60%) in the corticomedullary phase, while the remaining MTSCC-Ks showed homogeneously slight enhancement (30%) or slightly stratified enhancement (10%). All MTSCC-Ks exhibited slow and progressive enhancement in the late phases.

CONCLUSION

Iso- or slight hypoattenuation on CT, slight hypointensity with focal hyperintensity on T2WI, marked diffusion restriction on DWI and ADC map, slight multiple patchy enhancement in the corticomedullary phase, and slow and progressive enhancement in the late phases are the imaging features of MTSCC-Ks, which may facilitate the diagnosis of MTSCC-Ks.

OUP accepted manuscript

Mucinous tubule and spindle cell carcinoma (MTSCC) of the kidney is a rare renal pleomorphic tumor considered as low-grade malignant, with occurring mainly in female. Few mucin-poor MTSCC cases have been reported so far. A typical MTSCC is composed of closely arranged tubules with pale mucus matrix and spindle cell components. Mucin-poor MTSCC is difficult to distinguish from other renal cell carcinomas due to small amount of mucus. We reported a case of mucin-poor MTSCC in a 37-year-old male with detailed imaging, histology, immunohistochemical and next-generation sequencing information, looking forward to providing an insight into mucin-poor MTSCC.

Comparative study of CT and MRI appearances in mucinous tubular and spindle cell carcinoma and papillary renal cell carcinoma

OBJECTIVE

To explore the feasibility of CT and MRI in differentiating mucinous tubular and spindle cell carcinoma (MTSCC) and papillary renal cell carcinoma (PRCC).

METHODS

23 patients with MTSCC and 38 patients with PRCC were studied retrospectively. CT and MRI were undertaken to investigate differences in tumour characteristics.

RESULTS

23 patients with MTSCC and 38 patients with PRCC (included 15 cases Type 1,and 23 cases Type 2), tumours (mean diameter 3.7 ± 1.6 cm vs 4.6 ± 1.7 cm, p < 0.05), cystic components (5 vs 32, p < 0.01), calcifications (3 vs 11, p > 0.05), haemorrhage (1 vs 22, p < 0.01), tumour boundaries (1 vs 37, p < 0.01), and homogeneous enhancement (20 vs 11, p < 0.01). The density of MTSCC was lower than that of PRCC, normal renal cortex (p < 0.05), except for the medulla(p > 0.05). MTSCC and PRCC tumour enhancement were lower than that for normal cortex and medulla during all enhanced phases (p < 0.05). Enhancement was higher with PRCC than with MTSCC tumours during all phases (p < 0.05). On MRI, nine cases of MTSCC and 19 cases of PRCC, tumour showed homogeneous (9 vs 3, p < 0.01), heterogeneous (0 vs 16, p < 0.01), hyperintense on T1WI (0 vs 15, p < 0.01), slightly hyperintense on T2WI (9 vs 1, p < 0.01), hypointense on T2WI (0 vs 15, p < 0.05) , relatively high signal intensity was seen on DWI (9 vs 15, p > 0.05), respectively.

CONCLUSION

CT imaging features of MTSCC include isodense or hypodense mass on unenhanced CT, with unclear boundaries; however, PRCC showed mild hyperdensity, easily have cystic components. The degree enhancement of MTSCC is lower than that for PRCC. On MR, MTSCC was slightly hyperintense on T2WI, whereas PRCC was hypointense.

ADVANCES IN KNOWLEDGE

1.CT imaging features of MTSCC include isodense or hypodense mass on unenhanced CT, with unclear boundaries.2. CT imaging features of PRCC include mild hyperdensity on unenhanced CT, easily have cystic components.3. On enhanced CT, the degree enhancement of MTSCC is lower than that for PRCC. On MR, MTSCC was slightly hyperintense on T2WI whereas PRCC was heterogeneously hypointense on T2WI.

Key Renal Neoplasms With a Female Predominance

Renal neoplasms largely favor male patients; however, there is a growing list of tumors that are more frequently diagnosed in females. These tumors include metanephric adenoma, mixed epithelial and stromal tumor, juxtaglomerular cell tumor, mucinous tubular and spindle cell carcinoma, Xp11.2 (TFE3) translocation-associated renal cell carcinoma, and tuberous sclerosis complex (somatic or germline) associated renal neoplasms. The latter category is a heterogenous group with entities still being delineated. Eosinophilic solid and cystic renal cell carcinoma is the best-described entity, whereas, eosinophilic vacuolated tumor is a proposed entity, and the remaining tumors are currently grouped together under the umbrella of tuberous sclerosis complex/mammalian target of rapamycin-related renal neoplasms. The entities described in this review are often diagnostic considerations when evaluating renal mass tissue on biopsy or resection. For example, Xp11.2 translocation renal cell carcinoma is in the differential when a tumor has clear cell cytology and papillary architecture and occurs in a young or middle-aged patient. In contrast, tuberous sclerosis complex-related neoplasms often enter the differential for tumors with eosinophilic cytology. This review provides an overview of the clinical, gross, microscopic, immunohistochemical, genetic, and molecular alterations in key renal neoplasms occurring more commonly in females; differential diagnoses are also discussed regardless of sex predilection.

Dual-Phase 99mTc-MIBI SPECT/CT in the Characterization of Enhancing Solid Renal Tumors: A Single-Institution Study of 147 Cases

PURPOSE

The aim of this study was to investigate the value of dual-phase Tc-MIBI SPECT/CT in the differential diagnosis between benign and malignant enhancing solid renal tumors.

PATIENTS AND METHODS

Totally, 180 patients were imaged with dual-phase Tc-MIBI SPECT/CT, which was performed 30 minutes and 90 minutes after Tc-MIBI administration. Among them, 147 patients with 148 histologically proved solid renal tumors met the selection criteria and were included for the final analysis. Relative quantification was performed by measuring the radioactive uptake ratio of tumor to the normal renal parenchymal background for both early and delayed images.

RESULTS

Benign renal tumors (4 renal oncocytomas and 8 lipid-poor angiomyolipomas) demonstrated a significantly higher early relative uptake value (ERUV) and delayed relative uptake value (DRUV) than malignant renal tumors (n = 136; both P < 0.0001). The ERUV cutoff value of 0.53 helped to differentiate benign from malignant renal tumors, with sensitivity of 100%, specificity of 94.8%, and accuracy of 95.3% for the diagnosis of benign renal tumors. The DRUV cutoff value of 0.50 helped to differentiate benign from malignant renal tumors, with sensitivity of 100%, specificity of 96.3%, and accuracy of 96.6% for the diagnosis of benign renal tumors. There was no statistically significant difference between the efficacy of ERUV and DRUV in the differential diagnosis between benign and malignant renal tumors (P = 0.5). The efficacies of ERUV and DRUV were all significantly higher than the retention index (both P < 0.0001).

CONCLUSIONS

Both early and delayed phase Tc-MIBI SPECT/CT are helpful for distinguishing benign renal oncocytoma and lipid-poor angiomyolipoma from malignant renal tumors, and the delayed phase imaging tends to show higher diagnostic accuracy.