Mehra, Rohit

AimsCompared to lymphovascular invasion (LVI), hilar soft tissue invasion (HSTI) is a relatively novel pT2 staging parameter in testicular germ cell tumours (GCT), associated with metastasis at the time of diagnosis and a risk factor for disease relapse. Given diagnostic variability in how pathologists interpret HSTI, herein we explore interobserver reproducibility among genitourinary (GU) pathologists.MethodsTwenty haematoxylin and eosin‐stained digitized slides from testicular GCTs were distributed to 30 GU pathologists to classify each as HSTI or not HSTI based on their respective clinical practices; slides with concomitant LVI were excluded. Slides were then evaluated for the following morphologic features: tumour invasion beyond prominent hilar vessels, tumour invasion beyond the rete, tumour invasion beyond the level parallel to hilar adipose tissue and tumour within (directly touching) hilar adipose tissue. Interobserver reproducibility was assessed, and the morphological features were correlated with HSTI. Relationships between pathologists' interpretations, morphological features and HSTI were evaluated using hierarchical clustering.ResultsAlthough the diagnosis of HSTI was relatively uniform with a majority agreement (>67%) reached in 17/20 slides, overall interobserver reproducibility was only moderate (kappa = 0.50). Morphological features such as invasion beyond the level parallel to hilar adipose tissue and invasion into fat were more sensitive and specific for HSTI, while features such as invasion beyond hilar vessels and invasion beyond rete were less useful.ConclusionsThese findings suggest that more specific defined diagnostic criteria for testicular GCT HSTI are needed.

Introduction. Chromophobe renal cell carcinoma (chromophobe RCC) is the third major subcategory of renal tumors after clear cell RCC and papillary RCC, accounting for approximately 5% of all RCC subtypes. Other oncocytic neoplasms seen commonly in surgical pathology practice include the eosinophilic variant of chromophobe RCC, renal oncocytoma, and low-grade oncocytic unclassified RCC. Methods. In our recent next-generation sequencing based study, we nominated a lineage-specific novel biomarker LINC01187 (long intergenic non-protein coding RNA 1187) which was found to be enriched in chromophobe RCC. Like KIT (cluster of differentiation 117; CD117), a clinically utilized chromophobe RCC related biomarker, LINC01187 is expressed in intercalated cells of the nephron. In this follow-up study, we performed KIT immunohistochemistry and LINC01187 RNA in situ hybridization (RNA-ISH) on a cohort of chromophobe RCC and other renal neoplasms, characterized the expression patterns, and quantified the expression signals of the two biomarkers in both primary and metastatic settings. Results. LINC01187, in comparison to KIT, exhibits stronger and more uniform expression within tumors while maintaining temporal and spatial consistency. LINC01187 also is devoid of intra-tumoral heterogeneous expression pattern, a phenomenon commonly noted with KIT. Conclusions. LINC01187 expression can augment the currently utilized KIT assay and help facilitate easy microscopic analyses in routine surgical pathology practice.